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Related Experiment Video

Updated: Jun 9, 2025

Muscle Imbalances: Testing and Training Functional Eccentric Hamstring Strength in Athletic Populations

Muscle Imbalances: Testing and Training Functional Eccentric Hamstring Strength in Athletic Populations

Published on: May 1, 2018

Multiscale hamstring muscle adaptations following 9 weeks of eccentric training.

Max H Andrews¹, Anoosha Pai S², Reed D Gurchiek³

¹School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD 4072, Australia; Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.

Journal of Sport and Health Science

|October 26, 2024

Summary

This summary is machine-generated.

Nordic hamstring exercise (NHE) training increases hamstring muscle fascicle length and strength by adding sarcomeres in series. These adaptations partially reverse after detraining, highlighting the importance of continued eccentric training for muscle health.

Keywords:

Adaptation Muscle architecture Nordic hamstring exercise

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Area of Science:

Muscle physiology
Sports science
Biomechanics

Background:

Eccentric training, like Nordic hamstring exercise (NHE), is used for hamstring strain prevention.
Previous research suggested muscle fascicle lengthening and sarcomere addition, but direct measurement in humans was limited.
This study investigated multiscale hamstring muscle adaptations to NHE training and subsequent detraining.

Purpose of the Study:

To measure hamstring muscle adaptations at the fascicle and sarcomere level in response to NHE training.
To assess changes in muscle volume and eccentric strength.
To evaluate the reversibility of these adaptations during a detraining period.

Main Methods:

Twelve participants underwent 9 weeks of supervised NHE training followed by 3 weeks of detraining.
Biceps femoris long-head (BFlh) muscle fascicle length, sarcomere length, and serial sarcomere number were measured.
Muscle volume and eccentric knee flexion strength were assessed at baseline, post-training, and post-detraining.

Main Results:

NHE training significantly increased BFlh fascicle length (up to 33% distally) and serial sarcomere number (up to 49% distally).
Muscle volume increased by 8% and eccentric strength by 40% post-training.
Detraining led to decreases in fascicle length and serial sarcomere number.

Conclusions:

Nine weeks of NHE training induced significant, region-specific increases in BFlh muscle fascicle length, volume, and force production.
Direct measurement confirmed that increased fascicle length resulted from the addition of sarcomeres in series.
These findings elucidate the mechanisms of eccentric exercise adaptation in human skeletal muscle.