Multiple Shorter HIIT Sessions Are Better Than A Longer, Single Session, New Study Finds
A randomised crossover clinical trial.
This study, published in the European Journal of Sport Science in 2025 by Gilton de Jesus Gomes et al. investigates the effects of multiple shorter high-intensity interval exercise (HIIE) sessions spread throughout the day versus a single longer HIIE session on energy expenditure, cardiometabolic responses, and perceived exertion in middle-aged men.
Key Points
Aim
The study aimed to compare energy expenditure (EE), cardiometabolic, and perceptual responses during a single 21-minute HIIE session (1xHIIE) versus three shorter 7-minute HIIE sessions (3xHIIE) spaced 4 hours apart throughout the day. The hypotheses were that multiple shorter sessions would produce higher excess post-exercise oxygen consumption (EPOC) with lower cardiorespiratory strain and perceived exertion than a single session.
Methods
Design: Randomised crossover clinical trial.
Participants: 15 middle-aged (mean age 48.5 years) recreationally active men without cardiometabolic or orthopaedic conditions.
Protocols:
1x HIIE: One continuous 21-minute session.
3x HIIE: Three separate 7-minute sessions spaced 4 hours apart.
Measurements: Oxygen consumption (VO2), heart rate (HR), rate of perceived exertion (RPE), blood lactate, and energy expenditure during and after exercise.
Exercise intensity was set at 90% of maximal power output determined by prior VO2max testing on a cycle ergometer.
Results
Total energy expenditure during exercise was similar between protocols (approximately 298 kcal for 1xHIIE and 299 kcal for 3xHIIE; p=0.88).
Post-exercise energy expenditure (EPOC) was significantly higher after the 3x HIIE protocol, nearly double that of the single session (63 kcal vs. 27 kcal; p<0.001), adding about 36 kcal more total energy expenditure.
The cardiometabolic strain was lower in the 3x HIIE sessions, with reduced average heart rate (147 bpm vs. 158 bpm; p=0.018), lower blood lactate levels (5.4 mmol/L vs. 7.7 mmol/L; p=0.013), and reduced perceived exertion (RPE 14.4 vs. 15.8; p=0.0012).
These findings indicate that spreading exercise into multiple short bouts increases overall energy expenditure with less cardiovascular and perceptual strain.
Practical Takeaways
Splitting high-intensity interval training into multiple short sessions throughout the day can increase total daily energy expenditure more effectively than a single longer session.
Multiple short sessions are perceived as less strenuous and cause lower heart rate and lactate accumulation, which may enhance exercise adherence by reducing discomfort.
This approach can be a time-efficient and manageable strategy to interrupt sedentary behaviour and improve cardiometabolic health, especially for middle-aged individuals.
Implementing “exercise snacks” of brief high-intensity bouts could be integrated into daily routines at home or work, making it easier to meet physical activity recommendations.
Related
Key Takeaways
Multiple shorter HIIE sessions produce similar immediate energy expenditure but significantly greater post-exercise energy expenditure compared to a single session.
Cardiometabolic stress and perceived exertion are lower with multiple short sessions.
This exercise strategy may improve adherence and provide superior metabolic benefits for middle-aged adults.
The study supports the use of accumulated short bouts of high-intensity exercise as a viable alternative to traditional longer sessions for health and fitness improvements.
This research provides strong evidence that breaking up exercise into shorter, high-intensity segments throughout the day is an effective and less taxing method to increase energy expenditure and potentially improve health outcomes in middle-aged men.
Reference
Gomes, J., Diniz Magalhães, C. O., Queiroz, I. P., Chaves Garcia, B. C., Pereira, S., Moreira Costa, J. M., Cassilhas, R. C., Villela, D. C., Gripp, F., Amorim, F. T., & Dias-Peixoto, M. F. (2025). Multiple Shorter High-Intensity Interval Exercise Sessions During the Day Result in Greater Energy Expenditure With Less Exertion Than a Longer Single Session: A Randomized Crossover Clinical Trial. European Journal of Sport Science, 25(5), e12302. https://doi.org/10.1002/ejsc.12302