Reliability and methodological issues of power assessment during chest presses on unstable surface with different weights.

AIM: The study compares the reliability of peak power (Ppeak) and mean power in acceleration (Pmean acc) and entire concentric phase (Pmean total) of chest presses on the bench and unstable Swiss ball with different weights. METHODS: A group of 32 fit men performed over 2 testing sessions 3 trials of barbell chest presses on the bench and Swiss ball, without and with countermovement, with weights of 40, 60 and 80% 1RM. RESULTS: High values of correlation coefficients (above .80) and no significant differences between trials signify stability of measurement under both stable and unstable conditions. When chest presses were performed on the bench, ICC and SEM% values were in range .97 to .98 and 7.6 to 7.7%, respectively for Pmean total, .96 to .98 and 9.1 to 9.6%, respectively for Pmean acc, and .94 to .97 and 9.2 to 10.0%, respectively for Ppeak. Their values during chest presses on a Swiss ball ranged from .93 to .96 and 8.4 to 9.1%, respectively for Pmean total, from .87 to .90 and 11.7 to 12.2%, respectively for Pmean acc, and from .79 to .82 and 12.1 to 13.4%, respectively for Ppeak at weights of 40 and 60% 1RM, and from .70 to .76 and 17.6 to 19.8%, respectively at weight of 80% 1RM. CONCLUSION: Measurement of peak and mean power during unstable chest presses provides reliable data comparable to those obtained during bench presses under all conditions tested. However, peak values of power measured during unstable chest presses with weights ≥80% 1RM should be interpreted with caution.