Canadian Journal of Public Health

, Volume 110, Issue 2, pp 198–209 | Cite as

Influence of physical activity, screen time and sleep on inmates’ body weight during incarceration in Canadian federal penitentiaries: a retrospective cohort study

  • Claire JohnsonEmail author
  • Jean-Philippe Chaput
  • Maikol Diasparra
  • Catherine Richard
  • Lise Dubois
Quantitative Research



Recent research found that inmates experience undesirable and rapid weight gain during incarceration in Canadian federal penitentiaries. However, little is known about what factors and daily movement behaviours (e.g., physical activity, screen time, and sleep) influence weight gain during incarceration. This study examines how these 24-h movement/non-movement behaviours contribute to weight gain during incarceration.


This retrospective cohort study explored how weight change outcomes during incarceration (weight change, body mass index (BMI) change, and yearly weight gain) were influenced by physical activity, screen time, and sleep in a convenience sample of 754 inmates. The outcome measures were taken twice, once from participants’ medical chart at admission and again during a face-to-face follow-up interview (conducted in 2016–2017; mean follow-up time of 5.0 ± 8.3 years). Physical activity, screen time, and sleep were self-reported. The statistical analysis was chi-square testing, non-parametric median comparison testing, and regression analysis to control for confounders.


Inmates who engaged in at least 60 min of daily physical activities gained less weight (4.5 kg) compared to inmates who reported not exercising (8.3 kg). Different types of exercise (cardiovascular exercises, weight lifting, and team sports) were helpful at limiting weight gain, but playing sports was the most effective. Screen time and sleep were not associated with weight gain outcomes.


Among the behaviours examined, physical inactivity was significantly associated with higher weight gain during incarceration. However, even high levels of physical activity (> 60 min/day) were not sufficient to eliminate weight gain during incarceration in Canada.


Inmates Penitentiary BMI Obesity Physical activity Sedentary behaviours 



Des études récentes démontrent que les détenus gagnent du poids de façon excessive pendant leur incarcération en pénitenciers fédéraux au Canada. Cependant, il y a peu d’information sur les comportements (c’est-à-dire l’activité physique, le temps passé devant un écran, et le sommeil) qui contribuent à ce gain de poids. Cette étude examine comment ces comportements influencent le gain de poids des détenus durant leur incarcération.


Cette étude de cohorte rétrospective examine comment les indicateurs de changement de poids (changement de poids, changement d’indice de masse corporelle (IMC), et gain de poids annuel) ont varié en fonction de l’activité physique, du temps passé devant un écran et du sommeil, dans un échantillon de convenance de 754 détenus. Le poids et la taille ont été mesurés à deux reprises, soit à l’admission (tiré du dossier médical), puis lors de l’entrevue réalisée en 2016–2017 (durée d’incarcération moyenne de 5,0 ± 8,3 ans). Les comportements évalués ont été autodéclarés pendant l’entrevue. Les analyses statistiques réalisées incluent des tests du khi-carré et des analyses de régression.


Les détenus les plus actifs (>60 min par jour d’activité physique) ont gagné moins de poids (4,5 kg) que les détenus inactifs (8,3 kg). Les exercices cardiovasculaires, la musculation et le sport d’équipe ont réduit le gain de poids, mais les sports d’équipes ont été les plus efficaces. Le temps passé devant un écran et le sommeil n’ont pas influencé le changement de poids.


Parmi les facteurs évalués, l’activité physique est le principal facteur qui a limité le gain de poids durant l’incarcération. Toutefois, même à des niveaux d’activité physique élevés (>60 min par jour), les détenus canadiens ont gagné du poids pendant leur incarcération.


Détenus Pénitenciers IMC Obésité Activité physique Comportements sédentaires 



This study was funded by the Consortium national de formation en santé (CNFS). The funders had no involvement in study design; collection, analysis or interpretation of data; writing the manuscript; or the decision to submit the manuscript for publication.

Compliance with ethical standards

We obtained ethics approval through the Research Ethics Board at the University of Ottawa and the Research branch at Correctional Service Canada. Inmates volunteered to participate and provided their consent by signing our consent form. Since most inmates hesitated to sign documents or forms, because of low literacy and/or fear of reprisal, participants could provide verbal consent if they preferred (Gostin et al. 2007). The verbal consent was obtained by the research assistants and witnessed by correctional staff. All personal data collected were coded to ensure confidentiality.

Competing interests

Claire Johnson currently works as Coordinator of the Nutrition Management Program for Correctional Service Canada. The data and their interpretation are fully represented in the paper, and no censorship has occurred.

Supplementary material

41997_2018_165_MOESM1_ESM.docx (80 kb)
ESM 1 (DOCX 80 kb)


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Copyright information

© The Canadian Public Health Association 2019

Authors and Affiliations

  1. 1.Interdisciplinary School of Health SciencesUniversity of OttawaOttawaCanada
  2. 2.Healthy Active Living and Obesity Research GroupChildren’s Hospital of Eastern Ontario Research InstituteOttawaCanada
  3. 3.School of Epidemiology and Public HealthUniversity of OttawaOttawaCanada

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