Objectives To evaluate effects of active bike commuting or leisure-time exercise of two intensities on peripheral insulin sensitivity (primary outcome), cardiorespiratory fitness and intra-abdominal adipose tissue mass (secondary outcomes).
Methods 188 physically inactive, healthy women and men (20-45 years) with overweight or class 1 obesity were recruited. In the 6-month trial, 130 participants were randomised to either: no intervention (CON), active commuting (BIKE) or leisure-time exercise of moderate (MOD, 50% VO2peak) or vigorous (VIG, 70% VO2peak) intensity. 100 completed follow-up testing. Exercise prescription was 5 days/week with a weekly exercise energy expenditure of 1600 kcal for women and 2100 kcal for men. Testing was performed at baseline, 3 months and 6 months.
Results Peripheral insulin sensitivity (ml/min/pmol insulin/L) increased (improved) by 24% (95% CI 6% to 46%, p=0.01) in VIG compared with CON at 3 months. Peripheral insulin sensitivity increased (improved) by 20% in BIKE (95% CI 1% to 43%, p=0.04) and 26% in VIG (95% CI 7% to 47%, p<0.01) compared with CON at 6 months. Cardiorespiratory fitness increased in all exercise groups compared with CON at 6 months; but the increase was higher in those that undertook vigorous exercise than those who did moderate exercise. Intra-abdominal adipose tissue mass diminished across all exercise groups in comparison to CON at 6 months.
Conclusions Active bike commuting improved cardiometabolic health; as did leisure-time exercise. Leisure-time exercise of vigorous intensity conferred more rapid effects on peripheral insulin sensitivity as well as additional effects on cardiorespiratory fitness than did moderate intensity exercise.
Trial registration NCT01962259
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MBB and MR contributed equally.
Contributors MBB, MR, ASG, JSQ and BMS designed and planned the study. MBB, MR, ASG, MT and JSQ performed data collection. MBB, MRLand ANC performed the data analysis. MBB and MR wrote the first draft of the paper and all other authors contributed with intellectual contributions and critical revisions. The final manuscript was read and approved by all authors.
Funding The work is carried out as a part of the research program ‘Governing Obesity’ funded by the University of Copenhagen’s Excellence Programme for Interdisciplinary Research http://go.ku.dk. Additional funding was provided by the Faculty of Health and Medical Sciences, University of Copenhagen, TrygFonden (grant number 1081289) and Gerda and Aage Haensch’s Fond.
Competing interests The guarantors (MBB, MR and BMS) affirm that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
Ethics approval The study was approved by the ethical committee of the Capital Region of Denmark (H-4-2013-108) and registered at the Danish Data Protection Agency.
Provenance and peer review Not commissioned; externally peer reviewed.