Countermovement jump analysis: Effects of acoustic and visual stimuli on jump performance in volleyball players evaluated by inertial measurement unit

The ability to perform maximal vertical jumps (VJs) significantly affects athletic performance in several sports, such as volleyball, with a paucity of studies investigating the effects of different sensory stimuli on VJ performance. To the best of our knowledge, no study quantitatively assessed the variations of spatial-temporal and kinetic parameters during Countermovement Jump-Free Arms (CMJ-FA) execution in different acoustic and visual conditions. The aim of the present study is to explore the effects of visual and acoustic stimuli, in conditions considered incentive and disincentive, on CMJ-FA performance via an Inertial Measurements Unit (IMU). Twenty male volleyball athletes were assessed across five sessions, each with 3 CMJ-FA repetitions, performed either without sensory stimulus (NS), with incentive (IAS) and disincentive (DAS) acoustic stimulus, and with incentive (IVS) and disincentive (DVS) visual stimulus. Spatial-temporal and four kinetic parameters were evaluated. Significant differences in disincentive conditions with respect to NS in time of flight phase and jump height were observed. Moreover, in DVS a trend of increase for Impact Index compared to NS was found. Instead, no significant variations were found in incentive conditions compared to NS. These findings highlighted the interference of disincentive conditions on jump performance; moreover, an increase of ground impact force during landing phase in DVS may predispose to muscle-skeletal lower limb injuries. These knowledges could be useful to the sports trainers for improving athletes' control, in order to desensitize them from disincentive conditions, keeping a good performance and decreasing the risk of injuries during the competition.