An observational study in Hamstring Injury, sponsored by Universidad de Extremadura. Completed at 1 site in Spain. Open to male participants aged 18 Years to 35 Years. Per ClinicalTrials.gov, last updated 2026-10-20.
Sponsored by Universidad de Extremadura · Observational
This observational comparative study evaluates the surface electromyographic response of the gluteus maximus and biceps femoris during the Nordic Hamstring Exercise in adult male soccer players with a previous hamstring muscle injury.
Participants are classified according to their usual soccer discipline as 11-a-side soccer players or futsal players. All participants complete the same standardized Nordic Hamstring Exercise assessment during a single experimental session. Surface electromyography is recorded from the gluteus maximus and biceps femoris before, during, and immediately after the exercise protocol.
The main objective is to compare normalized electromyographic activation between soccer disciplines during the exercise, with particular attention to peak muscle activation across six valid Nordic Hamstring Exercise repetitions. Secondary analyses evaluate the immediate change in normalized muscle activation from pre-exercise to post-exercise.
Participants complete a single standardized assessment session. Baseline sociodemographic and anthropometric characteristics are recorded before testing. The Nordic Hamstring Exercise is performed from a kneeling position while an evaluator or training partner stabilizes the participant's ankles and lower legs. The participant maintains the trunk and thighs aligned and controls the forward descent primarily through eccentric hamstring action. The descent is paced at approximately 3 seconds. The hands and arms are used to arrest the fall and assist the return to the initial position in order to minimize concentric loading.
Six valid maximal-effort Nordic Hamstring Exercise repetitions are recorded, with recovery between repetitions. Surface electromyographic activity is collected throughout the assessment from the biceps femoris and gluteus maximus.
Surface electromyography is recorded using the mDurance® system (mDurance Solutions SL, Granada, Spain), based on a portable Shimmer3 EMG unit with two surface EMG channels, a sampling frequency of 1024 Hz, 24-bit signal resolution, and an overall amplification range of 100-10,000 V/V. The recorded signals are processed using the mDurance methodology, including a fourth-order Butterworth band-pass filter with cut-off frequencies of 20-450 Hz and root mean square smoothing with a 0.025-second window and 0.0125-second overlap. Skin preparation and electrode placement follow standardized surface electromyography procedures.
Electromyographic amplitude is normalized to a maximal voluntary isometric contraction reference and expressed as a percentage of MVIC (%MVIC). The main variables are the peak normalized RMS amplitude of the biceps femoris and gluteus maximus during the six repetitions, together with pre-exercise and immediately post-exercise normalized activation. Comparisons are performed between 11-a-side soccer and futsal players.
Universidad de Extremadura is the lead sponsor of 39 studies on the registry; 3 are open to participants now.
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The criteria were revised on the registry on Oct 20, 2026. See what changed
Male 11-a-side soccer and futsal players recruited by convenience sampling from two amateur sports clubs in Badajoz, Spain. Participants had a previous physician-diagnosed type 2b functional hamstring disorder affecting the dominant lower limb, occurring 1-12 months before assessment, and had returned to regular sporting activity without current pain or active injury.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Male 11-a-side soccer players with a previous type 2b hamstring injury who complete the same single-session Nordic Hamstring Exercise electromyographic assessment protocol as the futsal cohort.
Male futsal players with a previous type 2b hamstring injury who complete the same single-session Nordic Hamstring Exercise electromyographic assessment protocol as the 11-a-side soccer cohort.
Mean Peak Biceps Femoris Long Head sEMG Activity During the Nordic Hamstring Exercise
Mean peak normalized surface electromyographic (sEMG) activity of the biceps femoris long head during the Nordic hamstring exercise. The highest root mean square (RMS) amplitude recorded during each of the six repetitions was identified, and the six peak values were averaged to obtain a participant-level estimate. Results were expressed as a percentage of the maximal voluntary isometric contraction reference (%MVIC).
Time frame: During the single experimental session (six NHE repetitions).
Mean Peak Gluteus Maximus sEMG Activity During the Nordic Hamstring Exercise
Mean peak normalized surface electromyographic (sEMG) activity of the gluteus maximus during the Nordic hamstring exercise. The highest root mean square (RMS) amplitude recorded during each of the six repetitions was identified, and the six peak values were averaged to obtain a participant-level estimate. Results were expressed as a percentage of the maximal voluntary isometric contraction reference (%MVIC).
Time frame: During the single experimental session (six NHE repetitions).
Change in Resting Biceps Femoris Long Head sEMG Activity
Change in resting normalized surface electromyographic (sEMG) activity of the biceps femoris long head from immediately before to immediately after the Nordic hamstring exercise protocol. Resting activity was recorded for 10 seconds in a standardized prone position and quantified as the mean root mean square (RMS) amplitude over the central 5 seconds of each recording. The change was calculated as post-exercise minus pre-exercise activity and expressed as %MVIC.
Time frame: Immediately before and after the six-repetition NHE protocol, during a single experimental session.
Change in Resting Gluteus Maximus sEMG Activity
Change in resting normalized surface electromyographic (sEMG) activity of the gluteus maximus from immediately before to immediately after the Nordic hamstring exercise protocol. Resting activity was recorded for 10 seconds in a standardized prone position and quantified as the mean root mean square (RMS) amplitude over the central 5 seconds of each recording. The change was calculated as post-exercise minus pre-exercise activity and expressed as %MVIC.
Time frame: Immediately before and after the six-repetition NHE protocol, during a single experimental session.
Plan to share: No — Individual participant data are not planned for public sharing because of privacy and ethical restrictions.
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Ran from Jan 2026 to primary completion in Apr 2026, 3 months.
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This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Universidad de Extremadura