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Updated: May 9, 2026
A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement
Published on: February 22, 2022
Sex-specific responses to self-paced, high-intensity interval training with variable recovery periods
C Matthew Laurent1, Lauren S Vervaecke, Matthew R Kutz
11School of Human Movement, Sport, and Leisure Studies, Bowling Green State University, Bowling Green, Ohio; 2Division of Applied Physiology, University of South Carolina, Columbia, South Carolina; and 3Department of Health, Physical Education, and Recreation, University of North Alabama, Florence, Alabama.
Men and women exhibit distinct physiological responses during self-paced high-intensity interval training (HIIT). Women experience greater cardiovascular strain at self-selected intensities, suggesting enhanced recovery during HIIT.
Area of Science:
- Exercise Physiology
- Sports Science
- Human Performance
Background:
- High-intensity interval training (HIIT) is a popular training modality.
- Understanding sex-specific responses to self-paced HIIT is crucial for optimizing training protocols.
- Previous research has not fully elucidated the physiological differences between men and women during self-selected intensity HIIT.
Purpose of the Study:
- To investigate sex-specific physiological and perceptual responses during self-paced treadmill HIIT.
- To compare intensity, cardiovascular strain, and recovery between men and women during HIIT.
- To determine the optimal work-to-rest ratio for HIIT based on sex-specific responses.
Main Methods:
- Sixteen participants (8 men, 8 women) completed a VO2peak test and three HIIT sessions with varying recovery intervals (1, 2, or 4 minutes).
- Intensity was measured using percentage of velocity at VO2peak (%vVO2peak), %VO2peak, and %HRmax.
- Blood lactate concentration ([La]) and ratings of perceived exertion (RPE) were recorded throughout the sessions.
Main Results:
- Significant sex differences were observed in %vVO2peak and %HRmax.
- Men self-selected higher %vVO2peak (84.5% vs. 80.7%), while women exhibited higher %HRmax (96.9% vs. 92.1%) and %VO2peak (89.6% vs. 86.1%).
- No significant differences were found in [La] or perceptual responses between sexes.
Conclusions:
- Women may experience improved recovery during high-intensity exercise due to self-selected intensities eliciting greater cardiovascular strain.
- The findings support a 2:1 work-to-rest ratio as optimal for both men and women during HIIT.
- Sex-specific considerations may be necessary for tailoring effective HIIT programs.
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