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Updated: Jun 2, 2026
08:27
A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement
Published on: February 22, 2022
Physiological responses during interval training with different intensities and duration of exercise
Jorge M Zuniga1, Kris Berg, John Noble
1Human Performance Laboratory, Department of Nutrition and Health Sciences, Center of Youth Fitness and Sports Research, University of Nebraska Lincoln, Lincoln, Nebraska, USA. jzuniga2@unlserve.unl.edu
Journal of Strength and Conditioning Research
|April 28, 2011
Summary
Shorter interval training (IT) sessions, specifically 30-second intervals at 90% maximum power output (MPO), enhance total exercise volume and metabolic demand (VO₂). This approach leads to greater total VO₂ and lower blood-lactate concentration (BLC) compared to longer intervals or higher intensities.
Area of Science:
- Exercise Physiology
- Sports Science
- Human Performance
Background:
- Interval training (IT) is a common method for improving athletic performance.
- Optimizing IT protocols requires understanding the interplay between exercise intensity, duration, and physiological responses.
- Key performance indicators include maximal oxygen uptake (VO₂), total energy expenditure, and fatigue markers like blood-lactate concentration (BLC).
Purpose of the Study:
- To compare four interval training (IT) protocols with varying exercise intensities (90% and 100% maximum power output [MPO]) and durations (30 seconds and 3 minutes).
- To determine the effects of these IT protocols on mean and total VO₂, duration of exertion at ≥95% MPO, blood-lactate concentration (BLC), and rating of perceived exertion.
- To provide evidence-based recommendations for selecting optimal IT protocols to maximize training adaptations.
Main Methods:
- Twelve recreationally competitive triathletes (7 male, 5 female) participated in the study.
- Subjects performed four distinct IT sessions on a cycle ergometer, manipulating exercise intensity and duration.
- Physiological variables including VO₂, heart rate (HR), BLC, and rating of perceived exertion were measured during and after each session.
Main Results:
- Interval training using 30-second intervals (30-30 seconds) resulted in longer session durations, higher total and mean VO₂, and lower BLC compared to 3-minute intervals.
- Submaximal intensity exercise at 90% MPO allowed for longer training sessions and higher total VO₂ compared to 100% MPO intensity.
- Exertion at ≥95% MPO was significantly longer with the 30-second interval protocol.
Conclusions:
- For enhancing total exercise time at high intensity and overall VO₂ within a single session, IT protocols with short durations (30 seconds) and submaximal intensities (90% MPO) are recommended.
- Short-duration intervals may enable athletes to complete longer IT sessions, leading to greater metabolic demands (VO₂) and reduced BLC compared to longer intervals.
- These findings suggest that manipulating interval duration and intensity can effectively modulate training stress and potential adaptations in endurance athletes.
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