Effectiveness of Dry Needling in Athletes With Chronic Hamstring Strain

Chronic hamstring strain (CHS) is a common musculoskeletal condition among athletes, particularly in sports involving high-speed running and sudden changes in direction. It is characterized by persistent or recurrent symptoms lasting more than three months and is often associated with reduced muscle flexibility, decreased performance, and an increased risk of reinjury.

Dry needling (DN) has emerged as a therapeutic intervention targeting myofascial trigger points to reduce pain, improve muscle function, and restore neuromuscular control. It is believed to act through both mechanical and neurophysiological mechanisms, including reduction of muscle tension and modulation of pain pathways.

This study aims to investigate the effectiveness of dry needling as an adjunct to conventional physiotherapy in athletes with chronic hamstring strain. Participants will be randomly assigned into two groups. The experimental group will receive dry needling combined with a structured physiotherapy program, while the control group will receive the same physiotherapy program without dry needling.

The physiotherapy program will include stretching exercises, strengthening exercises with an emphasis on eccentric loading, and functional training. Dry needling will be applied to identified trigger points in the hamstring muscles using standard clinical techniques.

Outcome measures will include pain intensity, hamstring flexibility, and functional performance. Assessments will be conducted before and after the intervention period.

The results of this study are expected to provide evidence regarding the added value of dry needling in improving rehabilitation outcomes for athletes with chronic hamstring strain.

• Dry Needling (Procedure): Participants will receive dry needling treatment applied to active myofascial trigger points in the hamstring muscles (biceps femoris, semitendinosus, and semimembranosus). Sterile filiform needles will be inserted into identified trigger points to elicit local twitch responses and reduce muscle pain and tightness. Treatment will be performed in addition to a standardized rehabilitation program including stretching and strengthening exercises for the hamstring muscle group. Sessions will be administered over the study period according to a predefined treatment schedule.
• Standard Rehabilitation Program (Procedure): Participants will receive a standardized rehabilitation program including stretching and eccentric strengthening exercises for hamstring muscles without dry needling.

Primary outcomes

• Pain Intensity [Baseline (pre-intervention) and after 6 weeks of treatment]: Pain intensity in chronic hamstring strain will be assessed using the Visual Analog Scale (VAS), a 10-cm scale ranging from 0 (no pain) to 10 (worst imaginable pain). Measurements will be taken at baseline and after completion of the intervention period to evaluate changes in pain perception.

Secondary outcomes

• Functional Performance [Baseline (pre-intervention) and after 6 weeks of treatment]: Functional outcomes will be assessed using the Lower Extremity Functional Scale (LEFS) to evaluate the impact of intervention on daily and sports-related activities.
• Hamstring Muscle Strength [Baseline (pre-intervention) and after 6 weeks of treatment]: Hamstring muscle strength will be measured using a handheld dynamometer during maximal isometric contraction.
• Hamstring Flexibility [Baseline (pre-intervention) and after 6 weeks of treatment]: Hamstring flexibility will be assessed using the popliteal angle test with a universal goniometer.
• Kicking Speed [Baseline (pre-intervention) and after 6 weeks of treatment]: Kicking speed will be measured using a radar gun to assess football-specific performance.

Sex: Male, ages: 18 Years to 35 Years

Inclusion Criteria:

* Male football players aged 18 to 35 years.
* Diagnosed with chronic hamstring strain (CHS) confirmed by ultrasonography.
* Injury duration of more than 3 months.
* Classified as Grade I or Grade II hamstring strain.
* Currently participating in the competitive phase of football.
* Body Mass Index (BMI) between 21-25 kg/m².

Exclusion Criteria:

* Previous exposure to dry needling therapy.
* Presence of any other current lower limb injuries.
* Participation in another hamstring rehabilitation program.
* Active skin infection at or near the treatment area.
* Bleeding disorders or use of anticoagulant medications.
* Severe needle phobia or psychological intolerance to needling.
* Presence of neuromuscular disorders (e.g., muscular dystrophy or peripheral neuropathy).

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• Amr Anas, BSc, Principal investigator, Cairo University
• Ebtessam Gomaa, PhD, Study director, Cairo University
• Marihan Makary, Study director, Cairo University