Divergent Performance Outcomes Following Resistance Training Using Repetition Maximums or Relative Intensity.

PURPOSE: The purpose of our investigation was to compare repetition maximum (RM) to relative intensity using sets and repetitions (RISR) resistance training (RT) on measures of training load, vertical jump, and force production in well-trained lifters.

METHODS: Fifteen well-trained (isometric peak force= 4403.61+664.69 N, mean+SD) males underwent RT 3 d·wk-1 for 10-weeks in either an RM group (n=8) or RISR group (n=7). Weeks 8-10 consisted of a tapering period for both groups. The RM group achieved a relative maximum each day while the RISR group trained based on percentages. Testing at five time-points included unweighted (<1kg) and 20kg squat jumps (SJ), counter-movement jumps (CMJ), and isometric mid-thigh pulls (IMTP). Mixed design ANOVAs and effect size using Hedge's g were used to assess within and between-group alterations.

RESULTS: Moderate between-group effect sizes were observed for all SJ and CMJ conditions supporting the RISR group (g=0.76-1.07). A small between-group effect size supported RISR for allometrically-scaled isometric peak force (g=0.20). Large and moderate between-group effect sizes supported RISR for rate of force development from 0-50ms (g=1.25) and 0-100ms (g=0.89). Weekly volume load displacement was not different between groups (p>0.05), however training strain was statistically greater in the RM group (p<0.05).

CONCLUSIONS: Overall, this study demonstrated that RISR training yielded greater improvements in vertical jump, rate of force development, and maximal strength compared to RM training, which may partly be explained by differences in the imposed training stress and the use of failure/non-failure training in a well-trained population.