218970.fig.002a
(a)
218970.fig.002b
(b)
218970.fig.002c
(c)
218970.fig.002d
(d)
218970.fig.002e
(e)
218970.fig.002f
(f)
Figure 2: 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 after bout 1 and bout 2 in boys ( ), young adult males ( ), and elderly males ( ) (mean ± SD). *,** and , compared with the before-exercise level; # , compared with bout 1.