Figure 3. Time course of changes in P20/P100 ratio after 10, 50 and 100 drop jumps (DJ), as well as within 1, 4, 8, 24, 48 and 72 h after SSE (mean SD). P20 and P100 - muscle contraction force evoked by stimulating quadriceps muscle at 20 Hz and 100 Hz frequencies (mean ± SD). SSE - stretch-shortening exercise (100 DJs were performed from 0.5 m with counter-movement to 90 degrees in the knee with immediate maximal rebound, with 30 s interval between the jumps). The dashed line indicates the pre-exercise mean level. * p < 0.05 compared to pre-exercise P20/P100 ratio.