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Related Experiment Video

Updated: May 19, 2026

Induction and Assessment of Exertional Skeletal Muscle Damage in Humans

Induction and Assessment of Exertional Skeletal Muscle Damage in Humans

Published on: December 11, 2016

Preferential type II muscle fiber damage from plyometric exercise.

Filippo Macaluso¹, Ashwin W Isaacs, Kathryn H Myburgh

¹Department of Physiological Sciences, Stellenbosch University, South Africa. filippo.macaluso@unipa.it

Journal of Athletic Training

|August 15, 2012

Summary

Plyometric exercise primarily damages fast-twitch muscle fibers, specifically type IIa and IIx. This study provides direct evidence of skeletal muscle fiber type susceptibility to acute plyometric training.

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Intact Short, Intermediate, and Long Skeletal Muscle Fibers Obtained by Enzymatic Dissociation of Six Hindlimb Muscles of Mice: Beyond Flexor Digitorum Brevis

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Area of Science:

Exercise Physiology
Muscle Biology
Sports Science

Background:

Plyometric training is widely used in sports.
Research on plyometric training's effects on muscle morphology is limited and yields conflicting results.
The specific muscle fiber types affected by plyometric exercise remain unclear.

Purpose of the Study:

To investigate skeletal muscle structural and ultrastructural changes after acute plyometric exercise.
To identify the predominant muscle fiber type damaged by plyometric exercise.

Main Methods:

A descriptive laboratory study involving eight healthy, untrained individuals.
Participants performed an acute plyometric exercise bout (10 sets of 10 squat-jumps).
Muscle biopsies and blood samples were analyzed for muscle damage and creatine kinase activity using microscopy and biochemical assays.

Main Results:

Creatine kinase levels peaked one day post-exercise, indicating muscle damage.
Immunofluorescence showed sarcolemmal damage predominantly in fast-twitch fibers (type IIa and IIx).
Electron microscopy confirmed significant sarcomere damage, predominantly in type II muscle fibers (86% glycolytic, 84% oxidative) compared to type I fibers (27%).

Conclusions:

A single session of plyometric exercise predominantly impacts type II muscle fibers.
This finding clarifies the susceptibility of different muscle fiber types to plyometric stimuli.