Background: Levels of physical activity are significantly lower among individuals with end-stage renal disease (ESRD) compared to their healthy sedentary counterparts. Low levels of self-efficacy (SE) with respect to exercise may contribute to a sedentary lifestyle in the ESRD population. Therefore, in a pilot investigation we examined the effects of an 8-week intra-dialytic (ID) exercise program on SE and physical activity (PA) in hemodialysis (HD) patients and determined the appropriateness and sensitivity of the selected outcome measures and proposed intervention. Methods: HD patients were randomized into an Exercise group (EX, n=4) or a Control group (CON, n=4). The EX group cycled for approximately 60 min during HD, thrice weekly for 8 weeks. The CON group continued with their usual activity. At 8 weeks, participants in both groups had the option to participate in the exercise program. Physical Activity was determined using the Human Activity Profile (Maximal Activity Score, MAS; Adjusted Activity Score, AAS) and SE was evaluated using the Chronic Disease Self-Efficacy Scale (CDSES) and Exercise Self-Efficacy Scale (ESES). Measures were obtained at pre, post and 8 weeks following the intervention. Results: No significant changes in PA or SE occurred between or within groups at any time point. Limited statistical power due to the small sample size and a ceiling effect due to initial high-function levels of the participants may have contributed to the lack of significant changes. MAS and AAS were generally lower in the CON group. Age was significantly associated with the AAS, MAS, and the Perform Social/Recreational Activities sub-scale of the CDSES. Serum albumin was significantly related to the AAS and the Exercise Regularly and Do Chores sub-scales of the CDSES. Conclusions: Age and albumin should be taken into account when assessing physical activity in HD patients. Recruitment of additional participants is required to more clearly define the role of intra-dialytic exercise in enhancing exercise self-efficacy and physical activity in HD patients. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2010-07-27 09:51:11.297

Background: Shift work is associated with increased risk of cardiovascular disease and cancer, where decreased melatonin has been proposed as an intermediate in the causal pathway. The influence of physical activity on melatonin has rarely been studied in an observational setting, and it may be important in mediating the effects of shift work. We aimed to assess the influence of energy expended during physical activity of different intensities on melatonin among rotating shift nurses. We hypothesized that physical activity before the night shift would lessen the decrease in melatonin production that occurs with exposure to light at night. Methods: 123 female rotating shift nurses working at Kingston General Hospital were recruited over a one-year period. Physical activity and sedentary behaviours for each participant were recorded during both a day and a night shift using activity diaries, and analysis was restricted to activities between 3 p.m. and 7 a.m. Concentrations of urinary 6-sulfatoxymelatonin, a melatonin metabolite, in morning void urine samples were analyzed for each shift. Results: The average age of participants was 41 years, and 60% were overweight or obese (body mass index ≥ 25 kg/m2). An average of 6.9 and 5.2 hours of sleep were reported after the day shift and night shift, respectively. Sedentary behaviours such as standing and television watching accounted for over half of the total reported energy expenditure. During the day shift, energy expended in moderate and vigorous intensity physical activity between 3 p.m. and 7 a.m. was negatively associated with melatonin levels (p=0.024, R2 = 0.09). During the night shift, energy expended in sedentary behaviours was negatively associated with melatonin levels (p=0.008, R2 = 0.03). Conclusions: Physical activity energy expenditure explains only a small amount of melatonin variation, suggesting that other factors are influencing melatonin production, or that melatonin production is minimally effected by these patterns of physical activity. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2010-09-01 11:22:35.915

Background: Canadian children's physical inactivity levels are a public health concern due to their association with chronic diseases and mental health. Families are considered gatekeepers to children’s behaviours, and may influence their physical activity (PA). Purpose: To investigate the influence of family PA factors (i.e. parental PA, parents’ perspectives on family support for PA and family PA rules) on children’s PA levels and their free-play PA facility use. Methods: Kingston Gets Active distributes the Grade 5 Community PA Pass to approximately 2,500 grade 5 students in Kingston and surrounding areas yearly. The pass grants students free access to local pools (n=4), YMCA (n=1), and arenas (n=8) for recreational PA for 10 months. In fall 2006, 292 grade 5 students (54% girls; mean age=9.99, SD=0.35) from 24 elementary schools completed a baseline (BL) questionnaire that assessed demographics, children’s PA levels, PA facility use, and family support for PA. In spring 2007, 272 students completed a follow-up (FU) questionnaire with additional items assessing pass use. In spring 2007, 189 parents (83% mothers) participated in a telephone interview assessing family PA variables and community resources influencing pass and PA facility use. Results: The majority of students (69%) reported using their pass at least once; and although children’s PA did increase (t(230) = -4.91, p < .05), free-play PA facility use did not increase from BL to FU. Multiple hierarchical regression analysis indicated that individual-level variables were better predictors of children’s PA (ΔR2 = .28, F(2, 136) = 26.99, p < .001) and their free-play PA facility use (ΔR2 = .36, F(4, 151) = 21.55, p < .001) as compared to family-level PA variables (children’s PA: ΔR2 = .001, F(3, 133) = 0.089, p =.97; free-play PA facility use: ΔR2 = .007, F(3, 148) = 0.54, p =.65). Parents indicated that other social, organizational, and community factors influenced children’s free-play PA facility use. Conclusions: Children’s PA and free-play PA facility use are influenced by a multitude of interrelated factors within the socio-ecological model. More research should explore associations between family factors and children’s free-play PA facility use. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2010-09-24 02:48:17.239

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