Frontiers in Sports and Active Living | 2026
Authors: Hirayama K.; Nakai S.; Kubo T.; Takei S.
DOI: 10.3389/fspor.2026.1698649
Journal: Frontiers in Sports and Active Living
Year: 2026
Publisher: Frontiers Media SA
Document Type: Article
Open Access: All Open Access; Gold Open Access; Green Open Access
Cited by: 0
This study examined whether verbal instruction emphasizing force exertion during the braking phase of rebound jumps can acutely enhance the reactive strength index (RSI), a key indicator of stretch–shortening cycle performance linked to sprinting and change-of-direction ability. Seventeen physically active men without plyometric training experience were randomly assigned to an intervention (n = 8) or control group (n = 9). Both groups performed repeated rebound jumps under standard instruction. The intervention group additionally received braking-phase–focused instruction. RSI significantly increased only in the intervention group (p < 0.05), accompanied by greater soleus muscle preactivation before ground contact. These findings suggest that simple, targeted verbal instruction can acutely optimize neuromuscular strategies during plyometric tasks, offering coaches a practical tool for enhancing explosive performance without long-term training. © 2026 Hirayama, Nakai, Kubo and Takei.
ankle hop; cueing; electromyography; plyometrics; stretch–shortening cycle