Does cluster loading enhance lower body power development in preseason preparation of elite rugby union players?

The purpose of this study was to ascertain whether cluster training led to improved power training adaptations in the preseason preparation of elite level rugby union players. Eighteen highly trained athletes were divided into 2 training groups, a traditional training (TT, N = 9) group and a cluster training (CT, N = 9) group before undertaking 8 weeks of lower body resistance training. Force-velocity-power profiling in the jump squat movement was undertaken, and maximum strength was assessed in the back squat before and after the training intervention. Two-way analysis of variance and magnitude-based inferences were used to assess changes in maximum strength and force, velocity, and power values pretraining to posttraining. Both TT and CT groups significantly (p < 0.05) increased maximum strength posttraining. There was a possibly negative effect for the CT group on maximum strength when compared with that for the TT group (pretraining to posttraining change = 14.6 ± 18.0 and 18.3 ± 10.1%, respectively). There were no significant differences pretraining to posttraining for any jump squat force, velocity, or power measures. However, magnitude-based inferences showed that there was a likely positive effect of CT when compared with that of TT for peak power (pretraining to posttraining change = 7.5 ± 7.0 and 1.0 ± 6.2%, respectively) and peak velocity at 40 kg (pretraining to posttraining change = 4.7 ± 6.1 and 0.0 ± 5.0%, respectively) and for peak velocity at body weight (pretraining to posttraining change = 3.8 ± 3.4 and 0.5 ± 3.8%, respectively). Although both a traditional and cluster training loading pattern improved lower body maximum strength in a highly trained population, the traditional training structure resulted in greater maximum strength adaptation. There was some evidence to support the possible benefit of cluster type loading in training prescription for lower body power development.