Conclusion Overall , our findings do not support the presence of a secondary loss of strength following an acute muscle injury , and strongly suggest that strength , on average , recovers steadily over the first 3 days post-injury
Background An immediate loss of strength follows virtually all types of muscle injury but there is debate whether the initial strength loss is maximal or if a secondary loss of strength occurs during the first 3 days post-injury .
Objective The objective of this analysis was to conduct a systematic review and meta- analysis of the research literature to determine if a secondary loss of strength occurs after an injurious initiating event .
Cellular adaptation to repeated eccentric exercise-induced muscle damage.
Eccentrically biased exercise results in skeletal muscle damage and stimulates adaptations in muscle , whereby indexes of damage are attenuated when the exercise is repeated . We hypothesized that changes in ultrastructural damage , inflammatory cell infiltration , and markers of proteolysis in skeletal muscle would come about as a result of repeated eccentric exercise and that gender may affect this adaptive response . Untrained male ( n = 8) and female ( n = 8) subjects performed two bouts ( bout 1 and bout 2 ) , separated by 5.5 wk , of 36 repetitions of unilateral , eccentric leg press and 100 repetitions of unilateral , eccentric knee extension exercises ( at 120 % of their concentric single repetition maximum ) , the subjects ' contralateral nonexercised leg served as a control ( rest ) . Biopsies were taken from the vastus lateralis from each leg 24 h postexercise . After bout 2 , the postexercise force deficit and the rise in serum creatine kinase ( CK ) activity were attenuated . Women had lower serum CK activity compared with men at all times ( P < 0.05 ) , but there were no gender differences in the relative magnitude of the force deficit . Muscle Z-disk streaming , quantified by using light microscopy , was elevated vs. rest only after bout 1 ( P < 0.05 ) , with no gender difference . Muscle neutrophil counts were significantly greater in women 24 h after bout 2 vs. rest and bout 1 ( P < 0.05 ) but were unchanged in men . Muscle macrophages were elevated in men and women after bout 1 and bout 2 ( P < 0.05 ) . Muscle protein content of the regulatory calpain subunit remained unchanged whereas ubiquitin-conjugated protein content was increased after both bouts ( P < 0.05 ) , with a greater increase after bout 2 . We conclude that adaptations to eccentric exercise are associated with attenuated serum CK activity and , potentially , an increase in the activity of the ubiquitin proteosome proteolytic pathway
Conclusion Overall , our findings do not support the presence of a secondary loss of strength following an acute muscle injury , and strongly suggest that strength , on average , recovers steadily over the first 3 days post-injury
Background An immediate loss of strength follows virtually all types of muscle injury but there is debate whether the initial strength loss is maximal or if a secondary loss of strength occurs during the first 3 days post-injury .
Objective The objective of this analysis was to conduct a systematic review and meta- analysis of the research literature to determine if a secondary loss of strength occurs after an injurious initiating event .