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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.

Open access
Open access

Vilton E.L. de Moura e Silva, Jason M. Cholewa, François Billaut, Ralf Jäger, Marcelo C. de Freitas, Fabio S. Lira and Fabrício E. Rossi

Context: Capsaicinoids and capsinoids (CAP) are natural substances found primarily in chili peppers and other spicy foods that agonize the transient receptor potential vanilloid-1 in the mouth, stomach, and small intestine. Several studies have shown CAP to be a potential antiobesity agent and to exhibit an analgesic effect in both rodents and humans. However, there is no scientific consensus about the effects of CAP on physical exercise performance and its physiological mechanisms of action. Purpose: This systematic review aimed to better elucidate the effects of CAP compounds as ergogenic aids and to discuss underlying mechanisms of action by which this supplement may potentially enhance endurance performance and muscular strength. Conclusions: Among 22 studies included in the review, 14 examined the effects of capsaicinoid or capsinoid compounds on endurance and resistance exercise performance in animals, with 9 studies showing benefits on performance. In humans, 8 studies were included: 3 demonstrated significant acute endurance benefits and 2 showed acute resistance exercise performance benefits compared with a placebo condition. Therefore, while more mechanistic studies are necessary to confirm these outcomes in humans, the available scientific literature appears to suggest that these compounds could be considered an effective nutritional strategy to improve exercise performance.

Open access

Jos J de Koning, Teun van Erp, Rob Lamberts, Stephen Cheung and Dionne Noordhof

Open access

Daniel Boullosa, Marco Beato, Antonio Dello Iacono, Francisco Cuenca-Fernández, Kenji Doma, Moritz Schumann, Alessandro Moura Zagatto, Irineu Loturco and David G. Behm

Open access

Ian C. Smith and Brian R. MacIntosh

Open access

Dean Barker, Mikael Quennerstedt, Anna Johansson and Peter Korp

Aim: To provide insight into how physical education teachers use discursive resources related to obesity to create particular professional identities. Method: Data come from focus group and individual interviews with physical education teachers in Sweden. Discourse theory on teacher identities frame the analysis of the empirical material. Results: Data suggest that teachers in Sweden make use of six distinct but related discursive contributions to produce three professional identities: the caring practitioner, an identity concerned with ensuring all pupils irrespective of size participate in physical education; the activity luminary, an identity that focuses on inspiring pupils toward activity across the lifespan, and; the body rationalist, an identity concerned with challenging unrealistic media discourses and reassuring pupils that they have “normal” bodies. Discussion: The identities appear more inclusive, sensitive, and critical than current physical education literature on obesity suggests, however they also contain elements that are fundamentally unsympathetic to overweight individuals.