Acute Effects of Contract-Relax PNF With and Without Neuromuscular Electrical Stimulation on Hamstring Flexibility and Jump Performance in Adolescent Soccer Players: A Randomized Controlled Trial

This study investigates whether combining motor-threshold neuromuscular electrical stimulation (NMES) with contract-relax proprioceptive neuromuscular facilitation (PNF-CR) stretching enhances hamstring flexibility compared to sensory-threshold NMES, without negatively impacting vertical jump performance in adolescent soccer players. The results indicate that both interventions improved hamstring flexibility similarly, with no significant differences between groups, and neither method adversely affected jump performance. Thus, the addition of motor-threshold NMES does not provide additional benefits for flexibility gains in this population.