title: Social support and leisure-time physical activity: longitudinal evidence from the Brazilian Pró-Saúde cohort study.
abstract: BACKGROUND
  Although social support has been observed to exert a beneficial influence on leisure-time physical activity (LTPA), multidimensional approaches examining social support and prospective evidence of its importance are scarce. The purpose of this study was to investigate how four dimensions of social support affect LTPA engagement, maintenance, type, and time spent by adults during a two-year follow-up.
  
  
  METHODS
  This paper reports on a longitudinal study of 3,253 non-faculty public employees at a university in Rio de Janeiro (the Pró-Saúde study). LTPA was evaluated using a dichotomous question with a two-week reference period, and further questions concerning LTPA type (individual or group) and time spent on the activity. Social support was measured by the Medical Outcomes Study Social Support Scale (MOS-SSS). To assess the association between social support and LTPA, two different statistical models were used: binary and multinomial logistic regression models for dichotomous and polytomous outcomes, respectively. Models were adjusted separately for those who began LTPA in the middle of the follow up (engagement group) and for those who had maintained LTPA since the beginning of the follow up (maintenance group).
  
  
  RESULTS
  After adjusting for confounders, statistically significant associations (p < 0.05) between dimensions of social support and group LTPA were found in the engagement group. Also, the emotional/information dimension was associated with time spent on LTPA (OR = 2.01; 95% CI 1.2-3.9). In the maintenance group, material support was associated with group LTPA (OR = 1.80; 95% CI; 1.1-3.1) and the positive social interaction dimension was associated with time spent on LTPA (OR = 1.65; 95% CI; 1.1-2.7).
  
  
  CONCLUSIONS
  All dimensions of social support influenced LTPA type or the time spent on the activity. However, our findings suggest that social support is more important in engagement than in maintenance. This finding is important, because it suggests that maintenance of LTPA must be associated with other factors beyond the individual's level of social support, such as a suitable environment and social/health policies directed towards the practice of LTPA.
authors.affiliation: Department of Epidemiology, Institute of Social Medicine, Rio de Janeiro State University, R Sao Francisco Xavier 524, 7th Floor, Rio de Janeiro, RJ 20550-900, Brazil. oliveira.jose.aldair@gmail.com
authors.forename: Aldair J
authors.initials: AJ
authors.lastname: Oliveira
authors.forename: Claudia S
authors.initials: CS
authors.lastname: Lopes
authors.forename: Antônio C Ponce
authors.initials: AC
authors.lastname: de Leon
authors.forename: Mikael
authors.initials: M
authors.lastname: Rostila
authors.forename: Rosane H
authors.initials: RH
authors.lastname: Griep
authors.forename: Guilherme L
authors.initials: GL
authors.lastname: Werneck
authors.forename: Eduardo
authors.initials: E
authors.lastname: Faerstein
mesh_terms: D000328:Adult; D001938:Brazil; D005260:Female; D005500:Follow-Up Studies; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007899:Leisure Activities; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D011446:Prospective Studies; D057566:Self Report; D012944:Social Support; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires