Rating of perceived exertion as an indirect indicator of velocity loss during power back squat exercise with moderate loads.

INTRODUCTION: It's important to maintain high propulsive velocity and to avoid severe velocity loss during power-aimed resistance exercises. However, it is hard to measure velocity loss in a timely manner without special devices. This study examined the validity of using ratings of perceived exertion (RPE) as velocity loss marker in power back squat (BS) with different repetition settings. METHODS: Seventeen trained males performed three BS tasks with low, medium, and high repetitions at 65% of their one-repetition maximum. RPE, surface electromyography, and concentric velocity were assessed across all conditions. Peak root mean square (RMS) and median frequency (MDF) were calculated from the surface electromyography data. RESULTS: Significant effects were observed across experimental conditions for average RPE and average velocity loss, (p < 0.001), while no significant difference was found in average RMS and MDF. As the lifting tasks progressed, significant effects of repetition were observed in RPE, RMS, and MDF (all p < 0.001). When comparing conditions, significant differences were found among the three in RPE and velocity loss (p < 0.001), whereas no significant effect of condition was observed in RMS and MDF. DISCUSSION: RPE was a significant predictor of velocity loss within individuals (p = 0.002), and this relationship could be expressed as an RPE of 3.8 for a 10% velocity loss. These findings indicate a device-free reference that can be incorporated into established RPE-based autoregulation of velocity loss threshold during power BS at moderate load.