Aerobic exercise (also known as endurance activities, cardio or cardio-respiratory exercise) is physical exercise of low to high intensity that depends primarily on the aerobic energy-generating process. "Aerobic" is defined as "relating to, involving, or requiring oxygen", and refers to the use of oxygen to meet energy demands during exercise via aerobic metabolism adequately. Aerobic exercise is performed by repeating sequences of light-to-moderate intensity activities for extended periods of time.  Examples of cardiovascular or aerobic exercise are medium- to long-distance running or jogging, swimming, cycling, stair climbing and walking.

For reducing the risk of health issues, 2.5 hours of moderate-intensity aerobic exercise per week is recommended. At the same time, even doing an hour and a quarter (11 minutes/day) of exercise can reduce the risk of early death, cardiovascular disease, stroke, and cancer.

Aerobic exercise may be better referred to as "solely aerobic", as it is designed to be low-intensity enough that all carbohydrates are aerobically turned into energy via mitochondrial ATP production. Mitochondria are organelles that rely on oxygen for the metabolism of carbs, proteins, and fats. Aerobic exercise causes a remodeling of mitochondrial cells within the tissues of the liver and heart.

History 

Archibald Hill, a British physiologist, introduced the concepts of maximal oxygen uptake and oxygen debt in 1922. German physician Otto Meyerhof and Hill shared the 1922 Nobel Prize in Physiology or Medicine for their independent work related to muscle energy metabolism. Building on this work, scientists began measuring oxygen consumption during exercise. Henry Taylor at the University of Minnesota and Swedish scientists Per-Olof Åstrand and Bengt Saltin made notable contributions in the 1950s and 60s. Contributions were also made by the Harvard Fatigue Laboratory, Copenhagen Muscle Research Centre as well as various German universities.

After World War II, health-oriented recreational activities such as jogging became popular. The Royal Canadian Air Force Exercise Plans, developed by Dr. Bill Orban and published in 1961, helped to launch modern fitness culture.

Physical therapists Col. Pauline Potts and Dr. Kenneth H. Cooper, both of the United States Air Force, advocated the concept of aerobic exercise. In the 1960s, Cooper started research into preventive medicine. He conducted the first extensive research on aerobic exercise on over 5,000 U.S. Air Force personnel after becoming intrigued by the belief that exercise can preserve one's health. In 1966 he coined the term "aerobics". Two years later, in 1968, he published a book of the same name. In 1970, he created the Cooper Institute for non-profit research and education devoted to preventive medicine. He published a mass-market version of his book The New Aerobics in 1979. Cooper encouraged millions into becoming active and is now known as the "father of aerobics". Cooper's book inspired Jacki Sorensen to create aerobic dancing exercise routines, which grew in popularity in the 1970s in the U.S., and at the same time, Judi Missett developed and expanded Jazzercise.

In the 1970s, there was a running boom. It was inspired by the Olympics, the New-York marathon and the advent of cushioned shoes.

Aerobics at home became popular worldwide after the release of Jane Fonda's Workout exercise video in 1982. Step aerobics was popular in the 1990s, driven by a step product and program from Reebok shoes.

Definition 

Aerobic exercise comprises innumerable forms. In general, it is performed at a moderate level of intensity over a relatively long period of time. For example, running a long distance at a moderate pace is an aerobic exercise, but sprinting is not. Playing singles tennis, with near-continuous motion, is generally considered aerobic activity, while activities with brief bursts of energetic movement within longer periods of casual movement may not be aerobic. Some sports are thus inherently "aerobic", while other aerobic exercises, such as fartlek training or aerobic dance classes, are designed specifically to improve aerobic capacity and fitness. It is most common for aerobic exercises to involve the leg muscles, primarily or exclusively. There are some exceptions. For example, rowing to distances of 2,000 meters or more is an aerobic sport that exercises several major muscle groups, including those of the legs, abdominals, chest, and arms.

Examples

Moderate activities
 Swimming
 Dancing
 Hiking on flat ground
 Bicycling at less than 
 Moderate walking (about )
 Downhill skiing
 Tennis (doubles)
 Softball
 Gardening
 Light yard work
Jogging

Vigorous activities

 Brisk walking (about )
 Bicycling at more than 
 Hiking uphill
 Cross-country skiing
 Stair climbing
 Soccer
 Jogging
 Jumping rope
 Tennis (singles)
 Basketball
 Heavy yard work

Versus anaerobic exercise 
Aerobic exercise and fitness can be contrasted with anaerobic exercise, of which strength training and short-distance running are the most salient examples. The two types of exercise differ by the duration and intensity of muscular contractions involved, as well as by how energy is generated within the muscle.

New research on the endocrine functions of contracting muscles has shown that both aerobic and anaerobic exercise promote the secretion of myokines, with attendant benefits including growth of new tissue, tissue repair, and various anti-inflammatory functions, which in turn reduce the risk of developing various inflammatory diseases. Myokine secretion in turn is dependent on the amount of muscle contracted, and the duration and intensity of contraction. As such, both types of exercise produce endocrine benefits.

In almost all conditions, anaerobic exercise is accompanied by aerobic (in the presence of oxygen) exercises because the less efficient anaerobic metabolism must supplement the aerobic system due to energy demands that exceed the aerobic system's capacity. During anaerobic exercise, the body must generate energy through other processes than aerobic metabolism, including glycolysis paired with lactic acid fermentation, and the phosphocreatine system to generate energy in the form of ATP. Common kettlebell exercises combine aerobic and anaerobic aspects. Allowing 24 hours of recovery between aerobic and strength exercise leads to greater fitness.

Fuel usage 
Depending on the intensity of exercise, the body preferentially utilizes certain fuel forms to meet energy demands. The two main fuel sources for aerobic exercise in the body include fat (in the form of adipose tissue) and glycogen. At lower intensity aerobic exercise, the body preferentially uses fat as its main fuel source for cellular respiration, however as intensity increases the body preferentially uses glycogen stored in the muscles and liver or other carbohydrates, as it is a quicker source of energy. Aerobic exercise is not a very efficient way to burn fat in comparison to other forms of exercise, as in order to preferentially burn fat one should exercise at lower intensities, which decreases the overall amount of calories burned per unit of time.

Health effects
Among the possible health benefits of regular aerobic exercise are:

May improve mood
Strengthens and enlarges the heart muscle, to improve its pumping efficiency and reduce the resting heart rate, known as aerobic conditioning
May improve circulation efficiency and reduce blood pressure
May help maintain independence in later life
Increases the total number of red blood cells in the body, facilitating transport of oxygen
Improves mental health, including reducing stress and lowering the incidence of depression, as well as increased cognitive capacity.
Slightly reduced depression may also be observed, especially if aerobic exercises are used as additional treatment for patients with a hematological malignancy 
Reduces the risk for diabetes (One meta-analysis has shown, from multiple conducted studies, that aerobic exercise does help lower Hb A1Clevels for type 2 diabetics.)
Moderates the risk of death due to cardiovascular problems
Promotes weight loss
Reduces the risk of osteoporosis
 May improve episodic memory

Risks and disadvantages 
Some drawbacks of aerobic exercise include:

 Overuse injuries of the musculoskeletal system because of repetitive exercise, with young athletes (under the age of 19) particularly at risk
 Overtraining syndrome may lead to persistent dysfunction of a number of body systems 
 High volumes of training with insufficient calorie intake puts athletes—particularly female ones—at risk for RED-S
 Aerobic exercise may not be as efficient as other exercise methods. For example, High-intensity interval training (HIIT) has been shown to provide similar benefits in a fraction of the time spent exercising per week.

Both the health benefits and the performance benefits, or "training effect", require that the duration and the frequency of exercise both exceed a certain minimum. Most authorities suggest at least twenty minutes performed at least three times per week.

Commercialization
Aerobic exercise has long been a popular approach to achieving weight loss and physical fitness, often taking a commercial form.

 In the 1970s, Judi Sheppard Missett helped create the market for commercial aerobics with her Jazzercise program, at the same time as Jacki Sorensen was expanding her system of aerobic dancing.
 In the 1980s, Richard Simmons hosted an aerobic exercise show on television, and followed Jane Fonda's lead by releasing a series of exercise videos.
 In the 1990s, Billy Blanks's Tae Bo helped popularize cardio-boxing workouts that incorporated martial arts movements. Reebok shoes popularized step aerobics with their Reebok Step device and training program.

See also 
 Aerobics
 Endurance training
 Exercise physiology
 Neurobiological effects of physical exercise
 Music and aerobic exercise performance

References

Further reading

External links 
 

 
Exercise physiology
유산소 운동(有氧運動, )은 운동시 발생하는 에너지 소비가 적절하고 충분한 산소의 공급을 조건으로 시행되는 신체의 지속적인 운동 부하를 의미한다. 따라서 유산소 운동의 주요한 요건은 숨이 가쁘지 않는 상태에서 신체가 부하를 받게되는 균형있는 호흡(유기호흡)을 통해 얻는 운동방식이다. 이러한 조건하에 보통 30분 이상 지속 가능한 운동을 가리킬수있으나 30분을 전후할 수 있는 유연성을 제공하는 운동을 의미할수도 있다. 유산소 운동은 체계적이고 세밀한 계획하에서 무산소 운동보다 더 탄수화물 뿐만 아니라 지방도 에너지원으로 사용할 수 있는데 효과적일수있다.

따라서 이러한 유산소 운동은 일반적으로 주요하게 호흡기 계통의 호흡 조절을 통해서 심신을 효과적으로 다루도록 의도한다.

고안된 계기 
1968년 미국의 심장병 전문의인 케네스 쿠퍼(Kenneth Cooper)가 심장병 치료를 위한 운동 요법으로 고안하였는데, 미국항공우주국에서 우주비행사의 신체적성 프로그램으로 이용되어 큰 호응을 얻은 뒤부터 민간단체의 예방의학적 차원에서 대중운동으로 실시하게 되었다. 국내에는 1974년 2월 YMCA(Young Men's Christian Association:기독교청년회) 초청으로 내한한 쿠퍼 박사가 워크숍을 통해 소개하면서 보급되었다. 현재 많은 운동 종목에서 심폐 지구력 강화 프로그램에 활용된다.

이점 
 스트레스를 감소시킨다.
 지방산을 주된 에너지로 사용할 수 있다.
 꾸준히 하면 안정시심박수와 혈압을 조절하는데 도움을 준다.
 근지구력이 향상된다.
 체지방률을 낮춰준다.
 심신을 안정시킨다.
 심신을 활발하게 하는 원동력이 된다.
 혈액순환이 개선된다.
 뇌의 노화를 막아준다. 뇌의 크기가 오히려 커진다.
 집중력이 높아진다.

종류 
유산소 운동은 종류에 구애받지 않는다. 균형있게 잘짜여진 호흡조건하에서라면 즐기는 모든 활동이 유산소 운동에 포함될수있다. 다음과 같은 것이 있다.
 걷기
 달리기
 자전거타기
 수영
 줄넘기
 에어로빅댄스
 등산
 배드민턴
 테니스
 탁구
 축구
 농구
 조깅
 경보
 크로스컨트리
 스키
 수상스키
 댄스
 요가
 간화태극권
 코어근육운동
등

운동 강도 
유산소 운동의 강도는 목표 심박수에 맞춰 해야 효과가 극대화 되고, 부상의 위험도 적다.
우선 자신의 최대 심박수(1분 당 심박수)를 측정한다.
 저강도 구간 - 최대 심박수의 60% 이하인 구간 또는 최대산소섭취량(VO2max)의 45~60%이하의 구간으로 초보자에게 적합하며 때로는 숙련자가  호흡의 균형과 운동의 효율성을 전제로 최소한의 에너지 소비를 필요로하는 컨디션을 고려해야하는 상황에서 이를 사용할 수 있다.
 중강도 구간 - 최대 심박수를 60~70%까지 상승시킨 구간으로 중급자에게 적합하다.
 중/고강도 구간 - 운동을 오래 지속할 수 없는 수준의 강도로 무산소 운동 바로 직전이라 할 수 있다. 숙련자에게 적합하다.
 고강도 구간 - 운동의 지속 시간이 10초 이내인 수준의 강도이다. 최대 심박수의 85% 이상(무산소 운동의 강도)을 수행하면, 에너지가 소멸되는 속도보다 젖산이 근육에 쌓이는 속도가 더 빨라서 피로를 느끼게 된다.

운동 방법 
처음부터 너무 강도 높은 운동을 하면 심장을 포함한 몸에 무리가 온다. 또한 격일 운동과 매일 운동에 의한 근 비대 효과는 거의 동일한 수준을 유지하는데 유의미하다는 연구보고가 있다는 점을 고려해서 따라서 시작 처음 몇 주이상 동안은 회 당 유산소 운동 시간을 짧게 정하여 실시할 수 있다. 일주일에 2~3회, 1회 20~30분 정도로 시작하는 전략을 고려해볼 수 있다. 그리고 점차 횟수와 시간을 늘린다.

운동의 시작과 끝엔 반드시 준비운동과 정리운동을 하고, 적절한 타이밍에 수분을 충분히 섭취한다. 운동 도중에 몸에 통증이 느껴지거나 호흡이 곤란하면 운동을 즉시 멈춘다.

운동은 꾸준히, 규칙적으로 하는 것이 좋다. 따라서 갑자기 강도를 높이거나 며칠씩 쉰 후 몰아서 하는 것은 좋지 않다. 무엇보다 일상 생활 속에 포함된 운동이 장기적으로 봤을 때 가장 좋다. 많은 생화학등의 관련 과학자들은 운동 특히 유산소운동이 에너지대사의 소비효율과 신진대사의 안정궤도를 회복하거나 유지하는데 주요한 원리로 제시하고 있으며 현실적으로도 충분한 휴식 그리고 적절한 에너지 섭취와 동등하게 그 필요성이 여겨지고 있다. 또한 유산소운동의 특성상 호흡을 기준으로 움직임의 속도를 조절하는 과정은 자신의 체중을 도구로 인식하고 이를 사용하는데 효율적이다.

같이 보기 
 호흡
 유기호흡
 젖산 발효(:en:Lactic acid fermentation)
 TCA 회로
 피지컬 피트니스
 인터벌 트레이닝
 무산소 운동
 운동생리학(:en:Exercise physiology)
 EPOC(:en:Excess post-exercise oxygen consumption)
 요요 현상
 대사 증후군
 등척성 운동

참고

(기초간호자연과학회지: 제13권 제1호 2011 ISSN: 1229-6155 J Korean Biol Nurs Sci 2011; 13(1): 1-7 www.bionursing.or.kr 저강도 격일 운동과 매일 운동이 쥐 뒷다리근에 미치는 근 비대 효과 비교 최명애1·고종진2·곽현경3·백지현4·정진영3·송연정4·안경주6 1 서울대학교 간호대학 교수, 2
국군함평병원 간호사, 3서울대병원 간호사, 4서울아산병원 간호사, 5서울대학교 간호대학 학부생, 6청주대학교 간호학과 조교수)https://pdfs.semanticscholar.org/ea5e/902ebc5d0179d490a2de503e18ef0f23ef8d.pdf