September 22, 2016

Daniel P. Bailey1, David R. Broom2, Bryna C.R. Chrismas3, Lee Taylor4, Edward Flynn1, and John Hough1

1 Institute for Sport and Physical Activity Research, Department of Sport Science and Physical Activity, University of Bedfordshire, Polhill Avenue, Bedford, MK41 9EA, UK.

2 Academy of Sport and Physical Activity, Sheffield Hallam University, Sheffield, S10 2BP, UK.

3 Sport Science Program, College of Arts and Sciences, Qatar University, Doha, Qatar.
4 ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar

Engaging in prolonged uninterrupted bouts of sitting has recently been identified as a risk factor for cardiometabolic diseases including heart disease and Type 2 diabetes. This is regardless of the time spent in structured exercise. Sitting reduces daily energy expenditure but this is not accompanied by compensatory reductions in appetite or energy intake and may therefore contribute to weight gain. Structured exercise bouts can suppress appetite and create energy deficits by expending energy that is not compensated for by increased food take in subsequent meals. Breaking up prolonged sitting with short frequent activity bouts can reduce cardiometabolic disease risk markers over a single day and this form of movement is now recommended for health promotion. The objective of this study was to examine appetite and energy intake responses to breaking up prolonged sitting with regular short bouts of light- and moderate-intensity walking in sedentary individuals.

Thirteen (7 females) sedentary and inactive participants (sitting >7 hours/day and engaging in <150 minutes/week of moderate-to-vigorous physical activity) with a mean age of 27±9 years and body fat of 24±8% took part in three 5 hour trials in random order: 1) uninterrupted sitting, 2) seated with 2 minute bouts of light-intensity walking (3.2 km/hour) every 20 minutes, and (3) seated with 2 minute bouts of moderate-intensity walking (6-8 km/hour) every 20 minutes. A standardised liquid test meal containing 75 g carbohydrate and 50 g fat was consumed at the start of the 5 hour trial and an ad libitum pasta test meal (74% carbohydrate, 21% protein, and 5% fat) was provided at the end of the trial with participants being instructed to “eat as much as they like until satisfied”. During each trial, hourly blood samples were taken to measure circulating concentrations of the appetite-regulating hormones acylated ghrelin (appetite stimulant) and peptide YY (appetite suppressant), in addition to blood sugar levels. Every 30 minutes the participants also completed a questionnaire asking them to rate their perceived appetite levels e.g. “How hungry do you feel”.

The results indicated that blood sugar levels were 48-57% lower in the moderate-intensity activity breaks conditions compared with uninterrupted sitting and light-intensity activity breaks. Perceived appetite and appetite-regulating hormone responses to the standardised test meal were not altered when breaking up prolonged sitting with frequent short bouts of light- or moderate-intensity walking. There was also no difference in absolute ad libitum meal energy intake between the uninterrupted sitting and activity breaks conditions. This meant that relative energy intake (calculated as energy intake during the trials minus the net energy expenditure of the activity bouts) was 39% lower in the light-intensity activity breaks condition and 120% lower in the moderate-intensity activity breaks condition compared with uninterrupted sitting. This suggests that the energy expended through activity used to break up prolonged sitting is not compensated for by increased food intake in a subsequent meal. This leads to a short-term energy deficit that if continued over time may be beneficial for body weight control.

This article is a summary of an article published in Applied Physiology, Nutrition & Metabolism. If you intend to cite any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Translation Committee.

Original Article

Bailey DP, Broom DR, Chrismas BCR, Taylor L, Flynn E, Hough J (2016). Breaking up prolonged sitting time with walking does not affect appetite or gut hormone concentrations but does induce an energy deficit and suppresses postprandial glycaemia in sedentary adults. Applied Physiology, Nutrition and Metabolism, 41(3): 324-331. DOI: 10.1139/apnm-2015-0462.