Contraction Induced Muscle Injury: Towards Personalized Training and Recovery Programs

Abstract

Skeletal muscles can be injured by their own contractions. Such contraction-induced injury, often accompanied by delayed onset of muscle soreness, is a leading cause of the loss of mobility in the rapidly increasing population of elderly people. Unlike other types of muscle injuries which hurt almost exclusively those who are subjected to intensive exercise such as professional athletes and soldiers in training, contraction induced injury is a phenomenon which may be experienced by people of all ages while performing a variety of daily-life activities. Subjects that experience contraction induced injury report on soreness that usually increases in intensity in the first 24 h after the activity, peaks from 24 to 72 h, and then subsides and disappears in a few days. Despite their clinical importance and wide influence, there are almost no studies, clinical, experimental or computational, that quantitatively relate between the extent of contraction induced injury and activity factors, such as number of repetitions, their frequency and magnitude. The lack of such quantitative information is even more emphasized by the fact that contraction induced injury can be used, if moderate and controlled, to improve muscle performance in the long term. Thus, if properly understood and carefully implemented, contraction induced injury can be used for the purpose of personalized training and recovery programs. In this paper, we review experimental, clinical, and theoretical works, attempting towards drawing a more quantitative description of contraction induced injury and related phenomena.

Insights into the molecular etiology of exercise-induced inflammation: opportunities for optimizing performance

“…This theory was further supported by marked sarcomeric distortions (e.g., Z-line streaming) identified by electron microscopy following EIMD in both human and animal studies12,23,24 or infiltration of extracellular dyes into the muscle in animal studies 16,25. Damage of muscle fiber membrane also causes influx of extracellular substances (e.g., albumin and fibronectin) 12,26,27. Increased membrane permeability has been linked to the stimulation of sodium and calcium channels in response to repetitive stretching of muscle fibers by lengthening contractions 28,29.…”

“…This notion was further supported by the indirect evidence of increased concentration of muscle proteins into the circulation in response to EIMD, suggesting a potential leakage of intracellular content due to damage of muscle fiber membrane 12,21,22. This theory was further supported by marked sarcomeric distortions (e.g., Z-line streaming) identified by electron microscopy following EIMD in both human and animal studies12,23,24 or infiltration of extracellular dyes into the muscle in animal studies 16,25. Damage of muscle fiber membrane also causes influx of extracellular substances (e.g., albumin and fibronectin) 12,26,27.…”

“…DOMS and strength loss during EIMD were originally attributed to subcellular disruption of skeletal muscle fibers 10,12. This notion was further supported by the indirect evidence of increased concentration of muscle proteins into the circulation in response to EIMD, suggesting a potential leakage of intracellular content due to damage of muscle fiber membrane 12,21,22.…”

“…Eccentric (lengthening) work, either in their isolated form on an isokinetic dynamometer or as a part of the stretch-shortening cycle during downhill running, is used experimentally to study EIMD. In fact, eccentric EIMD is thought to be the basis for the increase of skeletal muscle mass (hypertrophy) seen with exercise training, especially resistance exercise training, suggesting that muscle micro-trauma induced by mechanical stress of acute exercise is a prerequisite for its subsequent growth during the adaptation phase 11,12. Moreover, Givli12 suggested that EIMD may also be utilized to develop safer and more effective training and recovery protocols based on a personalized approach.…”

“…Increased membrane permeability has been linked to the stimulation of sodium and calcium channels in response to repetitive stretching of muscle fibers by lengthening contractions 28,29. Nevertheless, a large variation exists in the manifestations of the magnitude of EIMD induced by eccentric exercise protocols ranging from extensive local or systemic inflammatory responses and myofiber trauma7,12,30 to less pronounced injury in humans31 probably due to large variations in muscles tested as well as exercise protocols used. Moreover, protocols using electrical stimulation on animals to simulate eccentric contractions, although useful to study molecular mechanisms underlying EIMD, may not be physiologically relevant to that produced by humans 32.…”