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Test-Retest Variability and Reliability of Volitional and Nonvolitional Assessments of Muscle Endurance in Healthy
Alan J Metcalfe1,2, Edward Mills1, Trudie Chalder3
1Centre for Human and Applied Physiological Sciences (CHAPS), Faculty of Life Sciences and Medicine, Denmark Hill Campus, King's College London, London, UNITED KINGDOM.
Medicine and Science in Sports and Exercise
|October 16, 2025
Summary
Muscle endurance testing using both volitional and non-volitional methods is reliable for handgrip and quadriceps. Non-volitional muscle endurance assessments are particularly useful for individuals unable to perform voluntary contractions.
Area of Science:
- Exercise Physiology
- Biomedical Engineering
Background:
- Muscle endurance assessment commonly relies on volitional contractions, which can be influenced by participant cooperation and motivation.
- Non-volitional techniques, utilizing direct muscle stimulation, offer a potential solution to the limitations of volitional methods.
Purpose of the Study:
- To evaluate the variability and reliability of both volitional and non-volitional techniques for assessing quadriceps and handgrip muscle endurance.
- To compare the performance of different muscle endurance measurement methods in healthy participants.
Main Methods:
- Fourteen healthy adults underwent three measurement sessions assessing handgrip and quadriceps strength (maximal voluntary contractions).
- Volitional endurance was measured via sustained handgrip at 50% maximal voluntary contraction and repeated quadriceps contractions at 60% maximal voluntary contraction.
- Non-volitional quadriceps endurance was assessed using transcutaneous electrical stimulation at 30% maximal voluntary contraction, measuring time to 70% force decline. Variability and reliability were quantified using coefficient of variation and intraclass correlation coefficients (ICC).
Main Results:
- Volitional handgrip endurance showed fair variability (20.5%) and good reliability (ICC=0.81).
- Volitional quadriceps endurance exhibited good variability (15.2%) and good reliability (ICC=0.76).
- Non-volitional quadriceps endurance demonstrated good variability (16.4%) and excellent reliability (ICC=0.92). Maximal voluntary contractions for both muscle groups showed good to very good variability and reliability.
Conclusions:
- Both volitional and non-volitional methods provide reliable measures of muscle endurance for the handgrip and quadriceps.
- Non-volitional muscle endurance testing may be a valuable tool for assessing individuals who cannot perform volitional maneuvers, such as certain patient populations.
