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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.

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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.

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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.

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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.

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Christopher R.J. Fennell and James G. Hopker

Purpose: There has been paucity in research investigating the individualization of recovery interval duration during cycling-based high-intensity interval training (HIIT). The main aim of the study was to investigate whether individualizing the duration of the recovery interval based upon the resolution of muscle oxygen consumption would improve the performance during work intervals and the acute physiological response of the HIIT session, when compared with a standardized (2:1 work recovery ratio) approach. Methods: A total of 16 well-trained cyclists (maximal oxygen consumption: 60 [7] mL·kg−1·min−1) completed 6 laboratory visits: (Visit 1) incremental exercise test, (Visit 2) determination of the individualized (IND) recovery duration, using the individuals’ muscle oxygen consumption recovery duration to baseline from a 4- and 8-minute work interval, (Visits 3–6) participants completed a 6 × 4- and a 3 × 8-minute HIIT session twice, using the IND and standardized recovery intervals. Results: Recovery duration had no effect on the percentage of the work intervals spent at >90% and >95% of maximal oxygen consumption, maximal minute power output, and maximal heart rate, during the 6 × 4- and 3 × 8-minute HIIT sessions. Recovery duration had no effect on mean work interval power output, heart rate, oxygen consumption, blood lactate, and rating of perceived exertion. There were no differences in reported session RPE between recovery durations for the 6 × 4- and 3 × 8-minute HIIT sessions. Conclusion: Individualizing HIIT recovery duration based upon the resolution of muscle oxygen consumption to baseline levels does not improve the performance of the work intervals or the acute physiological response of the HIIT session, when compared with standardized recovery duration.

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Bernhard Prinz, Dieter Simon, Harald Tschan, and Alfred Nimmerichter

Purpose: To determine aerobic and anaerobic demands of mountain bike cross-country racing. Methods: Twelve elite cyclists (7 males; V˙O2max = 73.8 [2.6] mL·min-1·kg−1, maximal aerobic power [MAP] = 370 [26] W, 5.7 [0.4] W·kg−1, and 5 females; V˙O2max = 67.3 [2.9] mL·min−1·kg−1, MAP = 261 [17] W, 5.0 [0.1] W·kg−1) participated over 4 seasons at several (119) international and national races and performed laboratory tests regularly to assess their aerobic and anaerobic performance. Power output, heart rate, and cadence were recorded throughout the races. Results: The mean race time was 79 (12) minutes performed at a mean power output of 3.8 (0.4) W·kg−1; 70% (7%) MAP (3.9 [0.4] W·kg−1 and 3.6 [0.4] W·kg−1 for males and females, respectively) with a cadence of 64 (5) rev·min−1 (including nonpedaling periods). Time spent in intensity zones 1 to 4 (below MAP) were 28% (4%), 18% (8%), 12% (2%), and 13% (3%), respectively; 30% (9%) was spent in zone 5 (above MAP). The number of efforts above MAP was 334 (84), which had a mean duration of 4.3 (1.1) seconds, separated by 10.9 (3) seconds with a mean power output of 7.3 (0.6) W·kg−1 (135% [9%] MAP). Conclusions: These findings highlight the importance of the anaerobic energy system and the interaction between anaerobic and aerobic energy systems. Therefore, the ability to perform numerous efforts above MAP and a high aerobic capacity are essential to be competitive in mountain bike cross-country.