Twitch contractile properties of plantar flexor muscles were compared in 9- to 10-year-old girls and boys. No significant gender differences (p > .05) in isometric maximal voluntary contraction force and twitch peak force, contraction and relaxation times, and twitch maximal rate of force development in either resting or potentiated state have been observed. However, boys had significantly greater (p < .05) twitch postactivation potentiation and potentiated twitch maximal rate of relaxation than girls. These results indicated that twitch force-potentiation capacity of skeletal muscles prior to puberty is more highly developed in boys than girls.
The authors are with the Institute of Exercise Biology and Physiotherapy, University of Tartu, Tartu, Estonia.