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.
Lambros Stefanou, Niki Tsangaridou, Charalambos Y. Charalambous, and Leonidas Kyriakides
Purpose: Teacher content knowledge (CK) and its contribution to student achievement (SA) are understudied in physical education, especially concerning the examination of the effectiveness of professional development (PD) programs using direct measures of teachers’ CK and SA. To make progress in this research area, this study investigated the contribution of a content-focused PD program to teachers’ CK and SA in basketball, using direct measures thereof. Methods: A quasi-experimental design was utilized to examine the contribution of a PD program. The authors measured the CK of 52 elementary classroom teachers and their fifth or sixth grade students’ (n = 913) achievement in basketball before and after the PD program. The data were analyzed using unilevel and multilevel regression analyses. Results: Teachers who participated in the PD program exhibited higher learning gains in their CK; their students also exhibited higher learning gains. Discussion and Conclusion: The study findings suggest that PD programs focused on enhancing teachers’ CK might also support SA.
Insook Kim and Phillip Ward
Purpose: This study examined the effects of a specialized content knowledge workshop on developing teachers’ content development and adaptive competence in teaching badminton. Method: A quasi-experimental design was employed with three middle school physical education teachers who taught five or six badminton lessons before and after the content knowledge workshop (n = 66). Descriptive statistics and univariate analysis of variance were conducted to analyze the data of content development index scores and intratask adaptations. Frequency data across lessons by teachers and treatment conditions were employed for content development patterns. Results: There were statistically significant effects of the workshop in developing the teachers’ use of content development (p = .049) and adaptations (p = .000), but their effects varied by teacher. While the most used content development pattern by the teachers in comparison classes was an informing applying pattern, the teachers used a variety of content development patterns that included more task progressions in the experimental classes. Conclusion: It can be concluded that teachers’ instructional tasks and task adaptations could be improved through a well-designed professional development program. The findings can guide the direction of teacher education and professional development in ways to enhance teachers’ content development and adaptations.
Okseon Lee, Euichang Choi, Victoria Goodyear, Mark Griffiths, Hyukjun Son, Hyunsoo Jung, and Wonhee Lee
Although physical education (PE) teachers have increased access to digital/online continuous professional development activities, there are few robust accounts of how they engage with and experience these environments. Purpose: The purpose of this study was to examine PE teachers’ participation patterns within self-directed online PE continuous professional development activities using mobile instant messenger. Methods: Data were generated from (a) 5,246 messages exchanged in the mobile instant messenger chatroom from 281 teachers, (b) semistructured interviews with 10 teachers, and (c) 1,275 messages posted by the 10 interviewed teachers. Quantitative data were analyzed for measures of central tendency, and qualitative data were analyzed inductively. Findings: Five patterns of PE teachers’ usage of mobile instant messenger were identified: (a) ringmasters, (b) passive uploaders, (c) active uploaders, (d) requesters, and (e) bystanders. Discussion: The findings suggest that each engagement pattern illustrates the differential goals of learning, types of interaction, and forms of participation by teachers engaged in online continuous professional development.
Cindy M.T. van der Avoort, Luc J.C. van Loon, Lex B. Verdijk, Paul P.C. Poyck, Dick T.J. Thijssen, and Maria T.E. Hopman
Previous studies have used supplements to increase dietary nitrate intake in clinical populations. Little is known about whether effects can also be induced through vegetable consumption. Therefore, the aim of this study was to assess the impact of dietary nitrate, through nitrate-rich vegetables (NRV) and beetroot juice (BRJ) supplementation, on plasma nitrate and nitrite concentrations, exercise tolerance, muscle oxygenation, and cardiovascular function in patients with peripheral arterial disease. In a randomized crossover design, 18 patients with peripheral arterial disease (age: 73 ± 8 years) followed a nitrate intake protocol (∼6.5 mmol) through the consumption of NRV, BRJ, and nitrate-depleted BRJ (placebo). Blood samples were taken, blood pressure and arterial stiffness were measured in fasted state and 150 min after intervention. Each intervention was followed by a maximal walking exercise test to determine claudication onset time and peak walking time. Gastrocnemius oxygenation was measured by near-infrared spectroscopy. Blood samples were taken and blood pressure was measured 10 min after exercise. Mean plasma nitrate and nitrite concentrations increased (nitrate; Time × Intervention interaction; p < .001), with the highest concentrations after BRJ (494 ± 110 μmol/L) compared with NRV (202 ± 89 μmol/L) and placebo (80 ± 19 μmol/L; p < .001). Mean claudication onset time and peak walking time did not differ between NRV (413 ± 187 s and 745 ± 220 s, respectively), BRJ (392 ± 154 s and 746 ± 176 s), and placebo (403 ± 176 s and 696 ± 222 s) (p = .762 and p = .165, respectively). Gastrocnemius oxygenation, blood pressure, and arterial stiffness were not affected by the intervention. NRV and BRJ intake markedly increase plasma nitrate and nitrite, but this does not translate to improved exercise tolerance, muscle oxygenation, and/or cardiovascular function.
Oriana Wong, Keiko Marshall, Marc Sicova, Nanci S. Guest, Bibiana García-Bailo, and Ahmed El-Sohemy
Caffeine is commonly used to improve athletic performance across a variety of sports. Previously, the CYP1A2 gene has been shown to modify the effects of caffeine on endurance performance. The effect of caffeine on strength and power activities is unclear and may differ depending on an individual’s CYP1A2 genotype. A randomized controlled trial was used to determine whether caffeine impacts strength and power, determined by the handgrip and vertical jump tests, respectively, and whether CYP1A2 genotype modifies any effects. Competitive male athletes (age = 25 ± 4 years) completed vertical jump (n = 97), and handgrip tests (n = 102) under three conditions: 0 (placebo), 2, or 4 mg of caffeine per kilogram of body mass (in milligrams per kilogram). CYP1A2 (rs762551) genotype was determined from saliva samples. No differences between caffeine doses and placebo were observed for strength or power; however, significant Caffeine × Gene interactions were observed for all exercise tests. Individuals with the CC genotype experienced a 12.8% decrease in handgrip strength with 4 mg/kg of caffeine compared with placebo (53 ± 11 kg vs. 61 ± 17 kg, p = .02). No differences were observed in those with the AC or AA genotypes. Despite observing a significant Caffeine × Gene interaction for vertical jump performance, no differences were observed between caffeine doses and placebo for all genotypes. In summary, caffeine (4 mg/kg) worsened handgrip strength performance in those with the CC genotype, but no differences were observed in those with the AC or AA genotypes. Athletes may want to consider their CYP1A2 genotype prior to using caffeine to improve muscle strength.
Jaison L. Wynne and Patrick B. Wilson
Beer is used to socialize postexercise, celebrate sport victory, and commiserate postdefeat. Rich in polyphenols, beer has antioxidant effects when consumed in moderation, but its alcohol content may confer some negative effects. Despite beer’s popularity, no review has explored its effects on exercise performance, recovery, and adaptation. Thus, a systematic literature search of three databases (PubMed, SPORTDiscus, and Web of Science) was conducted by two reviewers. The search resulted in 16 studies that were appraised and reviewed. The mean PEDro score was 5.1. When individuals are looking to rehydrate postexercise, a low-alcohol beer (<4%) may be more effective. If choosing a beer higher in alcoholic content (>4%), it is advised to pair this with a nonalcoholic option to limit diuresis, particularly when relatively large volumes of fluid (>700 ml) are consumed. Adding Na+ to alcoholic beer may improve rehydration by decreasing fluid losses, but palatability may decrease. These conclusions are largely based on studies that standardized beverage volume, and the results may not apply equally to situations where people ingest fluids and food ad libitum. Ingesting nonalcoholic, polyphenol-rich beer could be an effective strategy for preventing respiratory infections during heavy training. If consumed in moderation, body composition and strength qualities seem largely unaffected by beer. Mixed results that limit sweeping conclusions are owed to variations in study design (i.e., hydration and exercise protocols). Future research should incorporate exercise protocols with higher ecological validity, recruit more women, prioritize chronic study designs, and use ad libitum fluid replacement protocols for more robust conclusions.