Alannah K.A. McKay, Peter Peeling, David B. Pyne, Nicolin Tee, Marijke Welveart, Ida A. Heikura, Avish P. Sharma, Jamie Whitfield, Megan L. Ross, Rachel P.L. van Swelm, Coby M. Laarakkers, and Louise M. Burke
This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10 g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6 g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3 hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17–23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26 km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3 hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p = .004) and hotter trial ambient temperatures (p = .014) were associated with greater hepcidin levels 3 hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3 hr postexercise.
Jessica Murphy, Karen A. Patte, Philip Sullivan, and Scott T. Leatherdale
The mental health benefits of physical activity may relate more to the context of the behavior, rather than the behavior of being active itself. The association between varsity sport (VS) participation, depression, and anxiety symptoms was explored using data from 70,449 high school students from the Cannabis use, Obesity, Mental health, Physical activity, Alcohol use, Smoking, and Sedentary behavior study. The model adjusted for potential covariates; interactions by sex and participation in outside of school sport (OSS) were explored. Overall, 70% and 24% of respondents met or exceeded cutoff values for depression and anxiety, respectively. Students participating in VS had lower symptoms of anxiety and depression compared with nonparticipants. Results were consistent regardless of OSS participation; associations were strongest among students who participated in both VS and OSS and males. Participation in VS may prove beneficial for the prevention and/or management of depression or anxiety symptoms, particularly among males. An additive beneficial effect of OSS on depression and anxiety scores may exist.
Noah Wexler, Yingling Fan, Kirti V. Das, and Simone French
Background: Neighborhood parks are important locations to encourage and stimulate physical activity (PA) among the urban population. This study aims to evaluate the impact of an informational intervention on adult park use and PA behaviors in 3 low-income, racially diverse urban neighborhoods in Minneapolis, MN. Method: The study employed a household-level randomized controlled trial and collected baseline and follow-up data from 171 participants. Within each neighborhood, participants were randomized to an informational intervention or to a no-intervention comparison. Intervention households received monthly, neighborhood-specific newsletters about park-based PA opportunities, park program brochures, trail maps, and activity guides. Results: The average treatment effect of the newsletter intervention was positive yet moderated by respondent age. For a 20-year-old resident, treatment was associated with 0.97 (P < .05) additional park visits and 31.24 (P < .05) additional minutes of park-based PA over a 3-day recall period. For 40-year-old respondents, these positive effects are smaller at 0.36 (P < .05) additional visits and 4.66 (P < .05) additional minutes, respectively. Conclusions: An intervention to increase awareness about park-based PA opportunities and benefits increased self-reported park visits and in-park PA among adults who lived in low-income, racially diverse neighborhoods.
Naroa Etxebarria, Nicole A. Beard, Maree Gleeson, Alice Wallett, Warren A. McDonald, Kate L. Pumpa, and David B. Pyne
Gastrointestinal disturbances are one of the most common issues for endurance athletes during training and competition in the heat. The relationship between typical dietary intake or nutritional interventions and perturbations in or maintenance of gut integrity is unclear. Twelve well-trained male endurance athletes (peak oxygen consumption = 61.4 ± 7.0 ml·kg−1·min−1) completed two trials in a randomized order in 35 °C (heat) and 21 °C (thermoneutral) conditions and kept a detailed nutritional diary for eight consecutive days between the two trials. The treadmill running trials consisted of 15 min at 60% peak oxygen consumption, 15 min at 75% peak oxygen consumption, followed by 8 × 1-min high-intensity efforts. Venous blood samples were taken at the baseline, at the end of each of the three exercise stages, and 1 hr postexercise to measure gut integrity and the permeability biomarker concentration for intestinal fatty-acid-binding protein, lipopolysaccharide, and lipopolysaccharide-binding protein. The runners self-reported gut symptoms 1 hr postexercise and 3 days postexercise. The heat condition induced large (45–370%) increases in intestinal fatty-acid-binding protein, lipopolysaccharide-binding protein, and lipopolysaccharide concentrations compared with the baseline, but induced mild gastrointestinal symptoms. Carbohydrate and polyunsaturated fat intake 24 hr preexercise were associated with less lipopolysaccharide translocation. Protein, carbohydrate, total fat, and polyunsaturated fat intake (8 days) were positively associated with the percentage increase of intestinal fatty-acid-binding protein in both conditions (range of correlations, 95% confidence interval = .62–.93 [.02, .98]). Typical nutrition intake partly explained increases in biomarkers and the attenuation of symptoms induced by moderate- and high-intensity exercise under both heat and thermoneutral conditions.
Nicole C.A. Strock, Kristen J. Koltun, and Emily A. Ricker
Megan A. Kuikman, Margo Mountjoy, Trent Stellingwerff, and Jamie F. Burr
Karen Milton, Nick Cavill, Anna Chalkley, Charlie Foster, Sjaan Gomersall, Maria Hagstromer, Paul Kelly, Tracy Kolbe-Alexander, Jacqueline Mair, Matthew McLaughlin, James Nobles, Lindsey Reece, Trevor Shilton, Ben J. Smith, and Jasper Schipperijn
Background: The International Society for Physical Activity and Health (ISPAH) is a leading global organization working to advance research, policy, and practice to promote physical activity. Given the expanding evidence base on interventions to promote physical activity, it was timely to review and update a major ISPAH advocacy document—Investments that Work for Physical Activity (2011). Methods: Eight investment areas were agreed upon through consensus. Literature reviews were conducted to identify key evidence relevant to policymakers in each sector or setting. Results: The 8 investment areas were as follows: whole-of-school programs; active transport; active urban design; health care; public education; sport and recreation; workplaces; and community-wide programs. Evidence suggests that the largest population health benefit will be achieved by combining these investments and implementing a systems-based approach. Conclusions: Establishing consensus on ‘what works’ to change physical activity behavior is a cornerstone of successful advocacy, as is having appropriate resources to communicate key messages to a wide range of stakeholders. ISPAH has created a range of resources related to the new investments described in this paper. These resources are available in the ‘advocacy toolkit’ on the ISPAH website (www.ispah.org/resources).