When Moderate Becomes Unpleasant and Intense Is Manageable: Exercise Intensity and Duration Interact to Regulate
Daniel J Kinghorn1, Matthew Hutchinson1, Sinead Curry2
1Faculty of Health Sciences and Sport, University of Stirling, Stirling, United Kingdom.
Journal of Sport & Exercise Psychology
|January 22, 2026
Summary
High-intensity exercise can decrease enjoyment, but brief, intense intervals like reduced-exertion high-intensity interval training (REHIT) paradoxically improve it. This study found REHIT offers greater remembered enjoyment and preference due to its short duration.
Area of Science:
- Exercise Physiology
- Sports Science
- Affective Responses to Exercise
Background:
- Higher intensity exercise is often linked to decreased affective valence, potentially reducing enjoyment and adherence.
- Findings suggest high-intensity interval training (HIIT) and sprint interval training (SIT) may be more enjoyable than moderate-intensity continuous training, presenting a paradox.
- An Intensity × Duration interaction effect is hypothesized to explain this paradox.
Purpose of the Study:
- To investigate the Intensity × Duration interaction effect on affective valence during different exercise intensities and durations.
- To compare affective valence changes and remembered enjoyment across various high-intensity training protocols.
- To determine exercise preferences following different high-intensity exercise interventions.
Main Methods:
- Twenty-nine participants completed five cycling sessions: 30 min at 80%, 100%, or 110% of ventilatory threshold (VT), SIT (22 min with 4x30s sprints), and REHIT (10 min with 2x20s sprints).
- Affective valence was measured during exercise, and remembered enjoyment was assessed post-exercise using the Physical Activity Enjoyment Scale.
- Participant preference for exercise protocols was recorded.
Main Results:
- Decreases in affective valence accelerated with higher intensities, but shorter sprint durations attenuated the overall drop.
- Reduced-exertion high-intensity interval training (REHIT) showed significantly less decrease in affective valence compared to SIT and 110% VT.
- REHIT resulted in higher remembered enjoyment and was preferred by 72% of participants compared to other high-intensity protocols.
Conclusions:
- Evidence supports an Intensity × Duration interaction effect influencing affective valence during exercise.
- The brief duration of supramaximal sprints in protocols like REHIT mitigates negative affective responses, explaining the paradoxical enjoyment of high-intensity training.
- REHIT emerges as a potentially more enjoyable and preferred high-intensity exercise modality due to its favorable affect-duration profile.
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