Comparative effects of proprioceptive neuromuscular facilitation hold-relax and dynamic stretching on hamstring flexibility, sprint performance, and perceived exertion in adolescent sprinters

Abstract

Background and Study Aim. Stretching is commonly used to support physical performance and preparation in sprint training. Different approaches are applied to influence muscle function and readiness for activity. The study investigated the comparative efficacy of proprioceptive neuromuscular facilitation hold-relax (PNF-HR) and dynamic stretching (DS) on hamstring flexibility, sprint performance, and perceived exertion in adolescent male sprinters. Materials and Methods. The study included eighty-four adolescent male sprinters (aged 15–18 years) recruited from three training academies in Lahore. Participants were randomly allocated to the PNF-HR group, DS group, or control group. The experimental groups completed three supervised sessions per week. Hamstring flexibility was assessed using the Active Knee Extension Test. Sprint performance was assessed using 30 m dash times. Perceived exertion was assessed using the Borg CR-10 scale. Data were collected at baseline, after four weeks, and after eight weeks. Results. Mixed-model ANOVA showed significant time × group interactions for all primary outcomes (p < .001). These results indicate differential changes between groups over time. Ninety-five percent confidence intervals and effect sizes were calculated for the primary outcomes. Post hoc analysis showed greater improvement in flexibility in the PNF-HR group (Δ 16.2°, d = 2.14) compared with the DS group (Δ 9.8°, d = 1.31) and the control group. Both PNF-HR and DS improved 30 m sprint time. The DS group showed a greater reduction (-0.21 s) compared with the PNF-HR group (-0.14 s). Conclusions. Perceived exertion was higher in the PNF-HR group (mean = 7.4) than in the DS group (mean = 4.1). The PNF-HR method improved flexibility. The DS modality was associated with better sprint performance and lower perceived effort. A targeted stretching modality should be selected based on the training goal in adolescent athletes. Future studies should examine long-term injury rates and the combined use of these modalities within training programs.