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Updated: May 29, 2026
14:02
Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Adjustments in motor unit properties during fatiguing contractions after training
Carolina Vila-Chã1, Deborah Falla, Miguel Velhote Correia
1Polytechnic Institute of Bragança, Bragança, Portugal.
Medicine and Science in Sports and Exercise
|September 10, 2011
Summary
Six weeks of training altered muscle fiber electrophysiology. Endurance training slowed the decline in motor unit conduction velocity during fatiguing contractions more than strength training.
Area of Science:
- Exercise Physiology
- Muscle Physiology
- Motor Control
Background:
- Muscle fiber membrane properties and motor unit discharge rates are crucial for sustained contractions.
- Understanding how different training modalities affect these properties is important for optimizing physical performance and rehabilitation.
Purpose of the Study:
- To investigate the effects of short-term strength and endurance training on muscle fiber membrane properties and motor unit discharge rates.
- To compare the impact of strength versus endurance training on vasti muscles during fatiguing contractions.
Main Methods:
- Twenty-five healthy sedentary men were divided into strength training, endurance training, or control groups for 6 weeks.
- Motor unit conduction velocity and EMG amplitude were measured during isometric knee extensions at 10% and 30% maximal voluntary contraction before and after training.
Main Results:
- Training slowed the rate of decline in motor unit conduction velocity at 30% maximal voluntary contraction.
- Endurance training resulted in a slower rate of decrease in motor unit conduction velocity compared to strength training.
- Motor unit discharge rates declined during sustained contractions, unaffected by training.
Conclusions:
- Short-term strength and endurance training alter muscle fiber electrophysiological properties.
- Endurance training demonstrates a superior effect in preserving motor unit conduction velocity during fatiguing contractions compared to strength training.
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