Physical activity fluctuations and body fat during adolescence

Pediatr Obes. 2012 Feb;7(1):73-81. doi: 10.1111/j.2047-6310.2011.00010.x. Epub 2011 Dec 1.


Objective: The objective of the study was to test the hypothesis that greater fluctuations in physical activity lead to greater increases in body fat during adolescence.

Methods: Seven hundred fifty-six adolescents in Montreal, Canada, aged 12-13 years at baseline, completed a 7-d physical activity recall questionnaire every 3 months over 5 years. Body mass index (BMI), waist circumference, and triceps and subscapular skinfold thickness were measured at baseline and at the end of follow-up. Subject-specific linear regressions, expressing physical activity as a function of time, were fitted and physical activity fluctuation scores were obtained by averaging the absolute values of regression residuals. The association between body fat after 5 years and the physical activity fluctuation score was assessed in linear regressions adjusting for baseline body fat, average number of physical activity sessions per week, diet and sociodemographic variables.

Results: Among boys, there were statistically significant positive associations between physical activity fluctuation and BMI (β, 95% confidence interval: 0.12, 0.02-0.21) and triceps skinfold (0.40, 0.17-0.63). The associations with waist circumference or subscapular skinfold were not statistically significant (0.22, -0.04-0.49; 0.13, -0.05-0.32, respectively). In girls, there were statistically significant negative associations between physical activity fluctuation and BMI (-0.12, -0.20 to -0.03), waist circumference (-0.54, -0.91 to -0.17), subscapular skinfold (-0.41, -0.56 to -0.26) and triceps skinfold (-0.22, -0.38 to -0.05).

Conclusion: Physical activity fluctuations appear to affect body fat during adolescence. Sex-specific interventions may be needed given that greater physical activity fluctuations seem unfavourable for boys and beneficial for girls.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / growth & development
  • Adipose Tissue / metabolism*
  • Adolescent
  • Body Composition / physiology
  • Body Mass Index*
  • Cohort Studies
  • Exercise / physiology*
  • Female
  • Follow-Up Studies
  • Humans
  • Linear Models
  • Longitudinal Studies
  • Male
  • Sex Factors
  • Skinfold Thickness
  • Waist Circumference