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

## TL;DR

This study compares how different hamstring stretching techniques affect flexibility, explosive power, and balance immediately after stretching.

## Contribution

The study identifies PNF stretching as superior to static stretching for acute improvements in flexibility and balance.

## Key findings

- PNF stretching significantly improved hamstring flexibility, broad jump distance, and both static and dynamic balance.
- Static stretching increased flexibility but impaired static balance metrics like COP area and sway velocity.
- PNF is recommended for performance-oriented warm-ups, while static stretching may be better for recovery contexts.

## Abstract

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.