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Edgar J. Gallardo and Andrew R. Coggan

Consumption of beetroot juice (BRJ) supplements has become popular among athletes because beets tend to be rich in nitrate (NO3), which can enhance exercise performance by increasing nitric oxide production. The NO3 content of beets can vary significantly, however, making it difficult to know how much NO3 any product actually contains. Samples from 45 different lots of 24 different BRJ products from 21 different companies were therefore analyzed for NO3 (and nitrite [NO2]) concentration using high-performance liquid chromatography. The NO3 and NO2 content (i.e., amount per serving) was then calculated based on either (a) the manufacturer’s recommended serving size (for prepackaged/single dose products) or (b) as used in previous studies, a volume of 500 ml (for BRJ sold in bulk containers). There was moderate-to-large variability in NO3 content between samples of the same product, with a mean coefficient of variation of 30% ± 26% (range 2–83%). There was even greater variability between products, with a ∼50-fold range in NO3 content between the lowest and highest. Only five products consistently provided ≥5 mmol of NO3/serving, which seems to be the minimal dose required to enhance exercise performance in most individuals. NO2 contents were generally low (i.e., ≤0.5% compared with NO3), although two products contained 10% and 14%. The results of this study may be useful to athletes and their support staff contemplating which (if any) BRJ product to utilize. These data may also offer insight into variability in the literature with respect to the effects of BRJ on exercise performance.

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Tiago V. Barreira, Stephanie T. Broyles, Catrine Tudor-Locke, Jean-Philippe Chaput, Mikael Fogelholm, Gang Hu, Rebecca Kuriyan, Estelle V. Lambert, Carol A. Maher, José A. Maia, Timothy Olds, Vincent Onywera, Olga L. Sarmiento, Martyn Standage, Mark S. Tremblay, Peter T. Katzmarzyk and for the ISCOLE Research Group

Background: To determine if children’s moderate to vigorous physical activity (MVPA) and sedentary time varied across levels of household income in countries at different levels of Human Development Index (HDI), consistent with the theory of epidemiological transition. Methods: Data from 6548 children (55% girls) aged 9–11 years from 12 countries at different HDI levels are used in this analysis to assess MVPA and sedentary time (measured using ActiGraph accelerometers) across levels of household income. Least-square means are estimated separately for boys and girls at the estimated 10th, 50th, and 90th percentiles of HDI for the sample. Results: For boys, time in MVPA is negatively associated with income at the 10th and 50th percentiles of HDI (both P < .002). For girls, time in MVPA is negatively associated with income at the 10th and 50th percentiles of HDI (all P < .01) and positively related with income at the 90th percentile (P = .04). Sedentary time is positively associated with income at the 10th percentile of HDI for boys (P = .03), but not for girls. Conclusions: Results support the possibility of an epidemiological transition in physical activity, with lower levels of MVPA observed at opposite levels of income depending on the HDI percentile. This phenomenon was not observed for sedentary time.

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Kazuhiro Harada, Kouhei Masumoto and Narihiko Kondo

Background: Although the beneficial effects of physical activity and exercise on mental health are well known, the optimal conditions for them for benefitting mental health are still unclear. Engaging in exercise with others might have more desirable effects on mental health than engaging in exercise alone. This study examined the associations between exercising alone, exercising with others, and mental health among middle-aged and older adults. Methods: Baseline and 1-year follow-up surveys were conducted with 129 individuals. Time spent exercising alone or with others was measured using a 7-day diary survey. Total physical activity was objectively measured using an accelerometer. Mental well-being was assessed using the simplified Japanese version of the World Health Organization Five Well-Being Index, and mental distress was assessed using the Japanese version of the Kessler Distress Scale (K6). Results: Cross-lagged and simultaneous effects models revealed that exercising with others positively influenced mental well-being. Exercising alone and total physical activity did not significantly influence mental well-being. Neither total physical activity, exercising alone, nor exercising with others was significantly associated with mental distress. Conclusion: Engaging in exercise with others could be effective in improving mental well-being relative to engaging in exercise alone.

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Jennifer Ann McGetrick, Krystyna Kongats, Kim D. Raine, Corinne Voyer and Candace I.J. Nykiforuk

Background: Attitudes and beliefs of policy influencers and the general public toward physical activity policy may support or impede population-level action, requiring improved understanding of aggregate preferences toward policies that promote physical activity. Methods: In 2016, the Chronic Disease Prevention Survey was administered to a census sample of policy influencers (n = 302) and a stratified random sample of the public (n = 2400) in Alberta and Québec. Using net favorable percentages and the Nuffield Council on Bioethics’ intervention ladder framework to guide analysis, the authors examined support for evidence-based healthy public policies to increase physical activity levels. Results: Less intrusive policy options (ie, policies that are not always the most impactful) tended to have higher levels of support than policies that eliminated choice. However, there was support for certain types of policies affecting influential determinants of physical activity such as the built environment (ie, provided they enabled rather than restricted choice) and school settings (ie, focusing on children and youth). Overall, the general public indicated stronger levels of support for more physical activity policy options than policy influencers. Conclusions: The authors’ findings may be useful for health advocates in identifying support for evidence-based healthy public policies affecting more influential determinants of physical activity.

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Shona L. Halson, Alan G. Hahn and Aaron J. Coutts

Open access

Brigid M. Lynch, Charles E. Matthews, Katrien Wijndaele and on behalf of the Sedentary Behaviour Council of the International Society for Physical Activity and Health

Open access

Viviene A. Temple, Dawn L. Lefebvre, Stephanie C. Field, Jeff R. Crane, Beverly Smith and Patti-Jean Naylor

This study examined the influence of physical health and well-being vulnerability on participation in physical activities, and whether motor skill proficiency mediated this relationship. Kindergarten children (n = 260) completed the Test of Gross Motor Development-2 and the Children’s Assessment of Participation and Enjoyment survey. A multivariate analysis of covariance was used to compare the motor skills and participation in physical activities of children in schools classified as more or less vulnerable. We also examined whether motor skill proficiency mediated the relationship between vulnerability status and participation. Children in neighborhoods with higher vulnerability demonstrated lower motor skill proficiency and participation. Object control skill proficiency mediated the relationship between vulnerability and participation. Children from more vulnerable schools started their school career with less developed motor skills and a narrower array of recreation participation. Children in vulnerable neighborhoods need more opportunities to master object controls skills and access recreational activities. Fortunately, motor skill proficiency among children considered ‘at risk’ is amenable to improvement and intervention early in the children’s school career may have a beneficial impact on children’s physical activity at school and beyond the school environment.

Open access

Trent Stellingwerff, Ingvill Måkestad Bovim and Jamie Whitfield

Middle-distance runners utilize the full continuum of energy systems throughout training, and given the infinite competition tactical scenarios, this event group is highly complex from a performance intervention point of view. However, this complexity results in numerous potential periodized nutrition interventions to optimize middle-distance training adaptation and competition performance. Middle-distance race intensity is extreme, with 800- to 5,000-m races being at ∼95% to 130% of VO2max. Accordingly, elite middle-distance runners have primarily Type IIa/IIx fiber morphology and rely almost exclusively on carbohydrate (primarily muscle glycogen) metabolic pathways for producing adenosine triphosphate. Consequently, the principle nutritional interventions that should be emphasized are those that optimize muscle glycogen contents to support high glycolytic flux (resulting in very high lactate values, of >20 mmol/L in some athletes) with appropriate buffering capabilities, while optimizing power to weight ratios, all in a macro- and microperiodized manner. From youth to elite level, middle-distance athletes have arduous racing schedules (10–25 races/year), coupled with excessive global travel, which can take a physical and emotional toll. Accordingly, proactive and integrated nutrition planning can have a profound recovery effect over a long race season, as well as optimizing recovery during rounds of championship racing. Finally, with evidence-based implementation and an appropriate risk/reward assessment, several ergogenic aids may have an adaptive and/or performance-enhancing effect in the middle-distance athlete. Given that elite middle-distance athletes undertake ∼400 to 800 training sessions with 10–25 races/year, there are countless opportunities to implement various periodized acute and chronic nutrition-based interventions to optimize performance.