Acute neuromechanical effects of static and PNF hamstring stretching on explosive power and balance

Hamstring stretching is widely incorporated into warm-up routines, yet the acute neuromuscular consequences of different stretching modalities on flexibility, explosive performance, and balance remain unclear.

Using a randomized crossover design, twenty-one healthy young adults completed three conditions: static stretching (SS), proprioceptive neuromuscular facilitation (PNF) stretching, and a no-stretch control (NS). Hamstring flexibility, vertical and broad jump performance, dynamic balance (Y-Balance Test), and static balance via center of pressure (COP) metrics were assessed immediately pre- and post-intervention.

PNF elicited the most favorable acute outcomes, producing significant improvements in hamstring flexibility, broad jump distance, and both static and dynamic balance compared with SS and NS (all p < 0.05). SS increased hamstring flexibility but consistently impaired static balance, reflected by larger COP area, trajectory length, and sway velocity across eyes-open and eyes-closed conditions. Vertical jump height showed no significant differences among conditions. Dynamic balance improved significantly following PNF and partially following SS.

PNF stretching is the most effective modality for enhancing immediate flexibility, horizontal power, and postural stability, making it suitable for performance-oriented warm-ups. In contrast, static stretching may compromise neuromuscular control despite improving hamstring flexibility and is therefore better suited for non-performance or recovery contexts.