Mechanical power output in children aged 11 and 14 years.

Short-term power output in jumping and cycling has been measured in 56 children aged 11 and 14 years. The results showed that the peak power output in cycling (Wb) and jumping (Wp) were closely associated (r = 0.91) but in absolute terms Wb was approximately 34% greater than Wb. There were no significant differences in Wb (or Wp) between the 11-year-old boys and girls, but the 14-year-old boys recorded approximately 25% higher power output values in cycling and jumping than girls of the same age and were approximately twice as powerful as their younger male counterparts. The velocity of movement in cycling (Vb) and jumping (VT) for a given age were identical and independent of sex in the younger children. Peak power output in cycling was reached when force and velocity were equivalent to 50% of their calculated maximal values. When Wb and Wp were related to an anthropometric estimate of leg muscle (plus bone) volume the difference in absolute power output between the children disappeared. The results suggest that the difference between Wp and Wb and the increase in absolute mechanical power output with age is mainly a function of size and the force which can be exerted at the optimal frequency of movement in children.