Time trial performance, muscular endurance, and leg LM in the PLA (n = 26) and PRO (n = 30) groups. The open symbols represent individual cases and the black lines represent mean ± SD. A, Changes in time trial performance over the 12-wk intervention period in the PLA (n = 26) and PRO (n = 30) groups. Mixed-model design ANOVA indicated a significant reduction in time to complete the time trial (time effect, P < 0.0001), with no differences between groups (time–treatment interaction, P = 0.22). B, Changes in muscular endurance over the 12-wk intervention period in the PLA (n = 26) and PRO (n = 30) groups. Mixed-model design ANOVA indicated a significant increase in work completed during 30 reciprocal contractions (time effect, P < 0.0001), with no differences between groups (time–treatment interaction, P = 0.84). C, Changes in leg LM over the 12-wk intervention period in the PLA (n = 26) and PRO (n = 30) groups. Mixed-model design ANOVA indicated a significant increase in leg LM (time effect, P < 0.0001), which tended to be greater in the PRO group (time–treatment interaction, P = 0.073).