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Updated: Jul 17, 2026
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Isometric and Eccentric Force Generation Assessment of Skeletal Muscles Isolated from Murine Models of Muscular Dystrophies
Published on: January 31, 2013
Comparison of electromyographic activity during eccentrically versus concentrically loaded isometric contractions
John C Garner1, Troy Blackburn, Wendi Weimar
1Department of Health and Human Performance, Auburn University, 2050 Beard Eaves Memorial Coliseum, Auburn, AL 36849, United States. jcgarner@olemiss.edu
Summary
Maximal voluntary isometric contractions, whether concentric or eccentric, show similar electromyographic (EMG) amplitudes. This finding suggests both loading types are comparable for research and training purposes.
Area of Science:
- Biomechanics
- Exercise Physiology
- Neuroscience
Background:
- Electromyographic (EMG) amplitude correlates with mechanical tension during isometric contractions.
- Maximal voluntary isometric contractions are typically performed via concentric (resisting immovable object) or eccentric (resisting load) actions.
- Existing literature suggests higher EMG amplitude during concentric versus eccentric contractions of similar magnitude.
Purpose of the Study:
- To compare electromyographic (EMG) amplitudes under different loading configurations designed to elicit isometric muscle contraction.
- To investigate the effects of concentric and eccentric loading methods on EMG amplitude during isometric plantarflexion.
Main Methods:
- Twenty healthy volunteers performed maximal voluntary plantarflexion efforts.
- Surface EMG of the soleus and vertical ground reaction force (GRFv) were recorded.
- Participants completed isometric plantarflexion at 20-50% GRFv(max) under both concentric (immovable resistance) and eccentric (applied load resisting dorsiflexion) loading conditions.
Main Results:
- A significant main effect for loading level (20-50% GRFv(max)) on mean EMG amplitude was observed (p=0.007).
- No significant main effect for loading type (concentric vs. eccentric) was found.
- The interaction between loading type and loading level was also non-significant (p>0.05).
Conclusions:
- Isometric muscle contractions loaded in either a concentric or eccentric manner elicit similar EMG amplitudes.
- These findings indicate that concentric and eccentric loading methods are comparable for eliciting isometric muscle contractions in research settings.
- The study provides evidence supporting the use of both loading types for consistent EMG amplitude measurements during isometric exercises.
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