Exercise, Muscle Damage and Fatigue*

Abstract

Fatigue as a functional sign and muscle damage as a structural sign can be observed after prolonged exercise like marathon running or after strenuous exercise, especially with the involvement of eccentric contractions. For fatigue due to prolonged exercise, hypoxic conditions and the formation of free oxygen radicals seem to be of aetiological importance, resulting in an elevated lysosomal activity. Eccentric exercise of high intensity rather results in a mechanical stress to the fibres. Although these different mechanisms can be discerned experimentally, both result in similar impairments of muscle function. A good training status may attenuate the clinical signs of fatigue and muscle damage. The symptoms and events occurring during delayed onset of muscle soreness (DOMS) can be explained by a cascade of events following structural damage to muscle proteins.

Effects of Eccentric Exercise on Cycling Efficiency

“…Eccentric exercise induces delayed-onset muscle soreness, muscle fibre disruption, and functional impairment, as shown by the concomitant decrease in maximal voluntary contraction (MVC) and maximal power output (Appell et al, 1992;Cheung et al, 2003;Lieber et al, 1996;Rodenburg et al, 1993;Yu et al, 2003). Whether these architectural and functional changes could also decrease the efficiency of muscle contraction remains unknown.…”

Mesenchymal Stem Cells Improve Muscle Function Following Single Stretch Injury: A Preliminary Study

“…While all plantar flexors in the model are subject to stretch injury, it is known that biarticular muscles are more prone to disruption [1,42], and that fast twitch fibers appear to be more vulnerable, possibly due to metabolic profile [43,44], higher tensions [45] or relatively shorter optimal lengths of the motor unit [46]. The gastrocnemius is comprised primarily of fast twitch fibers (95% IIB), while the uniarticular soleus muscle is made up of slow twitch (I and IIA) fibers [47].…”

Lack of Effect of Choline Supplement on Inflammation, Muscle Endurance and Injury Indices, and Shooting Accuracy Following Simulated Army Ranger Operation

“…Skeletal muscle proteins catabolism and eccentric contractions along with high oxidative stress could lead to muscular injury in army rangers (8) elevation following vigorous muscle contraction or muscle injury (9). Therefore, plasma CK could be considered to monitor muscular injury in army rangers.…”