Hernández Davó, JL, Botella Ruiz, J, and Sabido, R. Influence of strength level on the rest interval required during an upper-body power training session. J Strength Cond Res 31(2): 339–347, 2017—The present study aimed to investigate the influence of subjects' strength level on both the ability to maintain power output performance and the physiological and perceived exertion responses during a power training session when different rest intervals (RI) are used. Thirty-eight (18 men and 20 women) subjects were divided into a stronger or weaker group based on their ability to produce peak power output. Testing was performed using the same protocol (5 sets of 8 repetitions with 40% of 1 repetition maximum) in the bench press throw exercise, but differing the RI between sets (1, 2, and 3 minutes). During the sessions, mechanical (peak power), physiological ([La−]) and perceptual (RPE) variables were measured. In addition, delayed onset muscular soreness (DOMS) 24 and 48 hours after the training session was reported. Both stronger and weaker (men and women) groups showed significant impairments in mechanical, physiological, and perceptual data when resting 1 minute. Nevertheless, although stronger groups were able to sustain power output over the sets when using the 2-minute RI, weaker groups needed at least 3 minutes to maintain power output performance. Therefore, strength level heavily influences the rest interval required during a power training session and should be taken into account when prescribing such training sessions.