Relative proportion of vigorous physical activity, total volume of moderate to vigorous activity, and body mass index in youth: The Millennium Cohort Study

Background: The present physical activity guidelines suggest that when the overall activity energy expenditure is held constant, moderate and vigorous intensity activities (MVPA) provide equivalent health benefits. We explored associations between vigorous physical activity on body mass index whilst controlling for volume of MVPA. Methods: In a longitudinal study with 7 years follow-up (n = 4770; aged 7 years old at baseline), physical activity was measured objectively at baseline. Body mass index (BMI) was measured at baseline and follow-up. Vigorous activity was expressed as the percentage of total MVPA. Results: Participants in the highest vigorous activity tertile at baseline were at lower odds (odds ratio = 0.70; 95% CI: 0.55, 0.88) of overweight/obesity at follow-up compared with those in the lowest vigorous activity tertile after adjustment for total volume of MVPA, BMI at baseline, sex, ethnicity and social status. Conclusion: The results suggest vigorous activity, regardless of volume, is important in preventing excessive weight gain in young people.