Effects of resistance training based on optimum power load and time under tension on mechanical variables and repetition number in the vertical jump performance of trained individuals

The aim of this study was to analyze the effects of resistance training (RT) based on optimum power load (OPL) and time under tension (TUT) on mechanical variables and the number of repetitions in the vertical jump performance of trained individuals. Twenty-five trained individuals participated in two sessions: one for OPL testing and another for the intervention consisting of 5 sets of 20 seconds of TUT. Data were collected on mechanical variables, number of repetitions, rating of perceived exertion (RPE), and countermovement jump (CMJ) and squat jump (SJ) tests, before and after the intervention. There was a significant decline in CMJ and SJ performance in terms of flight time, height, and absolute and relative power ( p < 0.05). TUT was lower in set 5 (S5) compared to sets 1 (S1), 2 (S2), and 4 (S4) ( p < 0.05). Velocity was lower in S5 compared to S1, S2, set 3 (S3), and S4 ( p < 0.05). Power was higher in S1 compared to S4 and S5 ( p < 0.05). Force was lower in S4 compared to S1, S2, and S3 ( p < 0.05). Mechanical work was lower in S5 compared to S1, S2, S3, and S4 ( p < 0.05). RPE was lower in S1 compared to S2, S3, S4, and S5 ( p < 0.05). The RT protocol based on OPL and TUT led to reductions in mechanical variables across the five 20-second sets, especially from S4 onward. These reductions may have reflected a progressive accumulation of neuromuscular fatigue, as evidenced by the decline in vertical jump test performance and the increase in RPE.