Sofie Koch, Jens Troelsen, Samuel Cassar and Charlotte Skau Pawlowski
Purpose: In 2014, the Danish Government introduced a new public school reform, which included implementation of 45 min of daily physical activity (PA) within the academic classroom curriculum. The purpose of the present study was to explore school staff’s perceived barriers to implementation of a national PA policy. Method: A mixed-methods approach using a questionnaire and semistructured interviews was conducted. A total of 198 teachers and 26 school management team members (principals, deputy principals, and leading teachers) from 31 schools completed a questionnaire, and 11 school management team members were interviewed. The socioecological model was used as a theoretical framework to examine the results. Results: A total of 15 different barriers were identified and reflected within all levels of the socioecological model. Facilities, motivation, and time were the most prominent barriers identified. Conclusion: Development and deployment of a national PA policy needs to be done in cooperation with consumers from all levels within the socioecological model to ensure successful implementation.
Steve H. Faulkner and Philippa Jobling
Purpose: Cycling time trials (TTs) are characterized by riders’ adopting aerodynamic positions to lessen the impact of aerodynamic drag on velocity. The optimal performance requirements for TTs likely exist on a continuum of rider aerodynamics versus physiological optimization, yet there is little empirical evidence to inform riders and coaches. The aim of the present study was to investigate the relationship between aerodynamic optimization, energy expenditure, heat production, and performance. Methods: Eleven trained cyclists completed 5 submaximal exercise tests followed by a TT. Trials were completed at hip angles of 12° (more horizontal), 16°, 20°, 24° (more vertical), and their self-selected control position. Results: The largest decrease in power output at anaerobic threshold compared with control occurred at 12° (−16  W, P = .03; effect size [ES] = 0.8). There was a linear relationship between upper-body position and heat production (R 2 = .414, P = .04) but no change in mean body temperature, suggesting that, as upper-body position and hip angle increase, convective and evaporative cooling also rise. The highest aerodynamic–physiological economy occurred at 12° (384  W·C d A −1·L−1·min−1, ES = 0.4), and the lowest occurred at 24° (338  W·C d A −1·L−1·min−1, ES = 0.7), versus control (367  W·C d A −1·L−1·min−1). Conclusion: These data suggest that the physiological cost of reducing hip angle is outweighed by the aerodynamic benefit and that riders should favor aerodynamic optimization for shorter TT events. The impact on thermoregulation and performance in the field requires further investigation.
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.
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.
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.
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.
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.
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.
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.