Exercise-induced skeletal muscle damage and adaptation following repeated bouts of eccentric muscle contractions

Repeated bouts of eccentric muscle contractions were used to examine indirect indices of exercise-induced muscle damage and adaptation in human skeletal muscle. Twenty-four subjects (18 females, 6 males) aged 20.0 +/- 1.4 years (mean +/- S.D.) performed an initial bout of either 10 (n = 7), 30 (n = 9) or 50 (n = 8) maximum voluntary eccentric contractions of the knee extensors, followed by a second bout of 50 contractions 3 weeks later using the same leg. Muscle soreness was elevated after all bouts (P 0.05). We conclude that skeletal muscle adaptation can be brought about by a single bout of relatively few eccentric muscle contractions. Increasing the number of eccentric muscle repetitions did not result in an increased prophylactic effect on skeletal muscle.