The seated inactivity trial (S.I.T.): physical activity and dietary outcomes associated with eight weeks of imposed sedentary behavior

Date

2014-08-13

Journal Title

Journal ISSN

Volume Title

Publisher

Kansas State University

Abstract

Background: Time spent in sedentary behaviors, independent of physical activity levels, is a risk factor for chronic diseases and all-cause mortality. It is unknown whether physically active adults alter their dietary and/or physical activity behaviors in response to imposed sedentary time. The aim of this study was to determine whether imposing 10 hours of sedentary time per week for 8 weeks would alter physical activity and/or dietary profiles of physically active adults.

Methods: Sixteen physically active, healthy young adults were randomized into either the no-intervention control (CON) group (n=8) or the sedentary-intervention (SIT) group (n=8). SIT participants attended monitored sedentary sessions for 10 hours per week (4 days; 2.5 hours) for 8 weeks. Assessments occurred at baseline, and weeks 4 and 8. Dietary information was collected through 3-day food records and physical activity was assessed through 7 days of accelerometry (Actical at the wrist).

Results: There were no differences in physical activity profiles in SIT or CON groups when baseline and week-8 average (average weeks) were compared to the week-4 assessment. Differences in step counts comparing the average weeks and week 4 were not significantly different between CON and SIT groups (CON = 615.1 ± 3019.1, SIT= -1158.0 ± 3373.0 steps, p=0.287). There were no differences in sedentary (p=0.366), light (p=0.293), moderate (p=0.656) or vigorous (p=0.701) physical activity when average weeks were compared to one of imposed sedentary behavior. A greater number of SIT (4/8) participants had lower step counts during the imposed sedentary week, when compared to CON (1/8) participants. There was no difference (p>0.05) between CON and SIT groups for total calories consumed at any time-point. Caloric intake decreased significantly in the SIT group compared to the CON group (SIT = -27.9 ± 22.8%, CON = 10.0 ± 37.6%, p=0.028). More SIT (7/8) than CON (3/8) participants decreased caloric intake from baseline to 8 weeks (p>0.05).

Conclusion: Physically active young adults did not alter physical activity profiles, but did decrease their caloric intake, in response to 8 weeks of imposed sedentary time. These findings may indicate a compensatory mechanism to imposed sitting in physically active adults.

Description

Keywords

Nutrition, Physical activity, Imposed sedentary behavior, Riley County Research and Extension, Public health, Walk Kansas

Graduation Month

August

Degree

Master of Public Health

Department

Department of Human Nutrition

Major Professor

Mark Haub

Date

2014

Type

Thesis

Citation