Force development of dynamic and static contractions in children and adults.

There are still unclarified points remaining in regard to the characteristics of force development in children who are immature in their basic activities in daily living. Moreover, there are morphological, histological, and biochemical differences between immature and mature muscles. In the present study, dynamic elbow flexion and static contractions which were performed by elbow flexors with maximum effort were examined by force-velocity and force-time relationships and electromyograms (EMG) in six-year-old children and in adults. In dynamic contractions with various loads, the force-velocity relationship for children was (P + 5.65) (v + 1.48) = 19.51, and (P + 14.65) (v + 2.26) = 96.21 for adults. The maximum power in children and adults was 22.8 watts and 160.8 watts, respectively. The contraction delay in children was greater than that in adults for every relative load. In static contractions, the maximum rate of force development for children was significantly lower than that for adults at each pre-tension. With an increase in pre-tension, the adult rate showed a tendency to decrease, whereas the rate for children showed no change. The electromechanical delay observed in children was significantly greater than that in adults. For dynamic and static contractions, the contractile speed in children was lower than that in adults.