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NCT Number: NCT07171385

Posterior Chain EMG Patterns in Athletes With and Without Hamstring Injury

This cross-sectional observational study investigated posterior chain muscle activation patterns in football players with and without a history of hamstring strain injury. Forty-two male athletes were assessed using surface electromyography (sEMG) during Nordic Hamstring Curl, Kettlebell Swing, and Supine Sliding Leg Curl exercises. Results demonstrated persistent deficits in biceps femoris, gluteus maximus, latissimus dorsi, and iliocostalis lumborum activation in previously injured athletes compared to controls, suggesting that neuromuscular alterations extend beyond the hamstring itself and may increase reinjury risk.

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Key information

Conditions

Muscle Strain Athletic Injuries Nervous System Diseases Neuromuscular Diseases Sprains and Strains Wounds and Injuries

Age range

18 year–30 year

Sex eligibility

Male

Study type

Observational

Primary location

University of Health Sciences

Ankara, Etlik, 06100, Turkey (Türkiye)

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Male football players, aged 18-30 years
  • Body mass index (BMI) between 18.5-24.9 kg/m²
  • Voluntary participation and written informed consent
  • Ability to perform all test exercises (Nordic Hamstring Curl, Kettlebell Swing, Supine Sliding Single-Leg Curl)
  • For injured group: unilateral hamstring strain within the past 6 months
  • For control group: no hamstring injury within the past 6 months

Exclusion criteria

  • Professional sports background
  • Lower or upper extremity injury within the last year (other than index hamstring strain for the injured group)
  • Neurological, musculoskeletal, respiratory, or cardiovascular conditions limiting participation
  • Recent spinal surgery
  • Acute low-back or lower-limb pain
  • Sensory impairments interfering with performance
  • History of malignancy

Treatment and study plan

Nordic Hamstring Curl (NHC)

Other

Knee-dominant eccentric hamstring strengthening exercise performed on a padded surface. Participants control the descent of the torso while knees remain fixed, emphasizing eccentric activation of hamstring muscles.

Kettlebell Swing (KS)

Other

Hip-dominant ballistic movement involving rapid hip flexion-extension using a kettlebell (16-20 kg depending on participant's ability). Each repetition includes concentric, isometric, and eccentric phases standardized by metronome pacing.

Supine Sliding Single-Leg Curl (SSLC)

Other

Closed-chain exercise performed in supine position with heels placed on sliding discs. One leg is extended while the other leg performs concentric-eccentric sliding curl.

Primary outcomes

  1. Gluteus Maximus Activation (%MVIC)

    Time frame: Single laboratory visit; measurements during 3 repetitions of each exercise (Nordic Hamstring Curl, Kettlebell Swing, Supine Sliding Single-Leg Curl)

    Surface EMG amplitude (RMS) normalized to MVIC, averaged across three functional exercises. Mean %MVIC compared between groups.

  2. Biceps Femoris Long Head Activation (%MVIC)

    Time frame: Single laboratory visit; measurements during 3 repetitions of each exercise (Nordic Hamstring Curl, Kettlebell Swing, Supine Sliding Single-Leg Curl)

    Surface EMG amplitude (RMS) normalized to MVIC. Mean %MVIC across repetitions compared between injured and healthy athletes.

  3. Latissimus Dorsi Activation (%MVIC)

    Time frame: Single laboratory visit; measurements during 3 repetitions of each exercise (Nordic Hamstring Curl, Kettlebell Swing, Supine Sliding Single-Leg Curl)

    Surface EMG amplitude (RMS) normalized to MVIC, averaged across three functional exercises. Mean %MVIC compared between groups.

  4. Iliocostalis Lumborum Activation (%MVIC)

    Time frame: Single laboratory visit; measurements during 3 repetitions of each exercise (Nordic Hamstring Curl, Kettlebell Swing, Supine Sliding Single-Leg Curl)

    Surface EMG amplitude (RMS) normalized to MVIC. Mean %MVIC across repetitions compared between injured and healthy athletes.

Sponsors and collaborators

Lead sponsor

Ankara Yildirim Beyazıt University

Other

Collaborators

  • Eskisehir Technical University
  • Istanbul Gelisim University
  • Manisa Celal Bayar University
  • Mersin University
  • Saglik Bilimleri Universitesi
  • T.C. Dumlupınar Üniversitesi
  • Çanakkale Onsekiz Mart University

Registry information

Official study title

Persistent Neuromuscular Deficits in the Posterior Kinetic Chain Following Hamstring Strain Injury: A Cross-Sectional Study Using EMG

Important dates

Study start
2023
Primary completion
2023
Study completion
2024
First posted
Sep 12, 2025
Registry last updated
Sep 12, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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