title: Macy Gray

text: She then met writer-producer Joe Solo while working as a cashier in Beverly Hills. Together, they wrote a collection of songs and recorded them in Solo's studio. The demo tape gave Gray the opportunity to sing at jazz cafés in Los Angeles. Although Gray did not consider her unusual voice desirable for singing, Atlantic Records signed her. She began recording her debut record but was dropped from the label upon the departure of A&R man Tom Carolan, who had signed her to the label. Macy returned to Ohio but in 1997 Los Angeles based Zomba Label Group Senior VP A&R man Jeff Blue, convinced her to return to music and signed her to a development deal, recording new songs based on her life experiences, with a new sound, and began shopping her to record labels. In 1998, she landed a record deal with Epic Records. She performed on "Love Won't Wait", a song on the Black Eyed Peas' debut album "Behind the Front".


title: Macy Gray

text: Gray worked on her debut album in 1999 with producer Darryl Swann. Released in the summer of 1999, "On How Life Is" became a worldwide smash. The first single, "Do Something", stalled on the charts, but the second single, "I Try", made the album a success. "I Try" (which was originally featured in "Love Jones" and the Jennifer Aniston-starring romantic-comedy "Picture Perfect" in 1997) was one of the biggest singles of 1999, and subsequent singles ("Still" and "Why Didn't You Call Me") ensured the album became triple platinum in the US and quadruple platinum in the UK.


title: Macy Gray

text: In 2001, Gray won the Grammy Award for Best Female Pop Vocal Performance for "I Try", which was also nominated for "song of the year" and "record of the year". She then collaborated with Fatboy Slim, the Black Eyed Peas, and Slick Rick (on the song "The World Is Yours", from the "Rush Hour 2" soundtrack), as well as acting for the first time, in the thriller "Training Day". In August 2001, Gray was booed at the Pro Football Hall of Fame exhibition game after forgetting the lyrics to the American national anthem.


title: Macy Gray

text: Gray's "The Id" featured appearances by John Frusciante and Erykah Badu on the single "Sweet Baby" (which was co-written with longtime collaborator Joe Solo). The album peaked at number eleven on the "Billboard" 200. It fared even better in the UK, where it reached number one on the UK Albums Chart and was certified gold by the BPI.


title: Macy Gray

text: In 2002, she appeared in "Spider-Man" and contributed a remix of her song "My Nutmeg Phantasy" to its accompanying soundtrack. Gray also worked with Santana on the track "Amoré (Sexo)", for his album "Shaman".


title: Macy Gray

text: Also in 2002, she appeared on the Red Hot Organization's compilation CD in tribute to Nigerian Afropop pioneer Fela Kuti, "Red Hot and Riot". She appeared on a remake of Kuti's classic track "Water No Get Enemy" alongside prominent neo soul, hip hop and R&B artists, D'Angelo, the Soultronics, Nile Rodgers, Roy Hargrove, and Kuti's son, Femi Kuti.


title: Macy Gray

text: She recorded a duet with Zucchero called "Like the Sun (From Out of Nowhere)", which featured Jeff Beck on guitar released in 2004 on "Zu & Co.", a duet collection. Her song "Time of My Life" was included in the soundtrack to "8 Mile". A cartoon based on Gray's childhood was being developed, but it never came to fruition.


title: Macy Gray

text: In 2003, Gray released her third studio album, "The Trouble with Being Myself", to rave reviews. The lead single, "When I See You", became a radio hit in the US and a top-forty hit in the UK, although the album was not as well received by fans. Nevertheless, it became Gray's third top twenty album in the UK. A greatest hits collection and a live album were subsequently released: "The Very Best of Macy Gray" (2004) and "Live in Las Vegas" (2005). Additionally, Gray was featured on Marcus Miller's 2005 album "Silver Rain", on a cover of Prince's 1986 song "Girls & Boys". She also appeared on the soundtrack to the film "Chicago" with Queen Latifah and Lil' Kim on "Cell Block Tango/He Had it Comin'".


title: Macy Gray

text: Gray began 2007 by being kicked off-stage at a concert in Barbados for profanity (which was part of the show), but she was not aware that it was against the law in that country. She gave a public apology that night to avoid arrest.


title: Macy Gray

text: In March, Gray released her fourth studio album (sixth overall), "Big". Two singles, "Finally Made Me Happy" and "Shoo Be Doo", were released from the album. "What I Gotta Do", another track from the album, is featured on the "Shrek the Third" soundtrack. It has been considered Gray's comeback album, after a four-year hiatus since her last studio album. The album was critically acclaimed and seen by some as her best work to date. It features collaborations with Natalie Cole, Fergie, Justin Timberlake, and will.i.am, who co-executive produced the album with Gray. It was moderately successful in the US, where it debuted and peaked at number 39 on the "Billboard" 200, becoming Gray's highest-charting album since "The Id". "Big" reached number 62 on the albums chart in the UK, her lowest-charting UK album, but it achieved some success in several other countries, including Switzerland, the Czech Republic, and Finland, reaching the Top 40 on their album charts.


title: Macy Gray

text: On July 7, 2007, Gray performed at the Brazilian leg of Live Earth at Copacabana Beach in Rio de Janeiro, Brazil. Gray and her band members wore clothes bearing political messages. Gray's dress carried the message "Darfur Red Alert".


title: Macy Gray

text: In 2008, Gray launched a new campaign under the name "Nemesis Jaxson", with the single "Slap a Bitch".


title: Macy Gray

text: Early in 2009, Gray recorded the song "Don't Forget Me" for the soundtrack of "Confessions of a Shopaholic".


title: Macy Gray

text: The first single from Gray's fifth studio album "The Sellout", "Beauty in the World", is featured in the final sequence of the series finale, "Hello Goodbye", of the ABC television series, "Ugly Betty". "Beauty in the World" was also used as the theme in multiple videos created by Microsoft to promote Internet Explorer 9. Both singles released from the album ("Beauty in the World" and "Lately") were top 10 hits on the US "Billboard" Hot Dance Club Songs Chart.


title: Macy Gray

text: Upon its release, "The Sellout" received generally mixed reviews from most music critics. Metacritic gave it an average score of 57, based on 15 reviews; Andy Gill of "The Independent" gave it three out of five stars; while AllMusic writer John Bush shared a similar sentiment and panned Gray's songwriting.


title: Macy Gray

text: However, "The Boston Globe"s James Reed commended its production, and Jeremy Allen of "NME" gave the album a 7/10 rating.


title: Macy Gray

text: In 2011, Gray signed a deal with 429 Records and started recording a series of covers for her next studio album "Covered". The album was officially released on March 26, 2012. The album's first single was "Here Comes the Rain Again" (originally performed by Eurythmics). On February 16, 2012, Gray participated in the Sanremo Festival as a guest, performing alongside Gigi D'Alessio and Loredana Bertè.


title: Macy Gray

text: For the 40th anniversary of the 1972 Stevie Wonder album "Talking Book", Gray covered the entire record and released her "Talking Book" as a tribute.


title: Macy Gray

text: In an interview with Oprah Winfrey's "Where Are They Now", Gray opened up about her problems with drug abuse, stating that she was ill-prepared for the level of fame she received. The interview coincided with the release of her album "The Way", released in October 2014 on Kobalt Records. A world tour was announced shortly after its release.


title: Macy Gray

text: In 2016, Gray's career continued with an album produced by Chesky Records, the record label founded by Grammy-nominated composer and musician David Chesky. "Stripped" was released September 9, 2016, and garnered unanimous praise from critics. The album debuted at No. 3 on the Billboard Jazz Chart. Earlier that year, she was featured on Ariana Grande's song "Leave Me Lonely" from her third studio album, "Dangerous Woman".


title: Macy Gray

text: In 2001, she was the voice for Seeiah Owens in the video game "SSX Tricky". Gray sang the theme song for the Nickelodeon animated series "As Told by Ginger", composed by Jared Faber and Emily Kapnek. Gray also performed the song on the short-lived UPN romantic comedy "Second Time Around" starring Boris Kodjoe and Nicole Ari Parker in 2004. In 2006 Gray appeared in the eighth season of Bravo's "Celebrity Poker Showdown", playing for Habitat for Humanity. She finished in third place.


title: Macy Gray

text: In August 2008, Gray headlined at the 2008 Summer Sundae music festival in Leicester, England, performing cover versions of Rod Stewart's "Do Ya Think I'm Sexy?", Deee-Lite's "Groove Is in the Heart" and Radiohead's "Creep". For the gig, her band wore pink Andy Warhol wigs. On September 28, 2008, Gray sang the American national anthem as part of the Israeli flag-raising ceremony at the Israeli consulate of Los Angeles. Also in 2008, Gray collaborated with Australian DJ and singer Kaz James on the song "Can't Hold Back". The single was released in early 2009 in Australia and is credited to Kaz James featuring Macy Gray.In 2009, Gray briefly competed in season 9 of "Dancing with the Stars" with professional partner Jonathan Roberts. They were eliminated in a double elimination in week one. In 2012, she performed the Michael Jackson song "Rock with You" for a special performance of the West End musical "Thriller – Live" for BBC Children in Need Pop Goes the Musical.


title: Macy Gray

text: In 2015, Gray was featured on the song "Into the Deep" by Galactic. In 2016, Gray was featured on the song "Leave Me Lonely" by Ariana Grande. In 2018, Gray was featured alongside Dolly Parton on a re-recording of "Two Doors Down" for the "Dumplin"' soundtrack. In 2020, Gray was featured on the single "Out Of Love" by Canadian band Busty and the Bass. The band also released a notable cover of Gray's "I Try" in 2016.


title: Macy Gray

text: In 2021, Gray competed in season three of the Australian version of "The Masked Singer" as "Atlantis". On February 20, 2022, Gray performed The Star-Spangled Banner at the 2022 NBA All-Star Game. Gray represented her home state of Ohio at the 2022 America Song Contest with the song "Every Night".


title: Macy Gray

text: Gray was married to Tracy Hinds, a mortgage broker, for about two years, but they divorced prior to her rise to prominence. They have three children: Aanisah, Mel, and Happy.


title: Macy Gray

text: In a July 2022 interview on "Piers Morgan Uncensored", Gray was asked how she would define a woman, to which she answered "boobs and a vagina". She went on to state that she did not support the inclusion of transgender women in women's sports. In the days following the interview, she said that her words had been misunderstood, along with rejecting criticism she had received online for her views. In a subsequent appearance on the "Today" television show, she stated that "being a woman is a vibe".


title: Macy Gray

text: In a opinion piece published in MarketWatch in June 2021, Gray called for a redesign of the United States flag stating that it "no longer represents democracy and freedom". Her suggestions included two additional stars for Washington, D.C. and Puerto Rico, the white stripes to be recolored off-white and the stars to be given a variety of colors.


title: Macy Gray

text: Gray won five of seventeen nominations, including Grammy Awards, MTV Video Music Awards and Brit Awards.


title: Skeletal muscle

text: Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscle tissue, and are often known as muscle fibers. The muscle tissue of a skeletal muscle is striated – having a striped appearance due to the arrangement of the sarcomeres.


title: Skeletal muscle

text: Skeletal muscles are voluntary muscles under the control of the somatic nervous system. The other types of muscle are cardiac muscle which is also striated and smooth muscle which is non-striated; both of these types of muscle tissue are classified as involuntary, or, under the control of the autonomic nervous system.


title: Skeletal muscle

text: A skeletal muscle contains multiple fascicles – bundles of muscle fibers. Each individual fiber, and each muscle is surrounded by a type of connective tissue layer of fascia. Muscle fibers are formed from the fusion of developmental myoblasts in a process known as myogenesis resulting in long multinucleated cells. In these cells the nuclei termed "myonuclei" are located along the inside of the cell membrane. Muscle fibers also have multiple mitochondria to meet energy needs.


title: Skeletal muscle

text: Muscle fibers are in turn composed of myofibrils. The myofibrils are composed of actin and myosin filaments called myofilaments, repeated in units called sarcomeres, which are the basic functional, contractile units of the muscle fiber necessary for muscle contraction. Muscles are predominantly powered by the oxidation of fats and carbohydrates, but anaerobic chemical reactions are also used, particularly by fast twitch fibers. These chemical reactions produce adenosine triphosphate (ATP) molecules that are used to power the movement of the myosin heads.


title: Skeletal muscle

text: There are more than 600 skeletal muscles in the human body, making up around 40% to 50% of body weight. Most muscles occur in bilaterally-placed pairs to serve both sides of the body. Muscles are often classed as groups of muscles that work together to carry out an action. In the torso there are several major muscle groups including the pectoral, and abdominal muscles; intrinsic and extrinsic muscles are subdivisions of muscle groups in the hand, foot, tongue, and extraocular muscles of the eye. Muscles are also grouped into compartments including four groups in the arm,


title: Skeletal muscle

text: Apart from the contractile part of a muscle consisting of its fibers, a muscle contains a non-contractile part of dense fibrous connective tissue that makes up the tendon at each end. The tendons attach the muscles to bones to give skeletal movement. The length of a muscle includes the tendons. Connective tissue is present in all muscles as deep fascia. Deep fascia specialises within muscles to enclose each muscle fiber as endomysium; each muscle fascicle as perimysium, and each individual muscle as epimysium. Together these layers are called "mysia". Deep fascia also separates the groups of muscles into muscle compartments.


title: Skeletal muscle

text: Two types of sensory receptors found in muscles are muscle spindles, and Golgi tendon organs. Muscle spindles are stretch receptors located in the muscle belly. Golgi tendon organs are proprioceptors located at the myotendinous junction that inform of a muscle's tension.


title: Skeletal muscle

text: Skeletal muscle cells are the individual contractile cells within a muscle, and are often termed as muscle fibers. A single muscle such as the biceps in a young adult male contains around 253,000 muscle fibers.


title: Skeletal muscle

text: Skeletal muscle fibers are the only muscle cells that are multinucleated with the nuclei often referred to as myonuclei. This occurs during myogenesis with the fusion of myoblasts each contributing a nucleus. Fusion depends on muscle-specific proteins known as fusogens called "myomaker" and "myomerger".


title: Skeletal muscle

text: Many nuclei are needed by the skeletal muscle cell for the large amounts of proteins and enzymes needed to be produced for the cell's normal functioning.


title: Skeletal muscle

text: A single muscle fiber can contain from hundreds to thousands of nuclei. A muscle fiber for example in the human biceps with a length of 10 cm can have as many as 3000 nuclei. Unlike in a non-muscle cell where the nucleus is centrally positioned, the myonucleus is elongated and located close to the sarcolemma. The myonuclei are quite uniformly arranged along the fiber with each nucleus having its own "myonuclear domain" where it is responsible for supporting the volume of cytoplasm in that particular section of the myofiber.


title: Skeletal muscle

text: A group of muscle stem cells known as myosatellite cells, also "satellite cells" are found between the basement membrane and the sarcolemma of muscle fibers. These cells are normally quiescent but can be activated by exercise or pathology to provide additional myonuclei for muscle growth or repair.


title: Skeletal muscle

text: Muscles attach to tendons in a complex interface region known as the musculotendinous junction also known as the myotendinous junction, an area specialised for the primary transmission of force. At the muscle-tendon interface, force is transmitted from the sarcomeres in the muscle cells to the tendon. Muscles and tendons develop in close association, and after their joining at the myotendinous junction they constitute a dynamic unit for the transmission of force from muscle contraction to the skeletal system.


title: Skeletal muscle

text: Muscle architecture refers to the arrangement of muscle fibers relative to the axis of force generation, which runs from a muscle's origin to its insertion.


title: Skeletal muscle

text: The usual arrangements are types of parallel, and types of pennate muscle. In parallel muscles the fascicles run parallel to the axis of force generation, but the fascicles can vary in their relationship to one another, and to their tendons. These variations are seen in fusiform, strap, and convergent muscles. A convergent muscle has a triangular or fan-shape as the fibers converge at its insertion and are fanned out broadly at the origin. A less common example of a parallel muscle is a circular muscle such as the orbicularis oculi, in which the fibers are longitudinally arranged, but create a circle from origin to insertion. These different architectures, can cause variations in the tension that a muscle can create between its tendons.


title: Skeletal muscle

text: The fibers in pennate muscles run at an angle to the axis of force generation. This pennation angle reduces the effective force of any individual fiber, as it is effectively pulling off-axis. However, because of this angle, more fibers can be packed into the same muscle volume, increasing the physiological cross-sectional area (PCSA). This effect is known as fiber packing, and in terms of force generation, it more than overcomes the efficiency-loss of the off-axis orientation. The trade-off comes in overall speed of muscle shortening and in the total excursion. Overall muscle shortening speed is reduced compared to fiber shortening speed, as is the total distance of shortening. All of these effects scale with pennation angle; greater angles lead to greater force due to increased fiber packing and PCSA, but with greater losses in shortening speed and excursion. Types of pennate muscle are unipennate, bipennate, and multipennate. A unipennate muscle has similarly angled fibers that are on one side of a tendon. A bipennate muscle has fibers on two sides of a tendon. Multipennate muscles have fibers that are oriented at multiple angles along the force-generating axis, and this is the most general and most common architecture.


title: Skeletal muscle

text: Muscle fibers grow when exercised and shrink when not in use. This is due to the fact that exercise stimulates the increase in myofibrils which increase the overall size of muscle cells. Well exercised muscles can not only add more size but can also develop more mitochondria, myoglobin, glycogen and a higher density of capillaries. However muscle cells cannot divide to produce new cells, and as a result there are fewer muscle cells in an adult than in a newborn.


title: Skeletal muscle

text: There are a number of terms used in the naming of muscles including those relating to size, shape, action, location, their orientation, and their number of heads.


title: Skeletal muscle

text: Broadly there are two types of muscle fiber: Type I, which is slow, and Type II which are fast. Type II has two divisions of type IIA (oxidative), and type IIX (glycolytic), giving three main fiber types. These fibers have relatively distinct metabolic, contractile, and motor unit properties. The table below differentiates these types of properties. These types of properties—while they are partly dependent on the properties of individual fibers—tend to be relevant and measured at the level of the motor unit, rather than individual fiber.


title: Skeletal muscle

text: Traditionally, fibers were categorized depending on their varying color, which is a reflection of myoglobin content. Type I fibers appear red due to the high levels of myoglobin. Red muscle fibers tend to have more mitochondria and greater local capillary density. These fibers are more suited for endurance and are slow to fatigue because they use oxidative metabolism to generate ATP (adenosine triphosphate). Less oxidative Type II fibers are white due to relatively low myoglobin and a reliance on glycolytic enzymes.


title: Skeletal muscle

text: Fibers can also be classified on their twitch capabilities, into fast and slow twitch. These traits largely, but not completely, overlap the classifications based on color, ATPase, or MHC.


title: Skeletal muscle

text: Some authors define a fast twitch fiber as one in which the myosin can split ATP very quickly. These mainly include the ATPase type II and MHC type II fibers. However, fast twitch fibers also demonstrate a higher capability for electrochemical transmission of action potentials and a rapid level of calcium release and uptake by the sarcoplasmic reticulum. The fast twitch fibers rely on a well-developed, anaerobic, short term, glycolytic system for energy transfer and can contract and develop tension at 2–3 times the rate of slow twitch fibers. Fast twitch muscles are much better at generating short bursts of strength or speed than slow muscles, and so fatigue more quickly.


title: Skeletal muscle

text: The slow twitch fibers generate energy for ATP re-synthesis by means of a long term system of aerobic energy transfer. These mainly include the ATPase type I and MHC type I fibers. They tend to have a low activity level of ATPase, a slower speed of contraction with a less well developed glycolytic capacity. Fibers that become slow-twitch develop greater numbers of mitochondria and capillaries making them better for prolonged work.


title: Skeletal muscle

text: Individual muscles tend to be a mixture of various fiber types, but their proportions vary depending on the actions of that muscle. For instance, in humans, the quadriceps muscles contain ~52% type I fibers, while the soleus is ~80% type I. The orbicularis oculi muscle of the eye is only ~15% type I. Motor units within the muscle, however, have minimal variation between the fibers of that unit. It is this fact that makes the size principal of motor unit recruitment viable.


title: Skeletal muscle

text: It is believed there are no sex or age differences in fiber distribution; however, proportions of fiber types vary considerably from muscle to muscle and person to person. Among different species there is much variation in the proportions of muscle fiber types.


title: Skeletal muscle

text: People at the higher end of any sport tend to demonstrate patterns of fiber distribution e.g. endurance athletes show a higher level of type I fibers.


title: Skeletal muscle

text: Middle-distance event athletes show approximately equal distribution of the two types. This is also often the case for power athletes such as throwers and jumpers.


title: Skeletal muscle

text: It has been suggested that various types of exercise can induce changes in the fibers of a skeletal muscle.


title: Skeletal muscle

text: It is thought that if you perform endurance type events for a sustained period of time, some of the type IIX fibers transform into type IIA fibers. However, there is no consensus on the subject.


title: Skeletal muscle

text: It may well be that the type IIX fibers show enhancements of the oxidative capacity after high intensity endurance training which brings them to a level at which they are able to perform oxidative metabolism as effectively as slow twitch fibers of untrained subjects. This would be brought about by an increase in mitochondrial size and number and the associated related changes, not a change in fiber type.


title: Skeletal muscle

text: There are numerous methods employed for fiber-typing, and confusion between the methods is common among non-experts. Two commonly confused methods are histochemical staining for myosin ATPase activity and immunohistochemical staining for myosin heavy chain (MHC) type. Myosin ATPase activity is commonly—and correctly—referred to as simply "fiber type", and results from the direct assaying of ATPase activity under various conditions (e.g. pH). Myosin heavy chain staining is most accurately referred to as "MHC fiber type", e.g. "MHC IIa fibers", and results from determination of different MHC isoforms. These methods are closely related physiologically, as the MHC type is the primary determinant of ATPase activity. However, neither of these typing methods is directly metabolic in nature; they do not directly address oxidative or glycolytic capacity of the fiber.


title: Skeletal muscle

text: When "type I" or "type II" fibers are referred to generically, this most accurately refers to the sum of numerical fiber types (I vs. II) as assessed by myosin ATPase activity staining (e.g. "type II" fibers refers to type IIA + type IIAX + type IIXA ... etc.).


title: Skeletal muscle

text: Below is a table showing the relationship between these two methods, limited to fiber types found in humans. Subtype capitalization is used in fiber typing vs. MHC typing, and some ATPase types actually contain multiple MHC types. Also, a subtype B or b is not expressed in humans by either method. Early researchers believed humans to express a MHC IIb, which led to the ATPase classification of IIB. However, later research showed that the human MHC IIb was in fact IIx, indicating that the IIB is better named IIX. IIb is expressed in other mammals, so is still accurately seen (along with IIB) in the literature. Non human fiber types include true IIb fibers, IIc, IId, etc.


title: Skeletal muscle

text: Further fiber typing methods are less formally delineated, and exist on more of a spectrum. They tend to be focused more on metabolic and functional capacities (i.e., oxidative vs. glycolytic, fast vs. slow contraction time). As noted above, fiber typing by ATPase or MHC does not directly measure or dictate these parameters. However, many of the various methods are mechanistically linked, while others are correlated "in vivo". For instance, ATPase fiber type is related to contraction speed, because high ATPase activity allows faster crossbridge cycling. While ATPase activity is only one component of contraction speed, Type I fibers are "slow", in part, because they have low speeds of ATPase activity in comparison to Type II fibers. However, measuring contraction speed is not the same as ATPase fiber typing.


title: Skeletal muscle

text: Almost all multicellular animals depend on muscles to move. Generally, muscular systems of most multicellular animals comprise both slow-twitch and fast-twitch muscle fibers, though the proportions of each fiber type can vary across organisms and environments. The ability to shift their phenotypic fiber type proportions through training and responding to the environment has served organisms well when placed in changing environments either requiring short explosive movements (higher fast twitch proportion) or long duration of movement (higher slow twitch proportion) to survive. Bodybuilding has shown that changes in muscle mass and force production can change in a matter of months. Some examples of this variation are described below.


title: Skeletal muscle

text: American lobster, "Homarus americanus", has three fiber types including fast twitch fibers, slow-twitch and slow-tonic fibers. Slow-tonic is a slow twitch-fiber that can sustain longer contractions (tonic).  In lobsters, muscles in different body parts vary in the muscle fiber type proportions based on the purpose of the muscle group.


title: Skeletal muscle

text: In the early development of vertebrate embryos, growth and formation of muscle happens in successive waves or phases of myogenesis. The myosin heavy chain isotype is a major determinant of the specific fiber type. In zebrafish embryos, the first muscle fibers to form are the slow twitch fibers. These cells will undergo migration from their original location to form a monolayer of slow twitch muscle fibers. These muscle fibers undergo further differentiation as the embryo matures.


title: Skeletal muscle

text: In larger animals, different muscle groups will increasingly require different fiber type proportions within muscle for different purposes. Turtles, such as "Trachemys scripta elegans", have complimentary muscles within the neck that show a potential inverse trend of fiber type percentages (one muscle has high percentage of fast twitch, while the complementary muscle will have a higher percentage of slow twitch fibers). The complementary muscles of turtles had similar percentages of fiber types.


title: Skeletal muscle

text: Chimpanzee muscles are composed of 67% fast-twitch fibers and have a maximum dynamic force and power output 1.35 times higher than human muscles of similar size. Among mammals, there is a predominance of type II fibers utilizing glycolytic metabolism. Because of the discrepancy in fast twitch fibers compared to humans, chimpanzees outperform humans in power related tests. Humans, however, will do better at exercise in aerobic range requiring large metabolic costs such as walking (bipedalism).


title: Skeletal muscle

text: Across species, certain gene sequences have been preserved, but do not always have the same functional purpose. Within the zebrafish embryo, the "Prdm1" gene down-regulates the formation of new slow twitch fibers through direct and indirect mechanisms such as "Sox6" (indirect). In mice, the "Prdm1" gene is present but does not control slow muscle genes in mice through "Sox6".


title: Skeletal muscle

text: In addition to having a genetic basis, the composition of muscle fiber types is flexible and can vary with a number of different environmental factors. This plasticity can, arguably, be the strongest evolutionary advantage among organisms with muscle.


title: Skeletal muscle

text: In fish, different fiber types are expressed at different water temperatures. Cold temperatures require more efficient metabolism within muscle and fatigue resistance is important. While in more tropical environments, fast powerful movements (from higher fast-twitch proportions) may prove more beneficial in the long run.


title: Skeletal muscle

text: In rodents such as rats, the transitory nature of their muscle is highly prevalent. They have high percentage of hybrid muscle fibers and have up to 60% in fast-to-slow transforming muscle.


title: Skeletal muscle

text: Environmental influences such as diet, exercise and lifestyle types have a pivotal role in proportions of fiber type in humans. Aerobic exercise will shift the proportions towards slow twitch fibers, while explosive powerlifting and sprinting will transition fibers towards fast twitch. In animals, "exercise training" will look more like the need for long durations of movement or short explosive movements to escape predators or catch prey.


title: Skeletal muscle

text: Skeletal muscle exhibits a distinctive banding pattern when viewed under the microscope due to the arrangement of two contractile proteins myosin, and actin – that are two of the myofilaments in the myofibrils. The myosin forms the thick filaments, and actin forms the thin filaments, and are arranged in repeating units called sarcomeres. The interaction of both proteins results in muscle contraction.


title: Skeletal muscle

text: The sarcomere is attached to other organelles such as the mitochondria by intermediate filaments in the cytoskeleton. The costamere attaches the sarcomere to the sarcolemma.


title: Skeletal muscle

text: Every single organelle and macromolecule of a muscle fiber is arranged to ensure that it meets desired functions. The cell membrane is called the sarcolemma with the cytoplasm known as the sarcoplasm. In the sarcoplasm are the myofibrils. The myofibrils are long protein bundles about one micrometer in diameter. Pressed against the inside of the sarcolemma are the unusual flattened myonuclei. Between the myofibrils are the mitochondria.


title: Skeletal muscle

text: While the muscle fiber does not have smooth endoplasmic cisternae, it contains sarcoplasmic reticulum. The sarcoplasmic reticulum surrounds the myofibrils and holds a reserve of the calcium ions needed to cause a muscle contraction. Periodically, it has dilated end sacs known as terminal cisternae. These cross the muscle fiber from one side to the other. In between two terminal cisternae is a tubular infolding called a transverse tubule (T tubule). T tubules are the pathways for action potentials to signal the sarcoplasmic reticulum to release calcium, causing a muscle contraction. Together, two terminal cisternae and a transverse tubule form a triad.


title: Skeletal muscle

text: All muscles are derived from paraxial mesoderm. During embryonic development in the process of somitogenesis the paraxial mesoderm is divided along the embryo's length to form somites, corresponding to the segmentation of the body most obviously seen in the vertebral column. Each somite has three divisions, sclerotome (which forms vertebrae), dermatome (which forms skin), and myotome (which forms muscle). The myotome is divided into two sections, the epimere and hypomere, which form epaxial and hypaxial muscles, respectively. The only epaxial muscles in humans are the erector spinae and small vertebral muscles, and are innervated by the dorsal rami of the spinal nerves. All other muscles, including those of the limbs are hypaxial, and innervated by the ventral rami of the spinal nerves.


title: Skeletal muscle

text: During development, myoblasts (muscle progenitor cells) either remain in the somite to form muscles associated with the vertebral column or migrate out into the body to form all other muscles. Myoblast migration is preceded by the formation of connective tissue frameworks, usually formed from the somatic lateral plate mesoderm. Myoblasts follow chemical signals to the appropriate locations, where they fuse into elongated multinucleated skeletal muscle cells.


title: Skeletal muscle

text: Between the tenth and the eighteenth weeks of gestation, all muscle cells have fast myosin heavy chains; two myotube types become distinguished in the developing fetus – both expressing fast chains but one expressing fast and slow chains. Between 10 and 40 per cent of the fibers express the slow myosin chain.


title: Skeletal muscle

text: Fiber types are established during embryonic development and are remodelled later in the adult by neural and hormonal influences. The population of satellite cells present underneath the basal lamina is necessary for the postnatal development of muscle cells.


title: Skeletal muscle

text: The primary function of muscle is contraction. Following contraction, skeletal muscle functions as an endocrine organ by secreting myokines – a wide range of cytokines and other peptides that act as signalling molecules. Myokines in turn are believed to mediate the health benefits of exercise. Myokines are secreted into the bloodstream after muscle contraction. Interleukin 6 (IL-6) is the most studied myokine, other muscle contraction-induced myokines include BDNF, FGF21, and SPARC.


title: Skeletal muscle

text: Muscle also functions to produce body heat. Muscle contraction is responsible for producing 85% of the body's heat. This heat produced is as a by-product of muscular activity, and is mostly wasted. As a homeostatic response to extreme cold, muscles are signaled to trigger contractions of shivering in order to generate heat.


title: Skeletal muscle

text: Contraction is achieved by the muscle's structural unit, the muscle fiber, and by its functional unit, the motor unit. Muscle fibers are excitable cells stimulated by motor neurons. The motor unit consists of a motor neuron and the many fibers that it makes contact with. A single muscle is stimulated by many motor units. Muscle fibers are


title: Skeletal muscle

text: subject to depolarization by the neurotransmitter acetylcholine, released by the motor neurons at the neuromuscular junctions.


title: Skeletal muscle

text: In addition to the actin and myosin myofilaments in the myofibrils that make up the contractile sarcomeres, there are two other important regulatory proteins – troponin and tropomyosin, that make muscle contraction possible. These proteins are associated with actin and cooperate to prevent its interaction with myosin. Once a cell is sufficiently stimulated, the cell's sarcoplasmic reticulum releases ionic calcium (Ca), which then interacts with the regulatory protein troponin. Calcium-bound troponin undergoes a conformational change that leads to the movement of tropomyosin, subsequently exposing the myosin-binding sites on actin. This allows for myosin and actin ATP-dependent cross-bridge cycling and shortening of the muscle.


title: Skeletal muscle

text: Excitation contraction coupling is the process by which a muscular action potential in the muscle fiber causes the myofibrils to contract. This process relies on a direct coupling between the sarcoplasmic reticulum calcium release channel RYR1 (ryanodine receptor 1), and voltage-gated L-type calcium channels (identified as dihydropyridine receptors, DHPRs). DHPRs are located on the sarcolemma (which includes the surface sarcolemma and the transverse tubules), while the RyRs reside across the SR membrane. The close apposition of a transverse tubule and two SR regions containing RyRs is described as a triad and is predominantly where excitation–contraction coupling takes place. Excitation–contraction coupling occurs when depolarization of skeletal muscle cell results in a muscle action potential, which spreads across the cell surface and into the muscle fiber's network of T-tubules, thereby depolarizing the inner portion of the muscle fiber. Depolarization of the inner portions activates dihydropyridine receptors in the terminal cisternae, which are close to ryanodine receptors in the adjacent sarcoplasmic reticulum. The activated dihydropyridine receptors physically interact with ryanodine receptors to activate them via foot processes (involving conformational changes that allosterically activates the ryanodine receptors). As the ryanodine receptors open, is released from the sarcoplasmic reticulum into the local junctional space and diffuses into the bulk cytoplasm to cause a calcium spark. Note that the sarcoplasmic reticulum has a large calcium buffering capacity partially due to a calcium-binding protein called calsequestrin. The near synchronous activation of thousands of calcium sparks by the action potential causes a cell-wide increase in calcium giving rise to the upstroke of the calcium transient. The released into the cytosol binds to Troponin C by the actin filaments, to allow crossbridge cycling, producing force and, in some situations, motion. The sarco/endoplasmic reticulum calcium-ATPase (SERCA) actively pumps back into the sarcoplasmic reticulum. As declines back to resting levels, the force declines and relaxation occurs.


title: Skeletal muscle

text: The efferent leg of the peripheral nervous system is responsible for conveying commands to the muscles and glands, and is ultimately responsible for voluntary movement. Nerves move muscles in response to voluntary and autonomic (involuntary) signals from the brain. Deep muscles, superficial muscles, and internal muscles all correspond with dedicated regions in the primary motor cortex of the brain, directly anterior to the central sulcus that divides the frontal and parietal lobes.


title: Skeletal muscle

text: In addition, muscles react to reflexive nerve stimuli that do not always send signals all the way to the brain. In this case, the signal from the afferent fiber does not reach the brain, but produces the reflexive movement by direct connections with the efferent nerves in the spine. However, the majority of muscle activity is volitional, and the result of complex interactions between various areas of the brain.


title: Skeletal muscle

text: Nerves that control skeletal muscles in mammals correspond with neuron groups along the primary motor cortex of the brain's cerebral cortex. Commands are routed through the basal ganglia and are modified by input from the cerebellum before being relayed through the pyramidal tract to the spinal cord and from there to the motor end plate at the muscles. Along the way, feedback, such as that of the extrapyramidal system contribute signals to influence muscle tone and response.


title: Skeletal muscle

text: Deeper muscles such as those involved in posture often are controlled from nuclei in the brain stem and basal ganglia.


title: Skeletal muscle

text: In skeletal muscles, muscle spindles convey information about the degree of muscle length and stretch to the central nervous system to assist in maintaining posture and joint position. The sense of where our bodies are in space is called proprioception, the perception of body awareness, the "unconscious" awareness of where the various regions of the body are located at any one time. Several areas in the brain coordinate movement and position with the feedback information gained from proprioception. The cerebellum and red nucleus in particular continuously sample position against movement and make minor corrections to assure smooth motion.


title: Skeletal muscle

text: Muscular activity accounts for much of the body's energy consumption. All muscle cells produce adenosine triphosphate (ATP) molecules which are used to power the movement of the myosin heads. Muscles have a short-term store of energy in the form of creatine phosphate which is generated from ATP and can regenerate ATP when needed with creatine kinase. Muscles also keep a storage form of glucose in the form of glycogen. Glycogen can be rapidly converted to glucose when energy is required for sustained, powerful contractions. Within the voluntary skeletal muscles, the glucose molecule can be metabolized anaerobically in a process called glycolysis which produces two ATP and two lactic acid molecules in the process (note that in aerobic conditions, lactate is not formed; instead pyruvate is formed and transmitted through the citric acid cycle). Muscle cells also contain globules of fat, which are used for energy during aerobic exercise. The aerobic energy systems take longer to produce the ATP and reach peak efficiency, and requires many more biochemical steps, but produces significantly more ATP than anaerobic glycolysis. Cardiac muscle on the other hand, can readily consume any of the three macronutrients (protein, glucose and fat) aerobically without a 'warm up' period and always extracts the maximum ATP yield from any molecule involved. The heart, liver and red blood cells will also consume lactic acid produced and excreted by skeletal muscles during exercise.


title: Skeletal muscle

text: At rest it consumes 54.4 kJ/kg (13.0 kcal/kg) per day. This is larger than adipose tissue (fat) at 18.8 kJ/kg (4.5 kcal/kg), and bone at 9.6 kJ/kg (2.3 kcal/kg).


title: Skeletal muscle

text: The efficiency of human muscle has been measured (in the context of rowing and cycling) at 18% to 26%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost, as can be calculated from oxygen consumption. This low efficiency is the result of about 40% efficiency of generating ATP from food energy, losses in converting energy from ATP into mechanical work inside the muscle, and mechanical losses inside the body. The latter two losses are dependent on the type of exercise and the type of muscle fibers being used (fast-twitch or slow-twitch). For an overall efficiency of 20 percent, one watt of mechanical power is equivalent to 4.3 kcal per hour. For example, one manufacturer of rowing equipment calibrates its rowing ergometer to count burned calories as equal to four times the actual mechanical work, plus 300 kcal per hour, this amounts to about 20 percent efficiency at 250 watts of mechanical output. The mechanical energy output of a cyclic contraction can depend upon many factors, including activation timing, muscle strain trajectory, and rates of force rise & decay. These can be synthesized experimentally using work loop analysis.


title: Skeletal muscle

text: Muscle strength is a result of three overlapping factors: "physiological strength" (muscle size, cross sectional area, available crossbridging, responses to training), "neurological strength" (how strong or weak is the signal that tells the muscle to contract), and "mechanical strength" (muscle's force angle on the lever, moment arm length, joint capabilities).


title: Skeletal muscle

text: Vertebrate muscle typically produces approximately of force per square centimeter of muscle cross-sectional area when isometric and at optimal length. Some invertebrate muscles, such as in crab claws, have much longer sarcomeres than vertebrates, resulting in many more sites for actin and myosin to bind and thus much greater force per square centimeter at the cost of much slower speed. The force generated by a contraction can be measured non-invasively using either mechanomyography or phonomyography, be measured in vivo using tendon strain (if a prominent tendon is present), or be measured directly using more invasive methods.


title: Skeletal muscle

text: The strength of any given muscle, in terms of force exerted on the skeleton, depends upon length, shortening speed, cross sectional area, pennation, sarcomere length, myosin isoforms, and neural activation of motor units. Significant reductions in muscle strength can indicate underlying pathology, with the chart at right used as a guide.


title: Skeletal muscle

text: The "maximum holding time" for a contracted muscle depends on its supply of energy and is stated by Rohmert's law to exponentially decay from the beginning of exertion.


title: Skeletal muscle

text: Since three factors affect muscular strength simultaneously and muscles never work individually, it is misleading to compare strength in individual muscles, and state that one is the "strongest". But below are several muscles whose strength is noteworthy for different reasons.


title: Skeletal muscle

text: Muscle force is proportional to physiological cross-sectional area (PCSA), and muscle velocity is proportional to muscle fiber length. The torque around a joint, however, is determined by a number of biomechanical parameters, including the distance between muscle insertions and pivot points, muscle size and architectural gear ratio. Muscles are normally arranged in opposition so that when one group of muscles contracts, another group relaxes or lengthens. Antagonism in the transmission of nerve impulses to the muscles means that it is impossible to fully stimulate the contraction of two antagonistic muscles at any one time. During ballistic motions such as throwing, the antagonist muscles act to 'brake' the agonist muscles throughout the contraction, particularly at the end of the motion. In the example of throwing, the chest and front of the shoulder (anterior deltoid) contract to pull the arm forward, while the muscles in the back and rear of the shoulder (posterior deltoid) also contract and undergo eccentric contraction to slow the motion down to avoid injury. Part of the training process is learning to relax the antagonist muscles to increase the force input of the chest and anterior shoulder.


title: Skeletal muscle

text: Contracting muscles produce vibration and sound. Slow twitch fibers produce 10 to 30 contractions per second (10 to 30 Hz). Fast twitch fibers produce 30 to 70 contractions per second (30 to 70 Hz). The vibration can be witnessed and felt by highly tensing one's muscles, as when making a firm fist. The sound can be heard by pressing a highly tensed muscle against the ear, again a firm fist is a good example. The sound is usually described as a rumbling sound. Some individuals can voluntarily produce this rumbling sound by contracting the tensor tympani muscle of the middle ear. The rumbling sound can also be heard when the neck or jaw muscles are highly tensed.


title: Skeletal muscle

text: Skeletal muscle fiber-type phenotype in adult animals is regulated by several independent signaling pathways. These include pathways involved with the Ras/mitogen-activated protein kinase (MAPK) pathway, calcineurin, calcium/calmodulin-dependent protein kinase IV, and the peroxisome proliferator γ coactivator 1 (PGC-1). The Ras/MAPK signaling pathway links the motor neurons and signaling systems, coupling excitation and transcription regulation to promote the nerve-dependent induction of the slow program in regenerating muscle. Calcineurin, a Ca/calmodulin-activated phosphatase implicated in nerve activity-dependent fiber-type specification in skeletal muscle, directly controls the phosphorylation state of the transcription factor NFAT, allowing for its translocation to the nucleus and leading to the activation of slow-type muscle proteins in cooperation with myocyte enhancer factor 2 (MEF2) proteins and other regulatory proteins. Ca2+/calmodulin-dependent protein kinase activity is also upregulated by slow motor neuron activity, possibly because it amplifies the slow-type calcineurin-generated responses by promoting MEF2 transactivator functions and enhancing oxidative capacity through stimulation of mitochondrial biogenesis.


title: Skeletal muscle

text: Contraction-induced changes in intracellular calcium or reactive oxygen species provide signals to diverse pathways that include the MAPKs, calcineurin and calcium/calmodulin-dependent protein kinase IV to activate transcription factors that regulate gene expression and enzyme activity in skeletal muscle.


title: Skeletal muscle

text: PGC1-α (PPARGC1A), a transcriptional coactivator of nuclear receptors important to the regulation of a number of mitochondrial genes involved in oxidative metabolism, directly interacts with MEF2 to synergistically activate selective slow twitch (ST) muscle genes and also serves as a target for calcineurin signaling. A peroxisome proliferator-activated receptor δ (PPARδ)-mediated transcriptional pathway is involved in the regulation of the skeletal muscle fiber phenotype. Mice that harbor an activated form of PPARδ display an "endurance" phenotype, with a coordinated increase in oxidative enzymes and mitochondrial biogenesis and an increased proportion of ST fibers. Thus—through functional genomics—calcineurin, calmodulin-dependent kinase, PGC-1α, and activated PPARδ form the basis of a signaling network that controls skeletal muscle fiber-type transformation and metabolic profiles that protect against insulin resistance and obesity.


title: Skeletal muscle

text: The transition from aerobic to anaerobic metabolism during intense work requires that several systems are rapidly activated to ensure a constant supply of ATP for the working muscles. These include a switch from fat-based to carbohydrate-based fuels, a redistribution of blood flow from nonworking to exercising muscles, and the removal of several of the by-products of anaerobic metabolism, such as carbon dioxide and lactic acid. Some of these responses are governed by transcriptional control of the fast twitch (FT) glycolytic phenotype. For example, skeletal muscle reprogramming from an ST glycolytic phenotype to an FT glycolytic phenotype involves the Six1/Eya1 complex, composed of members of the Six protein family. Moreover, the hypoxia-inducible factor 1-α (HIF1A) has been identified as a master regulator for the expression of genes involved in essential hypoxic responses that maintain ATP levels in cells. Ablation of HIF-1α in skeletal muscle was associated with an increase in the activity of rate-limiting enzymes of the mitochondria, indicating that the citric acid cycle and increased fatty acid oxidation may be compensating for decreased flow through the glycolytic pathway in these animals. However, hypoxia-mediated HIF-1α responses are also linked to the regulation of mitochondrial dysfunction through the formation of excessive reactive oxygen species in mitochondria.


title: Skeletal muscle

text: Other pathways also influence adult muscle character. For example, physical force inside a muscle fiber may release the transcription factor serum response factor from the structural protein titin, leading to altered muscle growth.


title: Skeletal muscle

text: Physical exercise is often recommended as a means of improving motor skills, fitness, muscle and bone strength, and joint function. Exercise has several effects upon muscles, connective tissue, bone, and the nerves that stimulate the muscles. One such effect is muscle hypertrophy, an increase in size of muscle due to an increase in the number of muscle fibers or cross-sectional area of myofibrils. Muscle changes depend on the type of exercise used.


title: Skeletal muscle

text: Generally, there are two types of exercise regimes, aerobic and anaerobic. Aerobic exercise (e.g. marathons) involves activities of low intensity but long duration, during which the muscles used are below their maximal contraction strength. Aerobic activities rely on aerobic respiration (i.e. citric acid cycle and electron transport chain) for metabolic energy by consuming fat, protein, carbohydrates, and oxygen. Muscles involved in aerobic exercises contain a higher percentage of Type I (or slow-twitch) muscle fibers, which primarily contain mitochondrial and oxidation enzymes associated with aerobic respiration. On the contrary, anaerobic exercise is associated with activities of high intensity but short duration, such as sprinting or weight lifting. The anaerobic activities predominately use Type II, fast-twitch, muscle fibers. Type II muscle fibers rely on glucogenesis for energy during anaerobic exercise. During anaerobic exercise, type II fibers consume little oxygen, protein and fat, produce large amounts of lactic acid and are fatigable. Many exercises are partially aerobic and anaerobic; for example, soccer and rock climbing.


title: Skeletal muscle

text: The presence of lactic acid has an inhibitory effect on ATP generation within the muscle. It can even stop ATP production if the intracellular concentration becomes too high. However, endurance training mitigates the buildup of lactic acid through increased capillarization and myoglobin. This increases the ability to remove waste products, like lactic acid, out of the muscles in order to not impair muscle function. Once moved out of muscles, lactic acid can be used by other muscles or body tissues as a source of energy, or transported to the liver where it is converted back to pyruvate. In addition to increasing the level of lactic acid, strenuous exercise results in the loss of potassium ions in muscle. This may facilitate the recovery of muscle function by protecting against fatigue.


title: Skeletal muscle

text: Delayed onset muscle soreness is pain or discomfort that may be felt one to three days after exercising and generally subsides two to three days later. Once thought to be caused by lactic acid build-up, a more recent theory is that it is caused by tiny tears in the muscle fibers caused by eccentric contraction, or unaccustomed training levels. Since lactic acid disperses fairly rapidly, it could not explain pain experienced days after exercise.


title: Skeletal muscle

text: Diseases of skeletal muscle are termed myopathies, while diseases of nerves are called neuropathies. Both can affect muscle function or cause muscle pain, and fall under the umbrella of neuromuscular disease. The cause of many myopathies is attributed to mutations in the various associated muscle proteins. Some inflammatory myopathies include polymyositis and inclusion body myositis


title: Skeletal muscle

text: Neuromuscular diseases affect the muscles and their nervous control. In general, problems with nervous control can cause spasticity or paralysis, depending on the location and nature of the problem. A number of movement disorders are caused by neurological disorders such as Parkinson's disease and Huntington's disease where there is central nervous system dysfunction.


title: Skeletal muscle

text: Symptoms of muscle diseases may include weakness, spasticity, myoclonus and myalgia. Diagnostic procedures that may reveal muscular disorders include testing creatine kinase levels in the blood and electromyography (measuring electrical activity in muscles). In some cases, muscle biopsy may be done to identify a myopathy, as well as genetic testing to identify DNA abnormalities associated with specific myopathies and dystrophies.


title: Skeletal muscle

text: A non-invasive elastography technique that measures muscle noise is undergoing experimentation to provide a way of monitoring neuromuscular disease. The sound produced by a muscle comes from the shortening of actomyosin filaments along the axis of the muscle. During contraction, the muscle shortens along its length and expands across its width, producing vibrations at the surface.


title: Skeletal muscle

text: Independent of strength and performance measures, muscles can be induced to grow larger by a number of factors, including hormone signaling, developmental factors, strength training, and disease. Contrary to popular belief, the number of muscle fibres cannot be increased through exercise. Instead, muscles grow larger through a combination of muscle cell growth as new protein filaments are added along with additional mass provided by undifferentiated satellite cells alongside the existing muscle cells.


title: Skeletal muscle

text: Biological factors such as age and hormone levels can affect muscle hypertrophy. During puberty in males, hypertrophy occurs at an accelerated rate as the levels of growth-stimulating hormones produced by the body increase. Natural hypertrophy normally stops at full growth in the late teens. As testosterone is one of the body's major growth hormones, on average, men find hypertrophy much easier to achieve than women. Taking additional testosterone or other anabolic steroids will increase muscular hypertrophy.


title: Skeletal muscle

text: Muscular, spinal and neural factors all affect muscle building. Sometimes a person may notice an increase in strength in a given muscle even though only its opposite has been subject to exercise, such as when a bodybuilder finds her left biceps stronger after completing a regimen focusing only on the right biceps. This phenomenon is called cross education.


title: Skeletal muscle

text: Every day between one and two percent of muscle is broken down and rebuilt. Inactivity, malnutrition, disease, and aging can increase the breakdown leading to muscle atrophy or sarcopenia. Sarcopenia is commonly an age-related process that can cause frailty and its consequences. A decrease in muscle mass may be accompanied by a smaller number and size of the muscle cells as well as lower protein content.


title: Skeletal muscle

text: Human spaceflight, involving prolonged periods of immobilization and weightlessness is known to result in muscle weakening and atrophy resulting in a loss of as much as 30% of mass in some muscles. Such consequences are also noted in some mammals following hibernation.


title: Skeletal muscle

text: Many diseases and conditions including cancer, AIDS, and heart failure can cause muscle loss known as cachexia.


title: Skeletal muscle

text: Myopathies have been modeled with cell culture systems of muscle from healthy or diseased tissue biopsies. Another source of skeletal muscle and progenitors is provided by the directed differentiation of pluripotent stem cells.


title: Skeletal muscle

text: Research on skeletal muscle properties uses many techniques. Electrical muscle stimulation is used to determine force and contraction speed at different frequencies related to fiber-type composition and mix within an individual muscle group. In vitro muscle testing is used for more complete characterization of muscle properties.


title: Skeletal muscle

text: The electrical activity associated with muscle contraction is measured via electromyography (EMG). Skeletal muscle has two physiological responses: relaxation and contraction. The mechanisms for which these responses occur generate electrical activity measured by EMG. Specifically, EMG can measure the action potential of a skeletal muscle, which occurs from the hyperpolarization of the motor axons from nerve impulses sent to the muscle. EMG is used in research for determining if the skeletal muscle of interest is being activated, the amount of force generated, and an indicator of muscle fatigue. The two types of EMG are intra-muscular EMG and the most common, surface EMG. The EMG signals are much greater when a skeletal muscle is contracting verses relaxing. However, for smaller and deeper skeletal muscles the EMG signals are reduced and therefore are viewed as a less valued technique for measuring the activation. In research using EMG, a maximal voluntary contraction (MVC) is commonly performed on the skeletal muscle of interest, to have reference data for the rest of the EMG recordings during the main experimental testing for that same skeletal muscle.


title: Denzel Curry

text: Denzel Rae Don Curry (born February 16, 1995) is an American rapper and singer. Born and raised in Carol City, Florida, Curry started rapping while in the sixth grade and began working on his first mixtape in 2011. Influenced by underground Florida rapper SpaceGhostPurrp, the mixtape was later featured on Purrp's social media, giving Curry attention in the local music scene and resulting in him joining Purrp's hip-hop collective Raider Klan.


title: Denzel Curry

text: Curry left Raider Klan in 2013, releasing his debut studio album, "Nostalgic 64", in September of that year, while still in high school. He has since released three extended plays: "32 Zel/Planet Shrooms" in 2015, "13" in 2017, and "Unlocked" (a collaboration with Kenny Beats) in 2020, and four studio albums: "Imperial" in 2016, "Ta13oo" in 2018, "Zuu" in 2019, and "Melt My Eyez See Your Future" in 2022. "Ta13oo", "Zuu", and "Melt My Eyez" debuted at numbers 28, 32, and 51 on the "Billboard" 200 chart, respectively, with "Melt My Eyez" returning at number 17 after the release of an extended edition. All of his projects have garnered significant critical acclaim.


title: Denzel Curry

text: Denzel Rae Don Curry was born on February 16, 1995, in Carol City, Florida. He is of Bahamian descent through both his mother and father. Curry started down an artist's path with early poetry ambitions in elementary school before he began rapping in the sixth grade. His time was spent at a local Boys & Girls Clubs of America chapter where he challenged others to rap battles. He attended Miami's Design and Architecture High School for two years before being expelled. Curry then attended Miami Carol City Senior High School, where he started working on "Nostalgic 64" while still attending class. In a 2018 interview with "The Breakfast Club", Curry disclosed that he was molested by an unnamed older male during his childhood.


title: Denzel Curry

text: On September 24, 2011, Curry released his first mixtape, titled "King Remembered Underground Tape 1991–1995". The whole project that Curry posted was later included on SpaceGhostPurrp's page, which prompted the birth of Denzel's music career. Following the release of Curry's first mixtape, Curry became a member of SpaceGhostPurrp's hip hop group, Raider Klan.


title: Denzel Curry

text: In 2012, he released his second mixtape, titled "King of the Mischievous South Vol. 1 Underground Tape 1996", which caught the attention of fellow American rapper Earl Sweatshirt and other members of the Odd Future label.


title: Denzel Curry

text: Curry's third mixtape, titled "Strictly for My R.V.I.D.X.R.Z.", was released after the death of Trayvon Martin, who also lived in Carol City and went to the same high school as Denzel Curry. His style of rap and the name of the record were heavily inspired by Tupac Shakur.


title: Denzel Curry

text: In late 2012, Curry met his manager Mark Maturah, and under his guidance, released his first studio single, "Dark & Violent", featuring J. K. The Reaper and Nell, to SoundCloud.


title: Denzel Curry

text: In 2021, a mixtape named "Curry Wuz Here" surfaced on YouTube, and the release date was claimed to be January 16, 2011.


title: Denzel Curry

text: The group Raider Klan was disbanded, which led to Curry deciding to embark on his solo rap career. On September 3, 2013, Curry released his debut full-length album, titled "Nostalgic 64". The album features guest appearances from JK the Reaper, Lil Ugly Mane, Mike G, Nell, Robb Bank$, Stephen A. Clark, and Yung Simmie, among others. In 2014, Curry was featured on Deniro Farrar's track, called "Bow Down" (included from Farrar's "Rebirth" EP) and Curry was featured on Dillon Cooper's track, called "Eyes of the World" (included from Cooper's "X:XX" mixtape). Curry himself has stated that he was heavily inspired by Outkast's record, Aquemini, saying he drew the cover for Nostalgic 64 while listening to the record. He also was inspired by Goodie Mob and CeeLo Green, and other southern music.


title: Denzel Curry

text: On June 9, 2015, Curry released his first double EP, "32 Zel/Planet Shrooms", which contained his breakout single "Ultimate". The song went viral, and was played over Bottle Flip videos among others. It has amassed over 175 million streams on Spotify and earned 65 million views on YouTube. His first release in 2016 was the single "Flying Nimbus".


title: Denzel Curry

text: His second full-length album, titled "Imperial", was released on March 9, 2016, then re-released later on Spotify as the deluxe version on October 14, 2016.


title: Denzel Curry

text: In June 2016, Curry appeared in "XXL" magazine as part of their 2016 Freshmen Class. As part of this appearance, Curry performed a 'freshman cypher' alongside Lil Uzi Vert, Lil Yachty, 21 Savage, and Kodak Black. As of March 2021, this cypher has received over 180 million YouTube views, by far the most for the XXL channel.


title: Denzel Curry

text: On May 13, 2017, Curry uploaded a track titled "Hate Government [demo]" to his SoundCloud account. In the weeks that followed, he released two more demos for songs titled "Equalizer [demo]" and "Zeltron 6 Billion" featuring Lil Ugly Mane. After these releases as well as a series of cryptic posts on social media (seemingly portraying another alter ego called Zeltron), he released an EP titled "13" on June 25, 2017. All of the demo tracks were included on the EP as well as two other new songs. On August 18, 2017, Curry released another song called "Skywalker." Later that year, on September 22, a remastered version of "32 Zel" was released, including a remix of "Ultimate" featuring Juicy J.


title: Denzel Curry

text: Since he started releasing demos for songs on "13", Curry made several mentions of his third studio album titled, "Ta13oo". "13" serves as a sampler to "Ta13oo", and no release date for the album was announced. On February 28, 2018, he appeared on the song "Kristi," by artist ASAP Ferg, which also featured IDK. It was first performed live in Austin, TX on March 10, during their collaborative tour. On March 16, 2018, he uploaded the song "Uh Huh," once again featuring IDK, onto his official YouTube channel.


title: Denzel Curry

text: On April 2, 2018, Curry released the lead single off of "Ta13oo" titled "Sumo" on Zane Lowe's Beats 1 radio show. On May 24, 2018, Curry released the second single off the album titled, "Percs". Curry then released the third single titled, "Clout Cobain", on July 13, 2018, and announced that his album "Ta13oo", would be released in three acts: The first act, "Light", was released on July 25, followed by "Gray" on July 26, and "Dark" on July 27. Each previously-released single represents one of the album's acts, as "Sumo" represents "Light", "Clout Cobain" represents "Gray", and "Percs" represents "Dark", which come together cohesively to form "Ta13oo".


title: Denzel Curry

text: On February 14, 2019, Curry performed a cover of "Bulls on Parade" by Rage Against the Machine on the Australian radio station Triple J as part of Like a Version, which was met with widespread acclaim. His cover went on to place 5th on that year's Triple J Hottest 100 countdown.


title: Denzel Curry

text: On May 8, 2019, Curry released "Ricky", his first single since the release of "Ta13oo". The song is titled after his father, whom the song is inspired by. On May 22, 2019, Curry released a second single title "Speedboat" and announced the release of his next album "Zuu" for May 31, 2019.


title: Denzel Curry

text: On July 15, 2019, Curry made his television debut on "The Tonight Show Starring Jimmy Fallon", performing a medley of "Ricky" and "Wish" from his album "Zuu". He also revealed that he had cut his signature dreadlocks.


title: Denzel Curry

text: On January 6, 2020, Curry released a project titled "13lood 1n + 13lood Out", featuring fellow rappers Ghostemane, Xavier Wulf, ZillaKami and AK of The Underachievers. The project was initially announced in November 2018.


title: Denzel Curry

text: On February 7, 2020, Curry released "Unlocked," an EP collaboration with Kenny Beats. The release was accompanied with an animated short film. In August 2020, Curry was featured on the soundtrack to the "Madden NFL 21" game, on the song "Lemonade", with singer Yungblud. In October 2020, Curry was featured on $NOT's track "Sangria".


title: Denzel Curry

text: On March 5, 2021, Curry released "Unlocked 1.5", a remix of his previous collaboration with Kenny Beats. The remix album features new production from Robert Glasper, The Alchemist, Georgia Anne Muldrow, Sango, Jay Versace, Godmode, and Charlie Heat, as well as new features from Smino, Joey Bada$$, and Benny the Butcher among others.


title: Denzel Curry

text: Curry was featured on the September 2021 song "Bleach", released on rapper ZillaKami's debut album, DOG BOY.


title: Denzel Curry

text: Curry collaborated on the track "Dynasties and Dystopia" from the Netflix series "Arcane", alongside Gizzle and Bren Joy.


title: Denzel Curry

text: On January 5, 2022, the official trailer for Curry's fifth studio album, titled "Melt My Eyez See Your Future", was uploaded to his YouTube channel. It was revealed that the album would contain guest appearances from artists such as T-Pain, 6lack, Slowthai, Rico Nasty, J.I.D, and Thundercat, among others. Curry said the project would feature a new, more mature sound, different from his previous works: "Y'all are not going to hear the same type of Denzel anymore." On January 24, a single titled "Walkin", along with a Western-inspired music video directed by Adrian Villagomez, was released. Curry also said the album "is made up of everything that I couldn't [include] on "Ta13oo" or "Imperial" because I was going through depression [and] anger issues", and would take inspiration from traditional hip-hop, drum and bass, trap, poetry, and jazz. The same day, a North American and European tour promoting the album (with guest acts Kenny Mason, Mike Dimes, Redveil, and PlayThatBoiZay) was announced. On February 24, Curry released another single from the upcoming album, "Zatoichi" featuring Slowthai. It was accompanied by a music video also directed by Adrian Villagomez. On March 18, Curry announced the album would be released on March 25. On March 21, a third single, "Troubles" featuring T-Pain, was released along with a music video. The album was released on March 25, 2022. It debuted at number 51 on the "Billboard" 200 chart, and at number 23 on the "Billboard" Top R&B/Hip-Hop Albums chart.


title: Denzel Curry

text: Curry recorded a song featuring rapper Reason, "1st Quarter", as a contribution to Apple Music's "collection of exclusively commissioned new songs from Black creatives", titled "Juneteenth 2022: Freedom Songs". He commented: "It's an accomplishment to make it through the first quarter of my life. Especially as a Black man in America".


title: Denzel Curry

text: Curry's song featuring PlayThatBoiZay, "Let It All Hang Out", was included in "Elvis"—a biographical movie about Elvis Presley that premiered in June 2022—as well as on the movie's soundtrack album.


title: Denzel Curry

text: On June 24, 2022, a collaboration between Dot da Genius, JID, Curry, and Kid Cudi, titled "Talk About Me", was released, along with a music video directed by Cole Bennett.


title: Denzel Curry

text: On June 29, 2022, Curry performed an NPR Tiny Desk Concert. On July 21, he performed "Walkin" on "The Tonight Show Starring Jimmy Fallon".


title: Denzel Curry

text: On September 30, 2022, Curry released Melt My Eyez See Your Future (The Extended Edition). The album features reimagined versions of songs from the original album with live instrumentation performed by the Cold Blooded Soul Band, which performed with Curry on his NPR Tiny Desk Concert and "The Tonight Show" performance.


title: Denzel Curry

text: On February 27, 2014, Curry's brother, Treon "Tree" Johnson, died as a result of complications after being tased by the police in Hialeah, Florida. Officers had responded to an emergency call made by a man claiming that Johnson was beating two dogs with a metal pipe. Officers then employed physical force, pepper spray, and a taser in an attempt to restrain Johnson. He succumbed to his wounds, and he ultimately died after being transported to Jackson Memorial Hospital. His family argued that the incident was a case of police brutality. Curry has spoken about Johnson's death in interviews and in his music.


title: Denzel Curry

text: Curry always expressed his love for art, with many different comic books and anime shows inspiring him to draw.


title: Denzel Curry

text: Until January 2017, Curry lived with XXXTentacion, Ronny J and other members of his C9 collective in Miami in the self-called ULT House. As he himself stated in an interview with Montreality, after he had broke up with his girlfriend, he painted his whole room, and to support him other people living in the ULT House drew all over their walls too. He has since lived in Los Angeles.


title: Denzel Curry

text: In January 2021, Curry found out that he is related to St. Louis rapper Smino through the discovery of a shared uncle.


title: De Beers

text: De Beers Group is an international corporation that specializes in diamond mining, diamond exploitation, diamond retail, diamond trading and industrial diamond manufacturing sectors. The company is active in open-pit, large-scale alluvial and coastal mining. It operates in 35 countries and mining takes place in Botswana, Namibia, South Africa, Canada and Australia.


title: De Beers

text: From its inception in 1888 until the start of the 21st century, De Beers controlled 80% to 85% of rough diamond distribution and was considered a monopoly. Competition has since dismantled the complete monopoly; the De Beers Group now sells approximately 29.5% of the world's rough diamond production by value through its global sightholder and auction sales businesses.


title: De Beers

text: The company was founded in 1888 by British businessman Cecil Rhodes, who was financed by the South African diamond magnate Alfred Beit and the London-based N M Rothschild & Sons bank. In 1926, Ernest Oppenheimer, a German immigrant to Britain and later South Africa who had earlier founded mining company Anglo American with American financier J. P. Morgan, was elected to the board of De Beers. He built and consolidated the company's global monopoly over the diamond industry until his death in 1957. During this time, he was involved in a number of controversies, including price fixing and trust behaviour, and was accused of not releasing industrial diamonds for the U.S. war effort during World War II.


title: De Beers

text: In 2011, Anglo American took control of De Beers after buying the Oppenheimers' family stake of 40% for US$5.1 billion (£3.2 billion) and increasing its stake to 85%, ending the 80-year Oppenheimer control of the company.


title: De Beers

text: The name 'De Beers' was derived from the two Dutch settlers, brothers Diederik Arnoldus de Beer (1825–1878) and Johannes Nicolaas de Beer (1830–1883), who owned a South African farm named "Vooruitzicht" (Dutch for "prospect" or "outlook") near Zandfontein in the Boshof District of Orange Free State. After they discovered diamonds on their land, the increasing demands of the British government forced them to sell their farm on 31 July 1871 to merchant Alfred Johnson Ebden (1820–1908) for £6,600. "Vooruitzicht" would become the site of the Big Hole and the De Beers mine, two successful diamond mines. Their name, which was given to one of the mines, subsequently became associated with the company.


title: De Beers

text: Cecil Rhodes, the founder of the British South Africa Company, got his start by renting water pumps to miners during the diamond rush that started in 1869, when an 83.5 carat diamond called the 'Star of South Africa' was found at Hopetown near the Orange River in South Africa. He invested the profits of this operation into buying up claims of small mining operators, with his operations soon expanding into a separate mining company. He soon secured funding from the Rothschild family, who would finance his business expansion. De Beers Consolidated Mines was formed in 1888 by the merger of the companies of Barney Barnato and Cecil Rhodes, by which time the company was the sole owner of all diamond mining operations in the country. In 1889, Rhodes negotiated a strategic agreement with the London-based Diamond Syndicate, which agreed to purchase a fixed quantity of diamonds at an agreed price, thereby regulating output and maintaining prices. The agreement soon proved to be very successful – for example, during the trade slump of 1891–1892, supply was simply curtailed to maintain the price. Rhodes was concerned about the break-up of the new monopoly, stating to shareholders in 1896 that the company's "only risk is the sudden discovery of new mines, which human nature will work recklessly to the detriment of us all".


title: De Beers

text: The Second Boer War proved to be a challenging time for the company. Kimberley was besieged as soon as war broke out, thereby threatening the company's valuable mines. Rhodes personally moved into the city at the onset of the siege in order to put political pressure on the British government to divert military resources towards relieving the siege rather than more strategic war objectives. Despite being at odds with the military, Rhodes placed the full resources of the company at the disposal of the defenders, manufacturing shells, defences, an armoured train and a gun named "Long Cecil" in the company workshops.


title: De Beers

text: In 1898, diamonds were discovered on farms near Pretoria, Transvaal. One led to the discovery of the Premier Mine. The Premier Mine was registered in 1902 and the Cullinan Diamond, the largest rough diamond ever discovered, was found there in 1905. (The Premier Mine was renamed the Cullinan Mine in 2003). However, its owner refused to join the De Beers cartel. Instead, the mine started selling to a pair of independent dealers named Bernard and Ernest Oppenheimer, thereby weakening the De Beers stronghold.


title: De Beers

text: Francis Oats, who became Chairman of De Beers in 1908, was dismissive of the threats from the Premier Mine and the finds in German South West Africa.


title: De Beers

text: However, production soon equalled all of the De Beers mines combined. Ernest Oppenheimer was appointed the local agent for the powerful London Syndicate, rising to the position of mayor of Kimberley within 10 years. He understood the core principle that underpinned De Beers's success, stating in 1910 that "common sense tells us that the only way to increase the value of diamonds is to make them scarce, that is to reduce production".


title: De Beers

text: During World War I, the Premier mine was finally absorbed into De Beers. When Rhodes died in 1902, De Beers controlled 90% of the world's diamond production. Ernest Oppenheimer took over the chairmanship of the company in 1929, after buying shares and being appointed to the board in 1926. Oppenheimer was very concerned about the discovery of diamonds in 1908 in German South West Africa, fearing that the increased supply would swamp the market and force prices down.


title: De Beers

text: Former CIA chief Admiral Stansfield Turner claimed that De Beers restricted US access to industrial diamonds needed for the country's war effort during World War II.


title: De Beers

text: In May 1955, Ernest Oppenheimer opened the new headquarters which combined the operations of Anglo American and the De Beers group. After Ernest died in November 1957, operation of Anglo and De Beers were passed on to his son, Harry Oppenheimer. Under Harry, the company expanded to several different countries around the globe, including Canada, Australia, Malaysia, Portugal, Zambia, and Tanzania. In South Africa, Harry opposed apartheid, arguing that it hindered economic growth. Despite this, De Beers has been criticized for profiting from the system during the apartheid period. By 1973, Anglo and De Beers accounted for 10 percent of South Africa's gross national product and 30 percent of the country's exports.


title: De Beers

text: Throughout the 1960s and 1970s, De Beers attempted to secretly enter the United States' diamond market, being forced to divest its American assets in 1975 to avoid the risk of violating anti-trust laws. Harry Oppenheimer stepped down as the chairman and director of Anglo-American and De Beers in December 1982.


title: De Beers

text: During the 20th century, De Beers used several methods to leverage its dominant position to influence the international diamond market. First, it attempted to convince independent producers to join its single channel monopoly. When that did not work, it flooded the market with diamonds similar to those of producers who refused to join in, depressing their price and undermining return for the resistant. It also purchased and stockpiled diamonds produced by other manufacturers as well as surplus diamonds in order to control prices by limiting supply. Finally, it bought diamonds when prices fell considerably naturally, to constrict supply and drive their value back up, such as during the Great Depression.


title: De Beers

text: In 2000, the De Beers business model changed because of factors such as the decision by producers in Canada and Australia to distribute diamonds outside the De Beers channel, as well as increasingly negative publicity surrounding blood diamonds, which forced De Beers to protect its image by limiting sales to its own mined products.


title: De Beers

text: The combination of a more fragmented and thus more competitive diamond market, increased transparency, and greater liquidity, caused De Beers's market share of rough diamonds to fall from as high as 90% in the 1980s to 29.5% in 2019.


title: De Beers

text: Seeing these developing trends, the Oppenheimer family announced in November 2011 its intention to sell its entire 40% stake in De Beers to Anglo American plc, thereby increasing Anglo American's ownership of the company to 85% (with the remaining 15% owned by the Government of the Republic of Botswana).


title: De Beers

text: The transaction was worth £3.2 billion (US$5.1 billion) in cash and ended the Oppenheimer dynasty's 80-year ownership of De Beers.


title: De Beers

text: De Beers successfully advertised diamonds to manipulate consumer demand. One of the most effective marketing strategies has been the marketing of diamonds as a symbol of love and commitment. A copywriter working for N. W. Ayer & Son, Frances Gerety (1916–1999), coined the famous advertising slogan, 'A Diamond is Forever', in 1947. In 2000, "Advertising Age" magazine named 'A Diamond is Forever' the best advertising slogan of the 20th century. The slogan may have inspired the James Bond book, film and song title "Diamonds Are Forever".


title: De Beers

text: Other successful campaigns include the 'eternity ring' (meant as a symbol of continuing affection and appreciation), the 'trilogy ring' (meant to represent the past, present, and future of a relationship) and the 'right hand ring' (meant to be bought and worn by women as a symbol of independence).


title: De Beers

text: De Beers ran television advertisements featuring silhouettes of people wearing diamonds, set to the music of 'Palladio' by Karl Jenkins. The campaign, titled "Shadows and Lights" first ran in the first quarter of 1993. The song would later inspire a compilation album, "Diamond Music", released in 1996, which features the 'Palladio' suite. A 2010 commercial for Verizon Wireless parodied the De Beers spots.


title: De Beers

text: In May 2018, De Beers introduced a new brand called "Lightbox" that are made with synthetic diamonds. The synthetic stones start at $200 for a quarter carat to $800 for full carat diamond. The new lab-grown diamond retail for about one-tenth the cost of naturally occurring diamonds. The new brand began selling in September 2018 and are produced in Gresham, Oregon, a $94 million facility using the region's cheap electricity, which opened in 2018 with the capacity for 500,000 rough carats of diamonds per year.


title: De Beers

text: Mining in Botswana takes place through the mining company Debswana, a 50–50 joint venture with the Government of the Republic of Botswana. It operates four mines – Jwaneng, Orapa, Letlhakane and Damtshaa, though Damtshaa was put on care and maintenance in 2015.


title: De Beers

text: In Namibia, mining is carried out through Namdeb Holdings, a 50–50 joint venture with the Government of the Republic of Namibia. Namdeb Holdings is made up of Debmarine Namibia (covering offshore mining) and Namdeb Diamond Corporation (land-based coastal mining). For offshore mining, motor vessels are used, including the sixth and latest, the N$2.3 billion SS Nujoma, the world's most advanced diamond exploration and sampling vessel, which began full operations in June 2017.


title: De Beers

text: De Beers Consolidated Mines is responsible for the De Beers mining in South Africa. It is 74% owned by De Beers and 26% by a broad-based black economic empowerment partner, Ponahalo Investments. There are two mines – Venetia and Voorspoed.


title: De Beers

text: In 2008, De Beers began production at the Snap Lake mine in the Northwest Territories, Canada; this was the first De Beers mine outside Africa and was Canada's first completely underground diamond mine. However, production was suspended when the mine was put on care and maintenance in 2015. De Beers opened the Victor mine in Ontario, Canada, the same year, a day after Snap Lake. This was followed by the opening of the company's third mine in Canada, Gahcho Kue, in September 2016.


title: De Beers

text: Trading of rough diamonds takes place through two channels – De Beers Global Sightholder Sales (GSS) and De Beers Auction Sales. GSS sells about 90% of De Beers's rough diamonds, by value, and features wholly owned and joint venture operations in South Africa (De Beers Sightholder Sales South Africa), Botswana (DTCB), and Namibia (NDTC). They sort, value and sell 33% (2013) of the world's rough diamonds by value.


title: De Beers

text: There are two main types of customer for rough diamonds – Sightholders and Accredited Buyers. Sightholders have a term contract. Accredited Buyers (a customer type introduced in 2014–15) have a more ad hoc arrangement. De Beers also sells about 10% of its rough diamonds through online auction sales. The company pioneered the approach in 2008 when it broke with 44 years of direct sales to hold the diamond industry's first online international auction sale. It is now the world's leader in this kind of auction sale.


title: De Beers

text: De Beers employs more than 30,000 people around the globe on five continents, with more than 17,000 employees in Africa. Almost 8,000 people are employed in Botswana, around 6,200 in South Africa, nearly 2,900 in Namibia, some 1,260 in Canada and about 320 in exploration.


title: De Beers

text: In February 2020, De Beers reported its worst set of earnings since the company was bought by miner Anglo American in 2012.


title: De Beers

text: On 4 November 2011, Anglo American plc and CHL Holdings announced their agreement for Anglo American to acquire an incremental interest in De Beers, increasing Anglo American's 45% shareholding in the world's leading diamond company to 85%. De Beers plc was originally incorporated as De Beers Société Anonyme in 2000 in Luxembourg. Following the closure of this office, the company was reclassified as De Beers plc in 2017, with its head office now in Jersey. It is made up of two shareholdings: Anglo American plc has an 85% shareholding and the Government of the Republic of Botswana owns 15% directly. De Beers plc is the holding company of The De Beers Group of Companies. It is involved in many parts of the diamond value chain, from mining to sales, and is made up of a series of joint ventures and wholly owned operations.


title: De Beers

text: The wholly owned operations are in southern Africa and Canada. Also wholly owned are Forevermark, De Beers Jewellers, the International Institute of Diamond Valuation, De Beers Ventures, the International Institute of Diamond Grading & Research and Element Six (Umicore has a 40% stake in Element Six's abrasives division).


title: De Beers

text: Forevermark was launched in 2008 as one of the two diamond brands from The De Beers Group of Companies. According to the company website, "Each Forevermark diamond is inscribed with a promise: that it is beautiful, rare and responsibly sourced." Forevermark diamonds are inscribed with an icon and unique identification number, albeit invisibly to the naked eye: the Forevermark inscription is th of a micron deep. This inscription helps distinguish Forevermark diamonds from other natural diamonds though, similarly to when distinguishing natural diamonds from synthetic diamonds, it requires specialist detection equipment to view. The inscription also helps maintain scarcity: the Forevermark website boasts that only a tiny percentage of diamonds qualify for the Forevermark brand.


title: De Beers

text: De Beers Diamond Jewellers (DBDJ) was established in 2001 as a 50:50 joint venture between The De Beers Group of Companies and LVMH, the French luxury goods company. The first De Beers boutique opened in 2002 on London's Old Bond Street as the brand's flagship store. Since then, stores have opened in various cities around the world. In March 2017, The De Beers Group of Companies acquired LVMH's 50% shareholding in DBDJ and new name De Beers Jewellers was unveiled.


title: De Beers

text: De Beers Ventures was established by De Beers Group in June 2017 to consider minority stake investments in start-ups and growth companies that could be of benefit to De Beers Group or the broader diamond sector.


title: De Beers

text: The International Institute of Diamond Grading & Research (IIDGR) was set up by De Beers in 2008, with the aim of providing a range of services and equipment in the field of diamond verification. It is based in London, Antwerp and, from 2015, in Surat, India. The IIDGR works only on diamonds that meet the requirements of the United Nations' World Diamond Council Kimberley Process.


title: De Beers

text: In 1999, a campaign by Global Witness to highlight the role of diamonds in international conflicts led to a review by the United Nations. The initial focus of the UN's investigation was on Jonas Savimbi's UNITA movement in Angola, which was found to have bartered uncut diamonds for weaponry despite international economic and diplomatic sanctions being in effect through United Nations Security Council Resolution 1173.


title: De Beers

text: In 1999, De Beers Group stopped all outside buying of diamonds in order to guarantee the conflict-free status of their diamonds effective from 26 March 2000.


title: De Beers

text: In December 2000, following the recommendations of the Fowler Report, the UN adopted the landmark General Assembly Resolution A/RES/55/56 supporting the creation of an international certification scheme for rough diamonds. By November 2002, negotiations between governments, the international diamond industry, led by De Beers, and civil society organisations resulted in the creation of the Kimberley Process Certification Scheme (KPCS), which sets out the requirements for controlling rough diamond production and trade and became effective in 2003.


title: De Beers

text: De Beers states that 100% of the diamonds it now sells are conflict-free and that all De Beers diamonds are purchased in compliance with national law, the Kimberley Process Certification Scheme and its own Diamond Best Practice Principles. The Kimberley process has helped restore the reputation of the industry, as well as eliminating sources of excess supply.


title: De Beers

text: In 2018, De Beers used blockchain technology to successfully track 100 high-value diamonds. The diamonds were tracked through the manufacturing process from the mine to the retailer in order to ensure their quality and conflict-free status.


title: De Beers

text: In 2019, they launched their own end-to-end traceability platform called Tracr to enable all diamonds to be identified and traced as they move from the mine to the store. Signet and the Russian-based Alrosa are using the technology.


title: De Beers

text: In August 2017, De Beers partnered with the Stanford Graduate School of Business to accelerate business ventures to market in Botswana, Namibia, and South Africa. As part of two programs, the partnership is set to help teach early entrepreneurs how to commercialize their business ideas. The partnership is a three-year, $3 million deal.


title: De Beers

text: In September 2017, De Beers partnered with UN Women to help the advancement of women within the company and the countries it operates in. In 2018, the two entities launched a program to support 500 women micro-entrepreneurs in Blouberg and Musina communities, near De Beers's Venetia diamond mine.


title: De Beers

text: In May 2018, De Beers's group company Element Six launched a lab-grown diamond brand to sell jewelry directly to consumers.


title: De Beers

text: The International Institute of Diamond Valuation (IIDV) was launched by De Beers Group in March 2016. Operating in partnership with diamond jewellery retailers, it provided a reselling service for all diamonds, regardless of value. In April 2019, De Beers closed its IIDV division.


title: De Beers

text: During World War II, Ernest Oppenheimer attempted to negotiate a way around the Sherman Antitrust Act by proposing that De Beers register a US branch of the Diamond Syndicate Incorporated. In this way, his company could provide the US with the industrial diamonds it desperately sought for the war effort in return for immunity from prosecution after the war; however his proposal was rejected by the US Justice Department when it was discovered that De Beers had no intention of stockpiling any industrial diamonds in the US. In 1945, the Justice Department finally filed an antitrust case against De Beers, but the case was dismissed as the company had no presence on US soil.


title: De Beers

text: In Botswana, a long dispute has existed between the interests of the mining company, De Beers, and the San (Bushman) tribe. The San have been facing threats of forcible relocation since 1980s, when the diamond resources were discovered. A campaign was fought in an attempt to bring an end to what the indigenous rights organisation, Survival International, considers to be a genocide of a tribe that has been living in those lands for tens of thousands of years. Several international fashion models, including Iman, Lily Cole and Erin O'Connor, who were previously involved with advertising for the companies' diamonds, supported the campaign. De Beers sold its mine in Botswana to Gem Diamonds in 2007.


title: De Beers

text: In 2004, De Beers pled guilty and paid a US$10 million fine to the United States Department of Justice to settle a 1994 charge that De Beers had colluded with General Electric to fix the price of industrial diamonds. In 2008, De Beers agreed to pay US$295 million class-action settlement after accusations of price fixing. The company appealed the decision but ended up paying the settlement in 2013.


title: De Beers

text: In February 2006, De Beers entered into legally binding commitments with the European Commission to cease purchasing rough diamonds from Russian mining company Alrosa as of the end of 2008 in order to ensure competition between the two companies.


title: De Beers

text: In 2014, the Leverhulme Centre for the Study of Value, based at the University of Manchester, published a report authored by Sarah Bracking and Khadija Sharife, identifying over US$3.3 billion in price fixing within the South African rough diamond trade from 2004 to 2012, leading to an estimated deficit in tax paid of ZAR 1 billion per year. The report found significant evidence of profit shifting through volume and value manipulation. Sharife simultaneously published an article disclosing the political system that cultivated revenue leakage, including the donation of De Beers staff to the State Diamond Trader (SDT). The report, like the article, utilised aggregated data produced by the Kimberley Process (KP) certificates of import-exports, relying on figures listed by the diamond companies themselves, in which De Beers was the dominant player. The South African Department of Mineral Resources (DMR) disclosed that De Beers did not authorise them to publish figures involving values, sales, pricing and other data, preventing transparency of the industry.