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Resistance training preserves skeletal muscle function during unloading in humans
Kimberley Schulze1, Philip Gallagher, Scott Trappe
1Human Performance Laboratory, Ball State University, Muncie IN 47306, USA.
Medicine and Science in Sports and Exercise
|February 6, 2002
Summary
Resistance training every third day during unloading effectively preserves knee extensor and plantar flexor muscle size and strength. This countermeasure strategy maintained muscle function despite 21 days of lower-limb suspension.
Area of Science:
- Exercise Physiology
- Muscle Physiology
- Biomedical Engineering
Background:
- Unloading, such as through lower-limb suspension, leads to significant muscle atrophy and strength loss.
- Preserving skeletal muscle mass and function during periods of reduced mechanical loading is crucial for recovery and performance.
Purpose of the Study:
- To design and evaluate a low-volume, high-intensity resistance-training program.
- To assess the program's effectiveness in preserving knee extensor (KE) and plantar flexor (PF) muscle size (cross-sectional area - CSA), strength, and neuromuscular function (integrated electromyography - IEMG) during unloading.
Main Methods:
- Thirty-two men were divided into four groups: ambulatory controls (AMB-CON), ambulatory with countermeasures (AMB-CM), unilateral lower-limb suspension controls (ULLS-CON), and ULLS with countermeasures (ULLS-CM).
- The ULLS-CM and AMB-CM groups performed resistance training every third day for 21 days.
- Muscle size (CSA), maximal voluntary contraction (MVC) strength, torque-velocity characteristics, and IEMG were measured.
Main Results:
- ULLS-CON showed a 7% decrease in KE and PF CSA and a 17% decrease in MVC strength.
- ULLS-CON exhibited significant declines in torque-velocity characteristics and altered IEMG activity.
- ULLS-CM maintained muscle size and strength, with some improvements in PF MVC and eccentric contractions, and preserved IEMG activity.
Conclusions:
- A resistance-training regimen performed every third day effectively counteracts muscle atrophy and strength loss caused by unloading.
- This training paradigm successfully maintained skeletal muscle size and both static and dynamic strength of the KE and PF during 21 days of unloading.