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Updated: Jun 24, 2026
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Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Low-frequency fatigue at maximal and submaximal muscle contractions
R R Baptista1, E M Scheeren, B R Macintosh
1Escola de Educação Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
Summary
Low-frequency fatigue (LFF) selectively impairs muscle force after repetitive contractions. This study found LFF occurred after submaximal concentric, but not eccentric, knee extensions, especially after 1-hour recovery.
Area of Science:
- Exercise Physiology
- Muscle Physiology
- Sports Science
Background:
- Repetitive muscle contractions can lead to reduced force production, particularly when stimulated at low frequencies.
- This phenomenon, known as low-frequency fatigue (LFF), is a selective impairment in skeletal muscle force generation.
- The influence of contraction type (concentric vs. eccentric) on LFF development is not fully understood.
Purpose of the Study:
- To investigate and compare low-frequency fatigue (LFF) following maximal and submaximal concentric and eccentric knee extensor contractions.
- To determine the impact of contraction intensity and type on the development and recovery of LFF.
Main Methods:
- Ten healthy males performed maximal voluntary contractions and a fatigue protocol involving 60 maximal or submaximal concentric or eccentric knee extensions.
- Low-frequency fatigue (LFF) was assessed by measuring isometric torque at low (20 Hz) and high (100 Hz) stimulation frequencies before, immediately after, and 1 hour after exercise.
- The ratio of 20 Hz to 100 Hz torque was calculated to quantify LFF.
Main Results:
- Low-frequency fatigue (LFF) was observed after 1-hour recovery in all tested conditions except for submaximal eccentric contractions.
- LFF was not present immediately after exercise, irrespective of contraction intensity or type.
- Submaximal concentric contractions induced LFF, whereas submaximal eccentric contractions did not, with LFF being more pronounced after a 1-hour recovery period.
Conclusions:
- Submaximal eccentric contractions appear to resist the development of low-frequency fatigue (LFF) compared to submaximal concentric contractions.
- The recovery period of 1 hour significantly influences the manifestation of LFF, suggesting a delayed onset or incomplete recovery.
- Contraction type is a critical factor modulating the susceptibility to LFF in skeletal muscle.
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