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Related Experiment Video

Updated: Sep 15, 2025

Muscle Imbalances: Testing and Training Functional Eccentric Hamstring Strength in Athletic Populations
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The Time-Course of Hamstring Muscle Passive Stiffness and Perceived Tightness After Strenuous Exercise: Is It Time to

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|July 15, 2025
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Summary

Postexercise hamstring muscle stiffness, measured objectively with shear wave elastography (SWE), does not correlate with perceived tightness. Athletes

Keywords:
hamstring muscle stiffnessprone leg curl exerciseshear wave elastography

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Area of Science:

  • Sports Medicine
  • Exercise Physiology
  • Biomechanical Analysis

Background:

  • Hamstring injuries are common in high-speed running sports, with postexercise muscle stiffness considered a potential risk factor.
  • Objective measurement tools for monitoring the time-course of postexercise muscle stiffness were previously lacking.
  • Shear wave elastography (SWE) offers an objective method for assessing tissue stiffness.

Purpose of the Study:

  • To determine and compare the time-course of localized passive stiffness in hamstring muscles using SWE.
  • To compare this objective stiffness measurement with the subjective perception of hamstring tightness after exhaustive exercise.

Main Methods:

  • Twenty-four subjects performed a prone-leg-curl exercise to exhaustion.
  • Passive hamstring muscle stiffness was quantified using SWE at multiple time points (baseline, 0, 24, 48, 72, 96 hours postexercise).
  • Perceived hamstring tightness was assessed using a numeric rating scale at the same time points.

Main Results:

  • No significant changes in passive stiffness were observed in the semimembranosus and biceps femoris long head muscles over time.
  • The semitendinosus muscle showed a significant increase in shear modulus, peaking at 48 hours postexercise (+9.7%), followed by a decrease.
  • Perceived hamstring tightness peaked at 24 hours postexercise and normalized by 96 hours, showing a different time-course than localized stiffness.

Conclusions:

  • The time-course of perceived hamstring tightness after strenuous exercise does not align with localized hamstring passive stiffness measurements.
  • Objective stiffness measurements (SWE) and subjective tightness perception may not be directly comparable in the postexercise recovery period.
  • Caution is advised when designing training and recovery programs based solely on perceived tightness, highlighting the need for objective measures.