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Naoya Takei, Katsuyuki Kakinoki, Olivier Girard and Hideo Hatta

Background: Training in hypoxia versus normoxia often induces larger physiological adaptations, while this does not always translate into additional performance benefits. A possible explanation is a reduced oxygen flux, negatively affecting training intensity and/or volume (decreasing training stimulus). Repeated Wingates (RW) in normoxia is an efficient training strategy for improving both physiological parameters and exercise capacity. However, it remains unclear whether the addition of hypoxia has a detrimental effect on RW performance. Purpose: To test the hypothesis that acute moderate hypoxia exposure has no detrimental effect on RW, while both metabolic and perceptual responses would be slightly higher. Methods: On separate days, 7 male university sprinters performed 3 × 30-s Wingate efforts with 4.5-min passive recovery in either hypoxia (FiO2: 0.145) or normoxia (FiO2: 0.209). Arterial oxygen saturation was assessed before the first Wingate effort, while blood lactate concentration and ratings of perceived exertion were measured after each bout. Results: Mean (P = .92) and peak (P = .63) power outputs, total work (P = .98), and the percentage decrement score (P = .25) were similar between conditions. Arterial oxygen saturation was significantly lower in hypoxia versus normoxia (92.0% [2.8%] vs 98.1% [0.4%], P < .01), whereas blood lactate concentration (P = .78) and ratings of perceived exertion (P = .51) did not differ between conditions. Conclusion: In sprinters, acute exposure to moderate hypoxia had no detrimental effect on RW performance and associated metabolic and perceptual responses.

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Helene Pedersen, Atle Hole Saeterbakken, Markus Vagle, Marius Steiro Fimland and Vidar Andersen

Purpose: The Nordic hamstring exercise (NHE) has been shown to considerably reduce hamstring injuries among soccer players. However, as the load in the NHE is the person’s own bodyweight, it is a very heavy exercise and difficult to individualize. The flywheel inertial leg curl (FLC) could be an alternative since the eccentric overload is based on the amount of work produced in the concentric movement. Therefore, the primary aim of this study was to compare the activation in the hamstrings at long muscle lengths in the NHE and the FLC in amateur soccer players. Methods: Fifteen male amateur soccer players performed 5 repetitions in each exercise in a randomized and counterbalanced order. The concentric and eccentric movements were divided into lower and upper phases. Surface EMG was measured distally, proximally, and in the middle, at both muscles. Results: In the lower phase in the eccentric movement, there were no significant differences between the 2 exercises (P = .101–.826). In the lower concentric movement, the FLC led to higher activation in all parts of both the biceps femoris (31%–52%, P < .001) and the semitendinosus (20%–35%, P = .001–.023). Conclusion: Both exercises activated the hamstrings similarly at long muscle lengths during eccentric contractions (Nordic hamstring, nonsignificantly higher). However, when performing concentric contractions, the FLC induced higher activations. Therefore, the FLC could be a useful alternative to the NHE and particularly suitable for weaker athletes before progressing to NHE.

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Filippo Dolci, Andrew E. Kilding, Tania Spiteri, Paola Chivers, Ben Piggott, Andrew Maiorana and Nicolas H. Hart

Purpose: To evaluate the reliability of new change-of-direction-economy tests (assessing energetic efficiency when performing continuous shuttle runs) compared with common running-economy tests in soccer players Methods: Sixteen subelite, male soccer players were recruited to perform a testing battery involving running economy (RE), 10-m shuttle-running economy (SRE10), and 20-m shuttle-running economy (SRE20) at 8.4 km·h−1 mean speed on 2 different days within 48 hours. SRE10 and SRE20 consisted of continuous shuttle runs interspersed with 180° directional changes. During the RE, SRE20, and SRE10 tests, respiratory exchange ratio and oxygen uptake were collected and used to calculate the movement-economy values over any running condition as oxygen cost and energetic cost. The secondary variables (carbon dioxide production, heart rate, minute ventilation, and blood lactate) were also monitored during all tests. Results: Depending on expression (oxygen cost or energetic cost), reliability was established for RE (CV: 5.5%–5.8%; ICC = .77–.88), SRE10 (CV: 3.5%–3.8%; ICC = .78–.96), and SRE20 (CV: 3.5%–3.8%; ICC = .66–.94). All secondary physiological variables reported good reliability (CV < 10%), except for blood lactate (CV < 35.8). The RE, SRE10, and SRE20 tests show good reliability in soccer players, whereas blood lactate has the highest variability among physiological variables during the economy tests. Conclusion: The assessment of change-of-direction economy through performing 20- and 10-m shuttle runs is reliable and can be applied to evaluate soccer players’ energetic movement efficiency under more soccer-specific running conditions.

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Rebecca Fernandes, Chris Bishop, Anthony N. Turner, Shyam Chavda and Sean J. Maloney

Purpose: Currently, it is unclear which physical characteristics may underpin the change of direction deficit (COD-D). This investigation sought to determine if momentum, speed-, and jump-based measures may explain variance in COD-D. Methods: Seventeen males from a professional soccer academy (age, 16.76 [0.75] y; height, 1.80 [0.06] m; body mass, 72.38 [9.57] kg) performed 505 tests on both legs, a 40-m sprint, and single-leg countermovement and drop jumps. Results: The regression analyses did not reveal any significant predictors for COD-D on either leg. “Large” relationships were reported between the COD-D and 505 time on both limbs (r = .65 to .69; P < .01), but COD-D was not associated with linear momentum, speed-, or jump-based performances. When the cohort was median split by COD-D, the effect sizes suggested that the subgroup with the smaller COD-D was 5% faster in the 505 test (d = −1.24; P < .001) but 4% slower over 0–10 m (d = 0.79; P = .33) and carried 11% less momentum (d = −0.81; P = .17). Conclusion: Individual variance in COD-D may not be explained by speed- and jump-based performance measures within academy soccer players. However, when grouping athletes by COD-D, faster athletes with greater momentum are likely to display a larger COD-D. It may, therefore, be prudent to recommend more eccentric-biased or technically focused COD training in such athletes and for coaches to view the COD action as a specific skill that may not be represented by performance time in a COD test.

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Ann Pulling Kuhn, Russell L. Carson, Aaron Beighle and Darla M. Castelli

Purpose: This study examined changes in physical education teachers’ psychosocial perspectives after participating in a yearlong professional development about Comprehensive School Physical Activity Programming. Method: Twenty-three intervention teachers attended a workshop in Year 1 and received one academic year of technical assistance and mentorship, and 30 control teachers only attended a workshop in Year 2. Both groups completed pre- and post-self-reported measures on teacher efficacy, work engagement, and affective commitment. Results: At posttest, intervention teachers reported significantly higher levels of affective commitment, and a significant positive relationship was revealed between affective commitment and the degree to which before-school physical activity was implemented. More experienced teachers (>20 years) reported significantly higher levels of the work engagement subscale of vigor at posttest. Discussion/Conclusion: Participating in a Comprehensive School Physical Activity Program professional development may positively influence teachers’ job commitment levels and invigorate more experienced teachers, which may relate to Comprehensive School Physical Activity Program implementation.

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Jamie Taylor and Dave Collins

There appears to be general agreement that interaction with significant challenge should be a central feature of the development pathways for future high performers. There is, however, far less clarity about how such programs should be designed and delivered against core psychological principles. Accordingly, the purpose of this paper is to offer guidelines for talent development practitioners seeking to offer athletes the opportunity to maximize their growth and development. The authors propose that genuinely developmental experiences will likely offer a level of emotional disturbance and, as a result, more fully engage performers, prompting self and other facilitated reflection, and motivate future action. Furthermore, there is a necessity for these experiences and their follow-up, to be managed in a coherent manner and integrated with existing skills, experience, and future performance aims. In highlighting these issues, the authors offer recommendations for talent development coaches, managers, psychologists, and parents of athletes.

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Tan Zhang, Anqi Deng and Ang Chen

Purpose: Guided by the declarative−procedural knowledge framework, the study attempts to identify middle school students’ declarative (knowing what) and procedural (knowing how) fitness knowledge and the relationship between the two. Methods: A sample of students (n = 291, age 11–14 years) from 24 middle schools took a grade-relevant standardized knowledge test on declarative fitness knowledge and received a semistructured interview designed to clarify their declarative and procedural knowledge. Results: Most students were lacking in procedural knowledge to conduct fitness-enhancing physical activities. A few students who had mastered declarative fitness knowledge demonstrated a high level of procedural knowledge consistent with personal fitness goals. Discussion: The findings suggest that incapability to engage in fitness-enhancing physical activities could be a result of lacking procedural fitness knowledge. Future school-based interventions may prioritize procedural knowledge learning for actual physical activity participation.

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Evelyne Felber Charbonneau, Martin Camiré and Pierre-Nicolas Lemyre

Coaching is a global profession and coaches play a central role in enhancing the performance of millions of athletes worldwide. In the 21st century, the global mobility of coaches has increased, with many coaches taking advantage of opportunities to coach abroad. Norway leads the all-time Winter Olympics medals table (i.e., 368 medals), and with most of these medals coming from skiing disciplines, Norway represents a skiing hotbed that attracts ski coaches from other parts of the world. The purpose of the study was to examine ski coaches’ motives for and experiences of expatriation to coach in Norway. Five North American alpine ski coaches (four males and one female) were individually interviewed (M = 77 min, SD = 24.94), with the data examined using interpretative phenomenological analysis. Motives for expatriation included having a passion for skiing, challenging oneself, experiencing a new sport culture, and maintaining relationships. Upon arriving in Norway, coaches mentioned experiencing challenges with the Norwegian sport system, language, pressure from parents and the media, and being far from friends and family. Once acclimated, coaches discussed the benefits of expatriation that included the Norwegian work ethic, family-centric lifestyle, and popularity of skiing.

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Matheus Barbalho, Ana Francisca Rozin Kleiner, Bianca Callegari, Ramon Costa de Lima, Givago da Silva Souza, Anselmo de Athayde Costa e Silva and Victor Silveira Coswig

Background: Jumps are important evaluation tools for muscle strength and power and for interlimb asymmetries. Different jump tests are well related to athletic performance, prediction of injury risk, and common motor gestures of several sports such as soccer. Low-cost mobile applications (apps) have gained popularity for this measure. The authors hypothesized that the My Jump 2 app would be a valid tool to assess drop-jump performance and interlimb asymmetry in soccer players. Methods: Eleven male soccer players took part in this study (18.2 [1.3] y, 69.9 [9.5] kg, 174 [6.6] cm). The athletes performed each test twice on a force plate (gold-standard method), while the jumps were recorded through the mobile app. Measures with the My Jump 2 app were applied by 2 evaluators, independently and in duplicate (interrater and intrarater reliability). The agreement analysis between both evaluations was done using an intraclass correlation coefficient and Bland–Altman plots. Results: Compared with the force platform, the app tested showed excellent reliability for the drop jump’s flight time and interlimb asymmetry (intraclass correlation coefficient > .98). For interlimb contact-time asymmetry, the values were 18.4 (9.9) and 19.1 (9.9) milliseconds for the My Jump 2 app and the force platform, respectively (P = .88). For flight-time asymmetries, the values were 389.7 (114.3) and 396.8 (112.5) milliseconds for the My Jump 2 app and the force platform, respectively (P = .88). Conclusion: The My Jump 2 app is a valid tool to assess drop-jump and interlimb asymmetry in soccer players.

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João Paulo Limongi França Guilherme, Ekaterina A. Semenova, Hirofumi Zempo, Gabriel L. Martins, Antonio H. Lancha Junior, Eri Miyamoto-Mikami, Hiroshi Kumagai, Takuro Tobina, Keisuke Shiose, Ryo Kakigi, Takamasa Tsuzuki, Noriko Ichinoseki-Sekine, Hiroyuki Kobayashi, Hisashi Naito, Oleg V. Borisov, Elena S. Kostryukova, Nikolay A. Kulemin, Andrey K. Larin, Edward V. Generozov, Noriyuki Fuku and Ildus I. Ahmetov

Purpose: To replicate previous genome-wide association study identified sprint-related polymorphisms in 3 different cohorts of top-level sprinters and to further validate the obtained results in functional studies. Methods: A total of 240 Japanese, 290 Russians, and 593 Brazilians were evaluated in a case-control approach. Of these, 267 were top-level sprint/power athletes. In addition, the relationship between selected polymorphisms and muscle fiber composition was evaluated in 203 Japanese and 287 Finnish individuals. Results: The G allele of the rs3213537 polymorphism was overrepresented in Japanese (odds ratio [OR]: 2.07, P = .024) and Russian (OR: 1.93, P = .027) sprinters compared with endurance athletes and was associated with an increased proportion of fast-twitch muscle fibers in Japanese (P = .02) and Finnish (P = .041) individuals. A meta-analysis of the data from 4 athlete cohorts confirmed that the presence of the G/G genotype rather than the G/A+A/A genotypes increased the OR of being a sprinter compared with controls (OR: 1.49, P = .01), endurance athletes (OR: 1.79, P = .001), or controls + endurance athletes (OR: 1.58, P = .002). Furthermore, male sprinters with the G/G genotype were found to have significantly faster personal times in the 100-m dash than those with G/A+A/A genotypes (10.50 [0.26] vs 10.76 [0.31], P = .014). Conclusion: The rs3213537 polymorphism found in the CPNE5 gene was identified as a highly replicable variant associated with sprinting ability and the increased proportion of fast-twitch muscle fibers, in which the homozygous genotype for the major allele (ie, the G/G genotype) is preferable for performance.