The effects of vigorous activity on body composition – results from a UK-based population study among women
Title: Physical Activity in relation to body size and composition in women in UK Biobank
Authors: Guo, W., Bradbury, K. Reeves, G. and Key, T.
Journal: Annals of Epidemiology
Date: 2014
Impact Factor: 2.8
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Why they did it?
Physical Activity (PA) is undertaken at various intensities; light (slow walking), moderate (brisk walking) and vigorous (jogging). There is strong evidence that shows that those who undertake higher levels of PA have a more favourable body composition (e.g. lower levels of body fat, Body Mass Index [BMI], and waist circumference) than those who undertaken lower levels of PA. This is important because having a high BMI, waist circumference and level of body fat is associated with a variety of chronic disease risks. To date, studies examining the relationship between PA and body composition have typically combined PA intensities to broadly categorise individuals as either active or not active. Few studies have specifically looked at the contribution of PA intensities on body composition. For example, whether vigorous-intensity activity (VPA) or moderate-intensity activity (MPA) have a greater impact on body composition. Moreover, few studies have examined this amongst a large sample of women. The aim of this study was to determine the relationship between PA intensities on body size among a representative sample of women.
How they did it?
In this cross-sectional study, data were used from the UK Biobank Study, which is a large population-based study involving over half a million UK adults aged between 40-69 years. Physical activity was assessed using a previously validated survey, which asked participants to report the number of times in the past week they participated in walking, MPA and VPA for at least 10 minutes, and how much time they spent in these activities. To establish the effects of PA intensity on body composition, participants were categorised into three groups (1) 0% from VPA, (2) <33% from VPA, and (3) >33% from VPA. Body composition was assessed by measuring waist/hip circumference, Body Fat Percentage, whole body fat mass, trunk fat percentage, trunk fat mass and BMI.
What they found?
Data were available for 132,793 women aged 40-70 years (mean age=52.3 years). Just over one quarter of the sample was classified as obese according to BMI. When assessed across the three groups (0% VPA, <33% VPA & >33% VPA) there were significant differences observed across all assessments of body composition. A linear trend was observed suggesting that VPA was beneficial for body composition. For example, when compared to those within the 0% VPA, those with >33% VPA had the most favourable effects on BMI, Body Fat Percentage and waist circumference.
Ok, what does this mean to me?
Among a large sample of UK women, higher levels of VPA were associated with more favourable effects of body composition. Limitations of this study were that it was cross-sectional. It was not possible to look at an effect over time of the relationship between VPA and body composition. Nevertheless, these findings suggest that VPA is important for a healthy body composition. As long as clients have undertaken pre-exercise screening and have a base-level of fitness, trainers should encourage VPA into training programs.
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