Physical exercise, inflammatory process and adaptive condition: an overview <s> OveRlOAD AND ADAPTIve CONDITION <s> Overtraining syndrome (OTS) is a condition wherein an athlete is training excessively, yet performance deteriorates. This is usually accompanied by mood/behavior changes and a variety of biochemical and physiological alterations. Presently, there is no global hypothesis to account for OTS. The present paper will attempt to provide a unifying paradigm that will integrate previous research under the rubric of the cytokine hypothesis of overtraining. It is argued that high volume/intensity training, with insufficient rest, will produce muscle and/or skeletal and/or joint trauma. Circulating monocytes are then activated by injury-related cytokines, and in turn produce large quantities of proinflammatory IL-1beta, and/or IL-6, and/or TNF-alpha, producing systemic inflammation. Elevated circulating cytokines then co-ordinate the whole-body response by: a) communicating with the CNS and inducing a set of behaviors referred to as "sickness" behavior, which involves mood and behavior changes that support resolution of systemic inflammation: b) adjusting liver function, to support the up-regulation of gluconeogenesis, as well as de novo synthesis of acute phase proteins, and a concomitant hypercatabolic state; and c) impacting on immune function. Theoretically, OTS is viewed as the third stage of Selye's general adaptation syndrome, with the focus being on recovery/survival, and not adaptation, and is deemed to be "protective," occurring in response to excessive physical/physiological stress. Recommendations are made for potential markers of OTS, based on a systemic inflammatory condition. <s> BIB001 </s> Physical exercise, inflammatory process and adaptive condition: an overview <s> OveRlOAD AND ADAPTIve CONDITION <s> An athlete who trains intensely, yet consistently underperforms, ::: is considered to be suffering from overtraining syndrome ::: (OTS). OTS is a complex state that involves a large variety ::: of signs and symptoms. Symptoms include changes in mood ::: or behaviour, decreases or increases in concentration of different ::: blood molecules, and alterations in immune function. Although ::: several hypotheses have been proposed, each only explains a selective ::: aspect of OTS. Presently, the sole agreement is that OTS ::: is associated with excessive training and insufficient rest and ::: recovery. The hypothesis proposed in this paper suggests that ::: excessive training/competing causes repetitive tissue trauma, either ::: to muscle and/or connective tissue and/or to bony structures, ::: and that this results in chronic inflammation. It is further ::: proposed that traumatized tissue synthesizes a group of inflammatory ::: molecules, cytokines. Cytokines have been shown to coordinate ::: the different systems of the body to promote recovery. ::: Suggestions are made to detect, prevent, and rehabilitate the ::: overtrained athlete. <s> BIB002 </s> Physical exercise, inflammatory process and adaptive condition: an overview <s> OveRlOAD AND ADAPTIve CONDITION <s> Physical activity relies on muscular force. In adult skeletal muscle, force results from the contraction of postmitotic, multinucleated myofibres of different contractile and metabolic properties. Myofibres can adapt to (patho-)physiological conditions of altered functional demand by radial growth, longitudinal growth, and regulation of fibre type functional gene modules. The adaptation’s specificity depends on the distinct molecular and cellular events triggered by unique combinations of conditional cues. In order to derive effective and tailored exercise prescriptions, it must be determined (1) which mechano-biological condition leads to what molecular/cellular response, and (2) how this molecular/cellular response relates to the structural, contractile, and metabolic adaptation. It follows that a thorough mechano-biological description of the loading condition is imperative. Unfortunately, the definition of (resistance) exercise conditions in the past and present literature is insufficient. It is classically limited to load magnitude, number of repetitions and sets, rest in-between sets, number of interventions/week, and training period. In this review, we show why the current description is insufficient, and identify new determinants of quantitative and/or qualitative effects on skeletal muscle with respect to resistance exercise in healthy, adult humans. These new mandatory determinants comprise the fractional and temporal distribution of the contraction modes per repetition, duration of one repetition, rest in-between repetitions, time under tension, muscular failure, range of motion, recovery time, and anatomical definition. We strongly recommend to standardise the design and description of all future resistance exercise investigations by using the herein proposed set of 13 mechano-biological determinants (classical and new ones). <s> BIB003 </s> Physical exercise, inflammatory process and adaptive condition: an overview <s> OveRlOAD AND ADAPTIve CONDITION <s> Skeletal muscle is comprised of heterogeneous muscle fibers that differ in their physiological and metabolic parameters. It is this diversity that enables different muscle groups to provide a variety of functional properties. In response to environmental demands, skeletal muscle remodels by activating signaling pathways to reprogram gene expression to sustain muscle performance. Studies have been performed using exercise, electrical stimulation, transgenic animal models, disease states, and microgravity to show genetic alterations and transitions of muscle fibers in response to functional demands. Various components of calcium-dependent signaling pathways and multiple transcription factors, coactivators and corepressors have been shown to be involved in skeletal muscle remodeling. Understanding the mechanisms involved in modulating skeletal muscle phenotypes can potentiate the development of new therapeutic measures to ameliorate muscular diseases. <s> BIB004 </s> Physical exercise, inflammatory process and adaptive condition: an overview <s> OveRlOAD AND ADAPTIve CONDITION <s> The current schedule of the Brazilian Soccer Championship may not give players enough recovery time between games. This could increase the chances of muscle damage and impaired performance. We hypothesized that plasma creatine kinase (CK) activity could be a reliable indirect marker of muscle overload in soccer players, so we sought to identify the reference values for upper limits of CK activity during a real-life elite competition. This study analyzed changes in plasma CK activity in 128 professional soccer players at different times during the Brazilian Championship. The upper limits of the 97.5th and 90th percentiles determined for CK activity were 1.338U/L and 975U/L, respectively, markedly higher than values previously reported in the literature. We also evaluated a team monthly throughout the Championship. The upper limit of the 90th percentile, 975U/L, was taken as the decision limit. Six players showing plasma CK values higher than this were asked to decrease their training for 1 week. These players presented lower CK values afterwards. Only one player with a CK value higher than the decision limit (1800U/L 1 day before a game) played on the field and was unfortunately injured during the game. The CK activity in all the other players showed a significant decrease over the course of the Championship, and the values became more homogeneous at the end. The results presented here suggest that plasma CK upper limit values can be used as a practical alternative for early detection of muscle overload in competing soccer players. <s> BIB005
The overload principle is one of the training principles required to improve physical performance. It is assumed that progressive overloads should be applied during training sessions in order to cause a disturbance of cell homeostasis and the resulting response to this stress. Overloads can be manipulated through the following variables: load, duration, interval between stimuli, muscle action, movement execution speed, frequency of exercises per week, number of exercises per session, range of motion and the combination of exercises in the exercise session BIB003 . The application of overload causes tissue traumas of several degrees in skeletal muscle tissue, connective and bone tissue. These traumas are considered temporary and repairable damage, because they result in an acute inflammatory response triggered, among others, by neutrophils and macrophages BIB001 , whose function is to clean, repair and develop tissues previously injured BIB001 . Especially in relation to skeletal muscle tissue, these traumas are dependent on effort intensity and include disruption of the extracellular matrix, basal lamina and sarcolemma. They may result in the release of intracellular proteins into the bloodstream such as myoglobin, lactate dehydrogenase, aspartate aminotransferase and creatine kinase (CK) BIB005 . It can also cause damage to the contractile material and to cytoskeletal proteins, as well as a disruption in the myofibrillar structure, rupture, enlargement or extension of the Z line with subsequent impairment of the anchorage of thin filaments and connection of adjacent fibers BIB005 . When the resting time required for recovery from the acute effects of physical exercise is respected, there is a positive adaptation of the skeletal muscle tissue and adjacent structures for a morphological and metabolic remodeling of myofibrils BIB002 . That is, the adaptive process involves the activation of intracellular signaling pathways and subsequent gene activation, which may result in changes in the muscle mass, in contractile properties and metabolic responses BIB004 . This signaling is dependent on the specificity of the exercises used, which reflects in increased performance of several physical capacities 2 .