Importance of satellite cells in the strength recovery after eccentric contraction-induced muscle injury.

The purpose of this study was to determine if the elimination of satellite cell proliferation using gamma-irradiation would inhibit normal force recovery after eccentric contraction-induced muscle injury. Adult female ICR mice were implanted with a stimulating nerve cuff on the common peroneal nerve and assigned to one of four groups: 1) irradiation- and eccentric contraction-induced injury, 2) eccentric contraction-induced injury only, 3) irradiation only, and 4) no intervention. Anterior crural muscles were irradiated with a dose of 2,500 rad and injured with 150 in vivo maximal eccentric contractions. Maximal isometric torque was determined weekly through 35 days postinjury. Immediately after injury, maximal isometric torque was reduced by approximately 50% and had returned to normal by 28 days postinjury in the nonirradiated injured mice. However, torque production of irradiated injured animals did not recover fully and was 25% less than that of injured nonirradiated mice 35 days postinjury. These data suggest that satellite cell proliferation is required for approximately half of the force recovery after eccentric contraction-induced injury.