Effects of Combining PNF With NMES in Young Football Players

Hamstring strains are increasingly common in sports, particularly in football, where they are among the most frequent injuries. Stretching techniques such as proprioceptive neuromuscular facilitation (PNF) are commonly used to improve muscle flexibility and reduce injury risk. A specific variant, contract-relax PNF (crPNF), involves alternating passive stretching with voluntary muscle contractions. Recent approaches suggest that applying neuromuscular electrical stimulation (NMES) during the contraction phase of crPNF may further enhance its effectiveness. This study aims to compare the short-term effects of two active stretching protocols on hamstring flexibility in young male football players. One group will perform crPNF with sham NMES, while the other will perform crPNF with NMES during the contraction phase. A secondary objective is to assess whether either protocol affects vertical jump performance, a key ability in football.