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.
James A. Betts
Rodrigo Reis, Ruth F. Hunter, Leandro Garcia, and Deborah Salvo
We are experiencing a planetary tipping point with global warming, environmental degradation, and losses in biodiversity. The burdens of these changes fall disproportionately on poor and marginalized populations. Physical activity promotion strategies need to be aligned with climate action commitments, incorporating the Intergovernmental Panel on Climate Change scenarios in physical activity action plans. The promotion strategies must consider equity a core value and promote physical activity to the most vulnerable populations so that they are protected from the ill-health impacts of a changing climate.
Seyyed Mohammadreza Mousavi and Takehiro Iwatsuki
Expectancies for success and autonomy support have been shown to facilitate motor learning and enhance motor performance. The purpose of the study was to examine whether we replicated (a) enhanced expectancies and autonomy support intervention enhanced motor skill learning in children, and (b) identified the underlying psychological mechanism. Sixty children kicked soccer balls with their dominant leg to a squared area target. Participants were randomly assigned to one of the four groups: enhanced expectancies and autonomy support (EE/AS), enhanced expectancies (EE), autonomy support (AS), or control (CON) groups. Participants learning the skill were or were not provided enhanced expectation instructions by making the task success easier and provided an opportunity to choose one of the three colored balls during their practice. Two days later, they performed retention and transfer tests. Results indicated that the EE/AS group had the highest scores, with main effects of autonomy support being significant and enhanced expectancies being marginally significant for the retention test and significant for the transfer test. The EE/AS group had the highest self-efficacy and perceived choice scores. Therefore, having high expectancies for success and being autonomous were important ingredients for facilitating motor skill learning in children.