Abstract
The movement of leukocytes (e.g., neutrophils and macrophages) into skeletal muscle is a critical response after a sports-related injury. Age could influence this response. The major objectives of the study were to determine whether there is a relationship between age and the degree of (1) leukocyte response and (2) muscle recovery. The left plantarflexor muscles of 42 young and adult male mice underwent eccentric contractions, which can cause injury. After 1 or 5 days, leukocyte infiltration and muscle recovery were assessed in the soleus or medial gastrocnemius muscles. No relationship between age and leukocyte infiltration was found (P = .36). Neutrophils, but not macrophages, were detected at 1-day recovery. A significant relationship between age and muscle recovery was detected (P = .0498), suggesting that muscle recovery may be decreased with increased age.