Cardiorespiratory fitness and accelerometer-determined physical activity following one year of free-living high-intensity interval training and moderate-intensity continuous training: a randomized trial.

M E Jung, S R Locke, J E Bourne, M R Beauchamp, T Lee, J Singer, M MacPherson, J Barry, C Jones, J P Little

Journal: The international journal of behavioral nutrition and physical activity 2020;17(1):25

PMID: 32102667

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Plain Language Summary

High-intensity interval training (HIIT), is considered an effective and time-efficient type of exercise and has been shown to improve cardiorespiratory fitness (CRF). However, little is known about long term adherence and effectiveness. The aim of this randomized trial was to compare the effects of HIIT and moderate intensity continuous training (MICT) in people with obesity or overweight and low activity levels. 99 participants were randomly assigned to HIIT (75 minutes per week) or MICT (150 minutes per week) and received a two-week exercise counselling programme including behaviour change techniques. Participants tracked their exercise for 12 months using a mobile application. Both groups experienced significant improvements in CRF, body fat and waist circumference over the 12 months study, with no differences between groups. Both groups increased their weekly exercise time, but the MCIT group increased exercise time significantly more than the HIIT group (by 33 minutes more). The authors concluded that although participants in the MCIT group spent double as much time exercising than the HIIT group, there were no differences in the health benefits after one year.

Abstract

BACKGROUND

Free-living adherence to high-intensity interval training (HIIT) has not been adequately tested. This randomized trial examined changes in cardiorespiratory fitness (CRF) and accelerometer-measured purposeful physical activity over 12 months of free-living HIIT versus moderate-intensity continuous training (MICT).

METHODS

Ninety-nine previously low-active participants with overweight/obesity were randomly assigned to HIIT (n = 47) or MICT (n = 52). Both interventions were combined with evidence-based behaviour change counselling consisting of 7 sessions over 2 weeks. Individuals in HIIT were prescribed 10 X 1-min interval-based exercise 3 times per week (totalling 75 min) whereas individuals in MICT were prescribed 150 min of steady-state exercise per week (50 mins 3 times per week). Using a maximal cycling test to exhaustion with expired gas analyses, CRF was assessed at baseline and after 6 and 12 months of free-living exercise. Moderate-to-vigorous physical activity of 10+ minutes (MVPA10+) was assessed by 7-day accelerometry at baseline, 3, 6, 9, and 12 months. Intention to treat analyses were conducted using linear mixed models.

RESULTS

CRF was improved over the 12 months relative to baseline in both HIIT (+ 0.15 l/min, 95% CI 0.08 to 0.23) and MICT (+ 0.11 l/min, 95% CI 0.05 to 0.18). Both groups improved 12-month MVPA10+ above baseline (HIIT: + 36 min/week, 95% CI 17 to 54; MICT: + 69 min/week, 95% CI 49 to 89) with the increase being greater (by 33 min, 95% CI 6 to 60) in MICT (between group difference, P = 0.018).

CONCLUSION

Despite being prescribed twice as many minutes of exercise and accumulating significantly more purposeful exercise, CRF improvements were similar across 12 months of free-living HIIT and MICT in previously low-active individuals with overweight/obesity.

Address: School of Health and Exercise Sciences Faculty of Health and Social Development, The University of British Columbia Okanagan, FHSD 3333 University Way ART360, Kelowna, BC, V1V 1V7, Canada. [email protected].; School of Health and Exercise Sciences Faculty of Health and Social Development, The University of British Columbia Okanagan, FHSD 3333 University Way ART360, Kelowna, BC, V1V 1V7, Canada.; The University of Bristol, Bristol, UK.; The University of British Columbia, Vancouver Campus, Vancouver, Canada.

DOI: 10.1186/s12966-020-00933-8