Abstract
We analyzed the effects of load magnitude and bar velocity variables on
sensitivity to fatigue. Seventeen resistance-trained men (age=25.7±4.9 years;
height=177.0±7.2 cm; body mass=77.7±12.3 kg; back-squat 1RM=145.0±33.9 kg;
1RM/body mass=1.86) participated in the study. Pre- and post-exercise changes in
the mean propulsive velocity (MPV) and peak velocity (PV) in the back-squat at
different intensities were compared with variations in the countermovement jump
(CMJ). CMJ height decreased significantly from pre- to post-exercise (∆%=−7.5 to
−10.4; p<0.01; ES=0.37 to 0.60). Bar velocity (MPV and PV) decreased across
all loads (∆%=−4.0 to −12.5; p<0.01; ES=0.32 to 0.66). The decrease in
performance was similar between the CMJ, MPV (40% and 80% 1RM; p=1.00), and PV
(80% 1RM; p=1.00). The magnitude of reduction in CMJ performance was greater
than MPV (60% 1RM; p=0.05) and PV (40% and 60% 1RM; p<0.01) at the
post-exercise moment. Low systematic bias and acceptable levels of agreement
were only found between CMJ and MPV at 40% and 80% 1RM (bias=0.35 to 1.59;
ICC=0.51 to 0.71; CV=5.1% to 8.5%). These findings suggest that the back-squat
at 40% or 80% 1RM using MPV provides optimal sensitivity to monitor fatigue
through changes in bar velocity.
Keywords
velocity-based training - strength training - neuromuscular fatigue - back-squat
