1.. A role of the immune system in muscular adaptation to physical exercise
has been suggested but data from controlled human studies are scarce. The
present study investigated immunological events in human blood and skeletal
muscle by immunohistochemistry and flow cytometry after eccentric cycling
exercise and multiple biopsies.
2. Immunohistochemical detection of neutrophil- (CD11b, CD15), macrophage-
(CD163), satellite cell- (CD56) and IL-1 beta -specific antigens increased
similarly in human skeletal muscle after eccentric cycling exercise togethe
r with multiple muscle biopsies, or multiple biopsies only.
3. Changes in immunological variables in blood and muscle were related, and
monocytes and natural killer (NK) cells appeared to have governing functio
ns over immunological events in human skeletal muscle.
4. Delayed onset muscle soreness, serum creatine kinase activity and C-reac
tive protein concentration were not related to leukocyte infiltration in hu
man skeletal muscle.
5. Eccentric cycling and/or muscle biopsies did not result in T cell infilt
ration in human skeletal muscle. Modes of stress other than eccentric cycli
ng should therefore be evaluated as a myositis model in human.
6. Based on results from the present study, and in the light of previously
published data, it appears plausible that muscular adaptation to physical e
xercise occurs without preceding muscle inflammation. Nevertheless, leukocy
tes seem important for repair, regeneration and adaptation of human skeleta