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Updated: Nov 14, 2025
08:27
A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement
Published on: February 22, 2022
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Exploring Differences in Cardiorespiratory Fitness Response Rates Across Varying Doses of Exercise Training: A
Jacob T Bonafiglia1, Nicholas Preobrazenski1, Hashim Islam1
1School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada.
Sports Medicine (Auckland, N.Z.)
|March 11, 2021
Summary
Higher exercise training doses increase cardiorespiratory fitness (CRF) response rates primarily through larger average improvements, not by reducing individual variability. This suggests dose-dependent improvements in CRF are driven by mean effects.
Area of Science:
- Exercise physiology
- Cardiorespiratory fitness research
- Clinical trial analysis
Background:
- Cardiorespiratory fitness (CRF) improvements from exercise training vary significantly among individuals.
- Understanding factors influencing CRF response rates, such as exercise dose and individual variability, is crucial for optimizing training prescriptions.
Purpose of the Study:
- To investigate whether greater mean changes in cardiorespiratory fitness (CRF) or reduced interindividual variability explain higher CRF response rates with increased exercise training doses.
- To test the hypothesis that higher exercise doses lead to better CRF outcomes.
Main Methods:
- Retrospective analysis of CRF data from eight randomized controlled trials (RCTs) involving 1590 participants.
- Calculation of CRF response rates based on individual confidence intervals (CIs) exceeding 0.5 metabolic equivalents (METs).
- Comparison of CRF response rates, mean changes, and interindividual variability across different exercise training doses within RCTs.
Main Results:
- Higher exercise training doses consistently resulted in larger CRF response rates compared to lower doses.
- In most cases (7/8), higher doses led to greater mean CRF changes with similar interindividual variability.
- Similar CRF response rates between exercise groups correlated with similar mean CRF changes.
Conclusions:
- Increased CRF response rates with higher exercise doses are primarily driven by larger average improvements in CRF.
- Interindividual variability in CRF response does not appear to be significantly reduced by higher exercise doses.
- The proportion of individuals improving CRF beyond a 0.5 MET threshold is independent of response heterogeneity for a given exercise dose.
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