The Acute Effect of Increasing Resistance Training Workload Volume on Muscle Damage Markers and Performance in Heavy...

Despite the widespread use of periodized resistance training by athletes, the acute physiological and performance responses when athletes transition between mesocycles with differing workload volumes remain poorly understood. This study examined the acute effect of increasing resistance training workload volume on muscle damage markers and field-specific performance in heavy resistance-trained youth athletes. Eighteen male, rugby league players (age 17.4 ± 0.8 years; body mass 80.2 ± 13.7 kg; height 1.8 ± 0.1 m) completed a four-week mesocycle to develop maximal strength (70-100% of one repetition maximum [1RM]). Muscle damage (i.e., delayed onset muscle soreness [DOMS] and creatine kinase [CK]) and performance measures (i.e., drop jump, plyometric push-up, 40 m sprint and repeated agility) were assessed prior to and at 24 h (T24) and 48 h (T48) following the last session of the strength mesocycle (Week 5). A hypertrophy session (35-70% of 1RM) was then included in Week 6 with data collected prior to and at T24 and T48. Compared with the strength (Week 5) modality, the hypertrophy (Week 6) modality resulted in greater DOMS (41.6 ± 22.7%; effect size [ES] = 0.97-1.12) and modestly higher CK (26.7 ± 47.8%; ES = 0.6). Larger declines in field-specific performance measures were also shown during the HYP modality than STR modality for 20 m sprint performance (-2.1 ± 4.3%; ES = 0.7) and agility performance (-1.1 ± 4.2%; ES = 0.6). There were more modest reductions in drop jump performance (-4.1 ± 7.2%; ES = 0.7) during the HYP modality than in the STR modality, although caution should be given as two separate force plate systems were combined due to technical difficulties. Increasing workload volume was associated with greater muscle damage and modest differences in selected field-specific performance measures following several weeks of maximal strength training. These findings provide preliminary insight into the acute responses to increases in resistance training workload volume. Coaches should monitor athletes' acute responses during fluctuations in workload volume and consider strategies to help maintain training quality in youth athletes.