Sewright, K. A., Hubal, M. J., Kearns, A., Holbrook, M. T., & Clarkson, P. M. (2008). Sex differences in response to maximal eccentric exercise. Medicine and Science in Sports and Exercise, 40, 242-251.

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This study examined sex differences in strength loss, muscle soreness, and serum creatine kinase and myoglobin levels after high-intensity eccentric exercise of the elbow flexors of the non-dominant arm in men (N = 42) and women (N = 58). Ss performed 50 maximal eccentric contractions. Maximum isometric voluntary contraction was recorded at baseline, immediately after exercise, and at 0.5 (12-14 hours), 3, 4, 7, and 10 days after exercise. Blood samples for serum creatine kinase activity and Mb were taken at baseline and at 4, 7, and 10 d after exercise. Soreness was evaluated at baseline and at 0.5, 3, 4, 7, and 10 days after exercise.

Women experienced significantly greater relative strength loss immediately after exercise than men. A greater percentage of women experienced more than 70% strength loss immediately after exercise. Men exhibited a larger creatine kinase response partly because there were more men who were high responders. There were no significant differences between the sexes for serum myoglobin or soreness measures. Generally, stronger but low relationships among creatine kinase, soreness, and strength-loss measures were found in men.

Implication. After eccentric exercise, women experience greater immediate strength loss than men and were more likely to be high responders for immediate strength loss; men experienced greater serum creatine kinase activity than women and were more likely to be high responders for increased serum creatine kinase. The explanation for high responders to eccentric exercise remains unknown.

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