Research Publications (Health Sciences)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/216
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Item Steps that count : pedometer-measured physical activity, self-reported physical activity and current guidelines- how do they relate?(South African Sports Medicine Association, 2014) Pillay, Julian David; Kolbe-Alexander, Tracy L.; Proper, Karin I.; Tomaz, Simone A.; Van Mechelen, Willem; Lambert, Estelle V.Background. The association between self-perceived and actual physical activity, with particular reference to physical activity guidelines, may be an important factor in determining the extent of uptake of and compliance with physical activity. Objectives. To examine the association between self-perceived and actual physical activity in relation to physical activity guidelines, with reference to volume, intensity and duration of steps/day, and to establish the level of agreement between pedometer-measured and selfreported ambulatory physical activity, in relation to current guidelines. Methods. A convenience sample of adults (N=312; mean (standard deviation) age 37 (9) years), wore a pedometer (minimum 3 consecutive days) and completed a questionnaire that included information on physical activity patterns. Analyses of covariance, adjusted for age and gender, compared volume- and intensity-based steps according to meeting/not meeting guidelines (self-reported). The extent of agreement between self-reported and pedometer-measured physical activity was also determined. Results. Average (SD) steps/day were 6 574 (3 541). Of a total of 312 participants’ self-reported data, those meeting guidelines (n=63) accumulated significantly more steps/day than those not meeting guidelines (8 753 (4 251) v. 6 022 (3 114) total steps/day and 1 772 (2 020) v. 421 (1 140) aerobic steps/day, respectively; p<0.0001). More than half of the group who self-reported meeting the guidelines did not meet guidelines as per pedometer data. Conclusion. The use of pedometers as an alternative and/or adjunct to self-reported measures is an area for consideration. Steps/day recommendations that consider intensity-based steps may provide significant effects in improving fitness and health.Item Steps that count! : a feasibility study of a pedometer-based, health-promotion intervention in an employed, South African population(South African Sports Medicine Association, 2014) Pillay, Julian David; Kolbe-Alexander, Tracy L.; Proper, Karin I.; Van Mechelen, Willem; Lambert, Estelle V.Background. The emergence of the pedometer as a useful motivational aid for increasing physical activity (PA) has supported its use in PA interventions. Objectives. To examine the feasibility of a 10-week pedometer-based intervention complemented by regular motivational messages, to increase ambulatory PA; and to determine the minimum sample size required for a randomised, controlled trial (RCT). Methods. Participants, sourced by convenience sampling of employees from an academic institution, were randomly assigned to either an intervention group (IG) (n=11) or control group (CG) (n=11), following baseline health measurements and blinded pedometer wear (week 1). Participants in the IG subsequently wore an unblinded pedometer (10 weeks) to self-monitor daily steps. Individualised messages using pedometer data (IG) and general motivational messages (IG and CG) were provided bi-weekly. Blinded pedometer wear (IG and CG) and a feedback questionnaire (IG) were completed at week 12. Pedometer data were compared between the IG and CG at week 12. Results. Participants’ perceptions of the intervention supported the benefit of the pedometer as a useful motivational aid and a reminder to increase steps per day. Occupational sitting time and inability to incorporate PA into daily routine emerged as the main barrier to adherence. Steps per day increased more in the IG (mean ± standard deviation (SD) 996±1 748) than in the CG (mean±SD 97±750). Modest improvements were noted in all clinical measures (IG). Conclusion. Based on the improvement of 1 000 steps/day (IG), a minimum of 85 participants in the IG and CG, respectively, is required for a future RCT (80% power; p<0.05). We recommend a minimum of 150 participants in each group to account for loss to follow-up and to allow for subgroup analyses.Item The association between daily steps and health, and the mediating role of body composition : a pedometer-based, cross-sectional study in an employed South African population(Biomed Central, 2015) Pillay, Julian David; Van der Ploeg, Hidde P.; Kolbe-Alexander, Tracy L.; Proper, Karin I.; Van Stralen, Maartje; Tomaz, Simone A.; van Mechelen, Willem; Lambert, Estelle V.Background: Walking is recognized as an easily accessible mode of physical activity and is therefore supported as a strategy to promote health and well-being. To complement walking, pedometers have been identified as a useful tool for monitoring ambulatory physical activity, typically measuring total steps/day. There is, however, little information concerning dose-response for health outcomes in relation to intensity or duration of sustained steps. We aimed to examine this relationship, along with factors that mediate it, among employed adults. Methods: A convenience sample, recruited from work-site health risk screening (N = 312, 37 ± 9 yrs), wore a pedometer for at least three consecutive days. Steps were classified as “aerobic” (≥100 steps/minute and ≥10 consecutive minutes) or “non-aerobic” (<100 steps/minute and/or <10 consecutive minutes). The data were sub-grouped according to intensity-based categories i.e. “no aerobic activity”, “low aerobic activity” (1-20 minutes/day of aerobic activity) and “high aerobic activity” (≥21 minutes/day of aerobic activity), with the latter used as a proxy for current PA guidelines (150-minutes of moderate-intensity PA per week). Health outcomes included blood pressure, body mass index, percentage body fat, waist circumference, blood cholesterol and blood glucose. Analysis of covariance, adjusting for age, gender and total steps/day were used to compare groups according to volume and intensity-based steps categories. A further analysis compared the mediation effect of body fat estimates (percentage body fat, body mass index and waist circumference) on the association between steps and health outcomes, independently. Results: Average steps/day were 6,574 ± 3,541; total steps/day were inversely associated with most health outcomes in the expected direction (p < 0.05). The “no aerobic activity” group was significantly different from the “low aerobic activity” and “high aerobic activity” in percentage body fat and diastolic blood pressure only (P < 0.05). Percentage body fat emerged as the strongest mediator of the relationship between steps and outcomes, while body mass index showed the least mediation effect. Conclusion: The study provides a presentation of cross-sectional pedometer data that relate to a combination of intensity and volume-based steps/day and its relationship to current guidelines. The integration of volume, intensity and duration of ambulatory physical activity in pedometer-based messages is of emerging relevance.