Related Experiment Videos
Variability of time to exhaustion during submaximal exercise
T M McLellan1, S S Cheung, I Jacobs
1Environmental Physiology Section, Defence and Civil Institute of Environmental Medicine, North York, Ontario.
Summary
Exercise time to exhaustion (TE) shows significant variability among individuals during submaximal exercise. This variability means TE alone is insufficient for evaluating training or supplement effectiveness in males with average fitness.
Area of Science:
- Exercise Physiology
- Sports Science
- Human Performance
Background:
- Time to exhaustion (TE) is a common metric for assessing interventions like endurance training and nutritional supplements.
- Understanding the variability of TE is crucial for accurate interpretation of study results.
Purpose of the Study:
- To determine the variability of time to exhaustion (TE) during submaximal exercise at 80% VO2max in males.
- To assess the impact of individual variability on the reliability of TE as an outcome measure.
Main Methods:
- Fifteen healthy males performed cycle ergometry to exhaustion at 80% VO2max on five separate occasions.
- Individual variability in TE was quantified using coefficients of variation (CV).
- Subjects were grouped into low and high CV groups based on their TE variability.
Main Results:
- Substantial inter-subject variability in TE was observed, with CVs ranging from 2.8% to 31.4%.
- The low CV group showed significant increases in TE by Test 3, while the high CV group demonstrated increased TE by Test 5.
- Variability in physiological measures (VO2, VE, pH, Pco2, rectal temperature) was low (<5%) and did not differ between groups.
Conclusions:
- Significant individual variability in time to exhaustion exists during repeated submaximal exercise bouts in males.
- TE alone may not be a reliable sole dependent measure for evaluating treatment effects due to this variability.
- Larger sample sizes or alternative outcome measures may be necessary to reliably detect treatment effects in similar populations.