Purpose:
The study compared muscle peak power during pneumatic squat exercise with different percentages of load, corresponding to 80%, 100%, and 120% of body mass (BM), in male professional soccer players.

Methods:
The study involved 40 male elite soccer players (25.2 ± 3.6 years; 179.6 ± 6.1 cm; 78.3 ± 5.2 kg; body fat 12.3 ± 3.3%) from a club of the Brazilian first division soccer league participating in national competitions organized by the Brazilian Soccer Confederation. Peak power was assessed by using a pneumatic squat machine (squat power test). The athletes applied different training loads during the squat power test (3 trials with 80% of BM followed by a 5-minute rest to perform attempts with 100% and 120%, respectively).

Results:
The two-way ANOVA yielded main effects for group (F_3,26 = 3.08, p < 0.04) and for timing of measurement F_2,52 = 526.1, p < 0.0001), indicating a significant difference in the absolute peak power of goalkeepers when compared with defenders and midfielders at the loads corresponding to 80%, 100%, and 120% of BM. Intra-group comparison demonstrated a significant increase (p < 0.0001) in the absolute and relative peak power with loads corresponding to 120% of BM when compared with 80% and 100% of BM in all groups (defenders, goalkeepers, midfielders, and forwards).

Conclusions:
The results confirm that loads corresponding to 120% of BM during pneumatic squat exercise contribute to greater absolute and relative peak power.