NCT07075497

Effects of Combining PNF With NMES in Young Football Players

Short Term Effects of Proprioceptive Neuromuscular Facilitation Combined With Neuromuscular Electrical Stimulation in Young Football Players: a Randomized Clinical Trial

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 47 (actual)
• Sponsor: Cardenal Herrera University · Academic / Other
• Sex: All
• Age: 10 Years – 18 Years
• Healthy volunteers: Accepted

Summary

Hamstring muscle injuries are common in sports like football and often lead to extended periods of inactivity. This study aims to compare the effects of two different stretching programs on hamstring flexibility, with a secondary focus on jumping performance in young football players. One group will perform a proprioceptive neuromuscular facilitation (PNF) stretching protocol combined with neuromuscular electrical stimulation (NMES), while the other group will follow the same PNF protocol with a placebo NMES.

Detailed description

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.

Conditions

• Hamstring Flexibility
• Hamstring Muscle Tightness

Interventions

Type	Name	Description
OTHER	Neuromuscular electrical stimulation (NMES)	NMES is applied during each 10-second isometric hamstring contraction using an Enraf Nonius TensMed S82 stimulator delivering biphasic, symmetric rectangular pulses at 50 Hz with a 250 µs pulse width. Two 5 × 5 cm self-adhesive electrodes are placed on the hamstrings-one approximately two finger-breadths below the gluteal fold and the other over the distal third of the muscle belly. Stimulation intensity is individually titrated to each participant's maximal motor threshold-eliciting a strong, yet painless, contraction-and the exact milliamperage is recorded for each leg. Elastic straps over the pelvis and distal thigh maintain pelvic anteversion and knee extension. During each session, one researcher secures limb positioning while a second adjusts and logs NMES intensity and cues the timing of the 10 s contraction and ensuing 30 s passive stretch.
OTHER	Sham Neuromuscular electrical stimulation (NMES)	Sham NMES is delivered during each 10 s isometric hamstring contraction using an Enraf Nonius TensMed S82 stimulator with biphasic, symmetric rectangular pulses (50 Hz, 250 µs pulse width). Two 5 × 5 cm self-adhesive electrodes are placed on the hamstrings-one two finger-breadths below the gluteal fold and one over the distal third of the muscle belly. Intensity is individually set to the sensory threshold, defined as the minimal current producing a slight tingling without any visible muscle response; this milliamperage is recorded for each leg. Elastic straps over the pelvis and distal thigh maintain pelvic anteversion and full knee extension. During each session, one researcher secures limb positioning while a second adjusts and logs the NMES intensity and cues the 10 s contraction timing.
OTHER	Contract-Relax PNF (crPNF)	The crPNF Group engages in an isolated contract-relax proprioceptive neuromuscular facilitation (crPNF) stretching protocol. Participants are positioned in a long sitting posture with maximum knee extension until they feel a moderate-strong stretch sensation, without pain. Each stretch lasts for 30 seconds, followed by a 10-second maximal voluntary isometric contraction of the hamstrings. Participants complete three cycles of stretch and contraction. One researcher maintains the stretch position while a second researcher controls the timing of the stretching and contractions.

Timeline

• Start date: 2025-07-11
• Primary completion: 2025-07-24
• Completion: 2025-07-27
• First posted: 2025-07-20
• Last updated: 2025-11-17

Locations

1 site across 1 country: Spain