Related Experiment Videos
Neuromuscular fatigue development during maximal concentric and isometric knee extensions
Nicolas Babault1, Kevin Desbrosses, Marie-Sophie Fabre
1Performance Motrice et Santé, Unité de Formation et de Recherche des Sciences et Techniques des Activités Physiques et Sportives, Université Marc Bloch, 14 rue René Descartes, 67084 Strasbourg Cedex, France. nbabault@umb.u-strasbg.fr
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 12, 2005
Summary
This study reveals that concentric exercises cause peripheral fatigue before central fatigue, while isometric exercises show the opposite pattern, impacting neuromuscular fatigue mechanisms differently. Both methods led to similar torque decreases.
Area of Science:
- Exercise Physiology
- Neuromuscular Physiology
Background:
- Understanding neuromuscular fatigue mechanisms is crucial for optimizing training and rehabilitation.
- Concentric and isometric contractions may induce fatigue through distinct pathways, influencing muscle performance and activation.
Purpose of the Study:
- To investigate and compare the mechanisms of neuromuscular fatigue during maximal concentric versus isometric leg extensions.
- To determine if similar torque decrements result in comparable central and peripheral fatigue markers.
Main Methods:
- Nine physically active men underwent two fatiguing protocols: isokinetic concentric (CON) and isometric (ISO) leg extensions.
- Measurements included maximal voluntary torque, muscle activation (twitch interpolation), electromyography (EMG), and evoked mechanical properties.
- Protocols were designed to achieve similar torque decrements across three series.
Main Results:
- Both CON and ISO protocols resulted in similar overall torque decrements and contraction durations.
- Peripheral fatigue (reduced doublet-twitch amplitude) was greater in early CON series compared to ISO.
- Central fatigue (reduced activation and EMG root mean square) was greater across all ISO series compared to CON.
Conclusions:
- Concentric and isometric fatiguing exercises elicit different neuromuscular fatigue patterns.
- Concentric exercise initially leads to peripheral fatigue, followed by central fatigue.
- Isometric exercise initially leads to central fatigue, followed by peripheral fatigue.