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 .
Changes in hardness of the human elbow flexor muscles after eccentric exercise
Abstract The purpose of this study was to investigate changes in muscle hardness after  eccentric exercise of the elbow flexors muscles that produce muscle shortening and swelling . To assess muscle hardness , a pressure method was used in which the force required to deform the tissue ( skin , subcutaneous tissue , muscle ) was recorded . Eleven healthy male students performed 24 maximal eccentric actions of the elbow flexor muscles with their non-dominant arms . Muscle hardness , maximal isometric force ( MIF ) , muscle soreness , plasma creatine kinase ( CK ) activity , relaxed elbow joint angle ( RANG ) , upper-arm circumference ( CIR ) and B-mode ultrasound transverse images were measured before , immediately after , and 1–5 days after exercise . A long-lasting decrease in MIF , muscle swelling shown by increases in CIR and muscle thickness , large increases in plasma CK activity , and development of muscle soreness indicated that damage occurred to the elbow flexor muscles . The RANG had decreased by approximately 20 ° at 1–3 days after exercise and showed a gradual recovery thereafter . The CIR increased gradually after exercise and peaked on day 5 post-exercise , the mean amount of increase in CIR being 18 mm . Muscle hardness measured at the relaxed elbow position did not change until 3 days after exercise , but increased significantly ( P < 0.01 ) on days 4 and 5 post-exercise . On the other h and , muscle hardness measured when forcibly extending the shortened elbow joint increased significantly ( P < 0.01 ) with time and peaked at 3 days after exercise . Muscle hardness assessed by the pressure method seems to reflect changes in muscle stiffness and swelling
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 .