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Induction and Assessment of Exertional Skeletal Muscle Damage in Humans
Published on: December 11, 2016
Attenuation of eccentric exercise-induced muscle damage by preconditioning exercises
Trevor Chung-Ching Chen1, Hsin-Lian Chen, Alan J Pearce
1Department of Physical Education, National Chiayi University, Chiayi County, Taiwan. trevorchen@mail.ncyu.edu.tw
Medicine and Science in Sports and Exercise
|June 13, 2012
Summary
Low-intensity eccentric contractions (ECCs) and isometric contractions (ISOs) can protect muscles from damage. However, a threshold intensity is needed for ECCs, while ISOs at longer muscle lengths offer a preconditioning effect.
Area of Science:
- Exercise Physiology
- Muscle Physiology
- Sports Science
Background:
- Muscle damage can result from eccentric contractions (ECCs).
- Preconditioning may mitigate exercise-induced muscle damage.
- Understanding optimal preconditioning protocols is crucial for training and rehabilitation.
Purpose of the Study:
- To compare the protective effects of initial low-intensity eccentric contractions (ECCs) versus maximal isometric contractions (ISOs) against subsequent maximal eccentric contraction (MaxECC)-induced muscle damage.
- To investigate the influence of contraction intensity and muscle length on the protective preconditioning effect.
Main Methods:
- Untrained young men were divided into five groups: MaxECC, 10% ECC, 20% ECC, 90° ISO, and 20° ISO.
- Initial bouts involved 30 contractions (ECCs or ISOs) at specific intensities or joint angles.
- Three weeks later, all subjects performed 30 MaxECCs, and various physiological measures were assessed before and after both bouts.
Main Results:
- All tested preconditioning protocols (10% ECC, 20% ECC, 90° ISO, 20° ISO) reduced muscle damage markers compared to a single MaxECC bout.
- Lower intensity ECCs (10% and 20%) and 90° ISOs showed greater protection than 20° ISOs and 20% ECCs after the initial bout.
- After the second bout, 20% ECC and 20° ISO groups showed reduced damage, with 20° ISO exhibiting a greater protective effect, though less than MaxECC.
Conclusions:
- A threshold intensity exists for eccentric contractions to provide a protective preconditioning effect.
- Isometric contractions performed at longer muscle lengths (e.g., 20° ISO) can induce a significant preconditioning effect against muscle damage.
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