Leukocytes, cytokines, growth factors and hormones in human skeletal muscle and blood after uphill or downhill running

Abstract

Muscular adaptation to physical exercise has previously been described as a repair process following tissue damage. Recently, evidence has been published to question this hypothesis. The purpose of this study was to investigate inflammatory processes in human skeletal muscle and epimysium after acute physical exercise with large eccentric components. Three groups of subjects (n = 19) performed 45 min treadmill running at either 4 deg (n = 5) or 8 deg (n = 9) downhill or 4 deg uphill (n = 5) and one group served as control (n = 9). One biopsy was taken from each subject 48 h post exercise. Blood samples were taken up to 7 days post exercise. Compared to the control group, none of the markers of inflammation in muscle and epimysium samples was different in any exercised group. Only subjects in the Downhill groups experienced delayed onset of muscle soreness (DOMS) and increased serum creatine kinase activity (CK). The detected levels of immunohistochemical markers for T cells (CD3), granulocytes (CD11b), leukaemia inhibitory factor (LIF) and hypoxia-inducible factor 1β (HIF-1β) were greater in epimysium from exercised subjects with DOMS ratings >3 (0-10 scale) compared to exercised subjects without DOMS but not higher than controls. Eccentric physical exercise (downhill running) did not result in skeletal muscle inflammation 48 h post exercise, despite DOMS and increased CK. It is suggested that exercise can induce DOMS by activating inflammatory factors present in the epimysium before exercise. Repeated physical training may alter the content of inflammatory factors in the epimysium and thus reduce DOMS.

Plasma cytokine response, lipid peroxidation and NF-κB activation in skeletal muscle following maximum progressive swimming

“…Many investigators have reported no effect of exercise on IL-10 secretion (15,31), while others have observed increased plasma IL-10 levels following exercise (17,32). Similar to the present study, Brenner et al (22) have described a reduction in plasma IL-10 levels following "all-out" cycling (5 min, 90% of VO 2max ), supporting the concept that the pattern and magnitude of the IL-10 response vary with exercise intensity and duration.…”

Changes in neutrophil count, creatine kinases and muscle soreness after repeated bouts of downhill running

“…quadriceps) move through the swing-lengthening phase of the running motion. If the primary force is only applied at the end of the action, it is possible that the primary stress is on collagen and tendon structures outside the muscle fibre; 10 this would be supported by findings of Malm and colleagues, 11,12 who D. Gastrocnemius suggest that after downhill running, inflammatory factors are present in muscle epimysium and that the focal injury does not exist in muscle.…”

“…Previous studies, using downhill running, have generally taken blood samples starting at 24 h after the exercise bout. 2,3,12 We believe this is the first study to demonstrate that significant differences occur as early as 3 h after the downhill run.…”

“…On the other hand, in the present study and in a previous study, 21 the mode of exercise involved downhill running; it is proposed that this be regarded as low intensity, high repetitions aerobic-like eccentrics. 11,12,21 Although much emphasis has been placed on differences in training adaptations associated with high-force resistance-like exercise, 14 versus low-force, high-repetitions, such as occurs in aerobic-like exercise, surprisingly, these differences have been virtually ignored in terms of exercise-induced muscle damage.…”

Efeito do exercício no sistema imune: resposta, adaptação e sinalização celular

“…However, during excessive prolonged exercise (>3h), the concentration of circulating NK cells may return to the pre-exercise level, or even become lower 62 . It is hypothesized that this decrease is due to the migration of these cells to sites of muscular injury 63 . Some studies demonstrate that the two subgroups, CD56bright and CD56dim, increase during exercise; however, there is a differential mobilization between them.…”