The maximal amount of bone mass gained during growth (peak bone mass) is an important determinant of bone mass in later life and thereby an important determinant of fraeiure risk. Although genetic factors appear lo be primary determinants of peak bone mass, environmental factors such as physical activity and nutrition also contribute. In this article, bone growth and maintenance are reviewed, and mechanisms are described whereby physical activity can affect bone mass. Studies addressing the effects of physical activity on bone status in youth are reviewed: Although conclusive data are not yet available, considerable evidence supports the importance of activity, especially activity initiated before puberty. The critical role of energy in bone growth is outlined, and studies assessing the impact of calcium intake during childhood and adolescence are reviewed. Although results of intervention trials are equivocal, other evidence supports a role for calcium intake during growth. Recommendations for physical activity and nutrition, directed lochildren and adolescents, are presented.
Susan I. Barr and Heather A. McKay
Leigh Gabel, Heather M. Macdonald, Lindsay Nettlefold, and Heather A. McKay
Purpose: We examined the influence of vigorous physical activity (VPA) bout frequency on bone strength accrual across adolescence, independent of total volume of VPA. Methods: We measured VPA (6 metabolic equivalents; total volume and bout frequency <5 min in duration) annually using waist-worn accelerometers (ActiGraph GT1M) in 309 adolescents (9–20 y at baseline: 99, <13 y; 126, 13–18 y; 84, >18 y) over a maximum of 4 years. We applied finite element analysis to high-resolution peripheral quantitative computed tomography scans of the distal tibia (8% site) to estimate bone strength (failure load; F.Load, Newtons). We fit a mixed effects model with maturity offset (years from age at peak height velocity) as a random effect and sex, ethnicity, tibia length, lean body mass, and VPA (volume and bout frequency) as fixed effects. Results: VPA volume and bout frequency were positively associated with F.Load across adolescence; however, VPA volume did not predict F.Load once VPA bout frequency was included in the model. Participants in the upper quartile of VPA bout frequency (∼33 bouts per day) had 10% (500 N) greater F.Load across adolescence compared with participants in the lowest quartile (∼9 bouts per day; P = .012). Each additional daily bout of VPA was associated with 21 N greater F.Load, independent of total volume of VPA. Conclusion: Frequent VPA should be promoted for optimal bone strength accrual.
Catherine E. Tong, Joanie Sims Gould, and Heather A. McKay
Foreign-born older adults (FBOAs) are at risk for negative health transitions in Canada. Physical activity (PA) enhances health, yet we know very little about the PA habits of FBOAs in Canada. We conducted a mixed-method study in English, Cantonese, Mandarin, Punjabi, and Hindi, with 49 South Asian and Chinese FBOAs in Vancouver, Canada. In total, 49 participants completed surveys; of these 49, 46 wore accelerometers and 18 completed in-depth interviews. Participants’ mean daily step count was 7,876 (women: 8,172, men: 7,164, Chinese: 8,291, and South Asian: 7,196). The bulk of their time is spent in light and sedentary activities. PA is principally acquired through walking for errands and work performed in and around the home. This study challenges the assumption that FBOAs are less active than their nonimmigrant peers and confirms the key role of “nonexercise” and low activity, rather than moderate to vigorous, in older adults’ PA acquisition.
Heather A. McKay, Lindsay Nettlefold, Joanie Sims-Gould, Heather M. Macdonald, Karim M. Khan, and Adrian Bauman
Background: Choose to Move is one of few scaled-up health-promoting interventions for older adults. The authors evaluated whether Choose to Move participants maintained their intervention-related gains in physical activity (PA), mobility, and social connectedness 12 months after the intervention ended. Methods: The authors assessed PA, mobility, loneliness, social isolation, and muscle strength via questionnaire and objective measures in 235 older adults at 0 months (baseline), 6 months (end of intervention), and 18 months (12-months postintervention). The authors fitted linear mixed models to examine the change in each outcome from 6 to 18 months (primary objective) and 0 to 18 months (secondary objective) and reported by age group (60–74 and ≥75 y). Results: In younger participants, PA decreased between 6 and 18 months, but remained significantly higher than at baseline. Intervention-related benefits in loneliness, social isolation, mobility, and muscle strength were maintained between 6 and 18 months in the younger participants. Older participants maintained their intervention benefits in loneliness, mobility, and muscle strength. When compared with baseline values, PA levels in older participants were unchanged, whereas social isolation increased. Conclusions: Older adults maintained some, but not all, health benefits of Choose to Move 12 months after the intervention ended. Long-term commitments are needed to deliver effective health-promoting interventions for older adults if benefits are to be maintained.
Heather M. Macdonald, Lindsay Nettlefold, Adrian Bauman, Joanie Sims-Gould, and Heather A. McKay
Convergent validity and responsiveness to change of the single-item physical activity measure were assessed in adults aged 60 years and older, at baseline (n = 205) and 6 months (n = 177) of a health promotion program, Choose to Move. Spearman correlations were used to examine associations between physical activity as measured by the single-item measure and the Community Health Activities Model Program for Seniors (CHAMPS) questionnaire at baseline and for 6-month change in all participants and for sex and age (60–74 years, and ≥75 years) subgroups. Effect size assessed responsiveness to change in physical activity for both tools. Baseline physical activity by the single-item measure correlated moderately with physical activity by the CHAMPS questionnaire in all participants and subgroups. Correlations were weaker for change in physical activity. Effect size for physical activity change was larger for the single-item measure than for the CHAMPS questionnaire. The single-item measure is a valid, pragmatic tool for use in intervention and scale-up studies with older adults.
Anna M. Chudyk, Meghan Winters, Erin Gorman, Heather A. McKay, and Maureen C. Ashe
The authors investigated the use of Google Earth’s Street View option to audit the presence of built environment features that support older adults’ walking. Two raters conducted virtual (Street View) and in-the-field audits of 48 street segments surrounding urban and suburban assisted living sites in metropolitan Vancouver, BC, Canada. The authors determined agreement using absolute agreement. Their findings indicate that Street View may identify the presence of features that promote older adults’ walking, including sidewalks, benches, public washrooms, and destinations. However, Street View may not be as reliable as in-the-field audits to identify details associated with certain items, such as counts of trees or street lights; presence, features, and height of curb cuts; and sidewalk continuity, condition, and slope. Thus, the appropriateness of virtual audits to identify microscale built environment features associated with older adults’ walking largely depends on the purpose of the audits—specifically, whether the measurer seeks to capture highly detailed features of the built environment.
Dawn C. Mackey, Alexander D. Perkins, Kaitlin Hong Tai, Joanie Sims-Gould, and Heather A. McKay
We conducted Men on the Move, a 12-week randomized controlled feasibility trial of a scalable, choice-based, physical activity (PA) and active transportation intervention. Participants were community-dwelling men aged 60 years and older (n = 29 intervention [INT] and n = 29 waitlist control [CON]). Trained activity coaches delivered: (a) one-on-one participant consultations to develop personal action plans for PA and active transportation, (b) monthly group-based motivational meetings, (c) weekly telephone support, (d) complimentary recreation and transit passes, and (e) pedometers and diaries for self-monitoring. Men on the Move demonstrated high rates of recruitment, retention, and intervention adherence. INT chose a variety of group-based and individual PAs and destinations for their personal action plans. At 12 weeks, INT achieved more steps, moderate–vigorous PA, and energy expenditure than CON. INT was also more likely to take transit and meet national guideline levels of PA. At 24 weeks follow-up, INT benefits were sustained for moderate–vigorous PA and energy expenditure.
Katharine E. Reed, Darren E.R. Warburton, Crystal L. Whitney, and Heather A. McKay
Low physical fitness is associated with increased risk of cardiovascular disease (CVD) in adults and a higher incidence of CVD risk factors in children. Our aim was to compare the aerobic performance of Canadian children in 2004 with that of children measured 2 decades ago. We conducted a cross-sectional comparison of 2 data sets: (a) a 2004 cohort (n = 252) and (b) data from Leger’s 1981 cohort (n = 2,151). Performance was assessed using Leger’s 20 m Shuttle Run Test. First, we compared VO2max by cohort (in age and sex subgroups). Second, we used 1981 derived data, to re-create the original distribution curves, then calculated a 1981 equivalent percentile for each 2004 cohort child. We found that aerobic performance was lower at all ages in 2004 compared with 1981 (p < .01). Thus, the 50th percentile for fitness of children in 2004 was equivalent to that of children in the lowest 20% of fitness in 1981. We support the view that the performance of children on aerobic fitness tests is declining.
Lindsay Nettlefold, Samantha M. Gray, Joanie Sims-Gould, and Heather A. McKay
Lindsay Nettlefold, Samantha M. Gray, Joanie Sims-Gould, and Heather A. McKay
Interventions that are effective in research (efficacy or effectiveness) trials cannot improve health at a population level unless they are successfully delivered more broadly (scaled up) outside of the research setting. However, scale-up is often relegated to the too hard basket. Factors such as the need to adapt interventions prior to implementing them in diverse settings at scale, retaining fidelity to the intervention, and cultivating the necessary community and funding partnerships can all present a challenge. In the present review article, we present a scale-up case study—Choose to Move—an effective health-promoting intervention for older adults. The objectives of this review were to (a) describe the frameworks and processes adopted to implement, adapt, and scale up Choose to Move across British Columbia, Canada; (b) provide an overview of the phased approach to scale-up; and (c) share key lessons learned while implementing and scaling up health-promoting interventions with community partners across more than 2 decades.