Optimal inter-trial intervals spacing for learning volleyball overhand serve

Studies on spacing of practice investigate the effects of the execution/rest ratio on the acquisition of motor skills. For research purposes, this spacing of practice is dichotomized as massed or distributed practice. It can be manipulated as the inter-trial interval, corresponding to the period of time between the end of one attempt and the beginning of the next, separating the responses. Most studies investigated the inter-trial interval with simple tasks, but results are not conclusive when testing with complex sports motor skills. Purpose: This study explored the spacing of practice through three inter-trial intervals on learning a complex sports motor skill. Material and Methods: Participants (n=36, aged 13.8 ± 1.0) performed the volleyball overhand serve from one side of the court, aiming to reach a target on the other side. Three experimental groups were carried out: one massed practice (1-second inter-trial interval) and two distributed practices (inter-trial intervals of 15-second and 40-second). All groups performed 12 trials in the pre-test, 200 in the acquisition phase, and 12 in the retention test. Results: The results revealed higher performance accuracy and consistency of the shorter inter-trial interval than longer inter-trial intervals, observed during the acquisition and retention test, indicating better learning for the massed inter-trial interval. Conclusions: The inter-trial interval spacing led to different levels of learning of volleyball overhand serve. The shorter inter-trial interval was demonstrated to be better for parameters learning of sports motor skills, allowing information to be processed more efficiently in working memory, contributing to enhanced learning of sports motor skills. Massed practice, in this context, did not induce fatigue for performance loss. The coaches are advised to optimize training schedules incorporating massed practice for the development of complex sports motor skills.