218970.fig.001a
(a)
218970.fig.001b
(b)
218970.fig.001c
(c)
218970.fig.001d
(d)
218970.fig.001e
(e)
218970.fig.001f
(f)
Figure 1: Voluntary (MVC (a) maximal voluntary contraction force of quadriceps muscle; H of DJs (f) height of drop jumps; VA (e) quadriceps muscle voluntary activation index) and electrically (P20 (b) and P100 (c) muscle contraction force evoked by stimulating quadriceps muscle at 20 Hz and 100 Hz frequencies, resp.; P20/P100 (d) ratio of P20/P100 indicates the level of low frequency fatigue) induced muscle performance before bout 1 and bout 2 in boys ( ), young adult males ( ), and elderly males ( ) (mean ± SD). * , between elderly males and boys; # , compared with young adult males and boys.