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Diego de Alcantara Borba, Eduardo da Silva Alves, João Paulo Pereira Rosa, Lucas Alves Facundo, Carlos Magno Amaral Costa, Aldo Coelho Silva, Fernanda Veruska Narciso, Andressa Silva and Marco Túlio de Mello

Background: Physical exercise plays an important role in metabolic health, especially in the insulin-like growth factor-1 (IGF-1) system. The objective of this study was to perform a systematic review and meta-analysis to evaluate the effects of a single endurance and resistance exercise session on IGF-1 serum. Methods: The systematic review was performed in SPORTDiscus, MEDLINE, PubMed, and Google Scholar databases. All analyses are based on random-effect models. The study identified 249 records of which 21 were included. Results: There was an effect of endurance exercise on total IGF-1 (P = .01), but not for free IGF-1 (P = .36). Resistance exercise similarly only affected total IGF-1 (P = .003) and not free IGF-1 (P = .37). The effect size indicated that total IGF-1 is more affected (ES = 0.81) by endurance than by resistance exercise (ES = 0.46). The present study showed that IGF-1 serum concentrations are altered by exercise type, but in conditions which are not well-defined. Conclusions: The systematic review and meta-analysis suggest that there is no determinant in serum IGF-1 changes for the exercise load characteristic. Therefore, physical exercise may be an alternative treatment to control changes in IGF-1 metabolism and blood concentration.

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Rebecca L. Krupenevich and Ross H. Miller

The causes of age-related differences in lower-extremity joint moments and powers are unknown. The purpose of this study was to determine the effects of highly physically active older adults walking with (1) a step length similar to young adults and (2) an upright trunk posture, on hip and ankle joint kinetics. The authors hypothesized that, compared with their self-selected walking mechanics, older adults would exhibit decreased hip kinetics and increased ankle kinetics when prescribed a young adult step length, and would exhibit decreased hip extension moments when maintaining an upright trunk posture during walking. A total of 12 active older adults (67 [5] y) and 13 active young adults (21 [3] y) walked at 1.3 m/s. The older adults also walked at 1.3 m/s with step lengths prescribed from height-matched young adults and, in a separate condition, walked with an upright trunk. The older adults did not display larger ankle kinetics or smaller hip kinetics in either condition compared to walking with a self-selected step length. These findings indicate that step length and trunk position do not primarily contribute to age-related differences in kinetics in highly active older adults and should serve as a starting point for investigating alternative explanations.

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E. Whitney G. Moore and Karen Weiller-Abels

Youth’s likelihood of participating in sport increases when they maintain a focus on enjoyment, learning, and effort (i.e., task goal orientation) rather than how they compare to others and norms (i.e., ego goal orientation). Achievement goal theory research consistently illustrates the significant influence of leader-created motivational climates on their participants’ goal orientation adoption. However, the influence of caring climate perceptions by highly competitive adolescent athletes on their goal orientation adoption has yet to be examined. Thus, this study assessed how competitive, adolescent soccer players’ perceptions of the climate as caring, task-, and ego-involving predicted their adoption of task and ego goal orientations. Players (N = 152, 62% female, 12–14 years of age) in the Olympic Development Program completed a survey that included measures of the caring climate, task-involving and ego-involving motivational climates, and task and ego goal orientations in soccer. Path analyses revealed males’ task goal orientation was significantly predicted by caring and task-involving climate perceptions. Females’ task goal orientation was significantly predicted by their task-involving climate perceptions. Ego goal orientation was significantly predicted by all athletes’ ego-involving climate perceptions. This is the first study to support the importance of fostering a high caring, as well as high task-involving, and low ego-involving climate when working with highly competitive adolescent athletes to keep their task goal orientation high. Research replicating this study is warranted to provide further support for these relationships longitudinally and across ages and sexes.

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Joseph O.C. Coyne, Sophia Nimphius, Robert U. Newton and G. Gregory Haff

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Bradley Fawver, Garrett F. Beatty, John T. Roman and Kevin Kurtz

The United States is one of the world’s perennial sports powers, yet the pathway to that success is littered with millions of youth athletes who either are not good enough to compete at a higher level or dropout from sport completely due to various personal, social, and organizational factors. These barriers are compounded by a win-at-all-costs mentality that pervades the U.S. sport culture and ultimately disenfranchises many youths from the opportunity to enjoy sport participation throughout their life. The authors argue that principle components in this flawed system are the lack of standardized coach education at the state and national level, weaknesses in the current curricula offered, and difficulties for aspiring coaches accessing existing training programs. In the current paper, the authors (a) briefly review the history of coach education in the United States as well as existing opportunities for coach education at the university, sport-specific, and private sectors; (b) provide a description of the strengths and weaknesses of the current coaching model; and (c) provide recommendations to improve coach education and training in the United States.

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Ivan A. Trujillo-Priego, Judy Zhou, Inge F. Werner, Weiyang Deng and Beth A. Smith

Wearable sensors are being used to measure intensity of infant physical activity across full days. The variability of infant activity intensity within and across days is important to study given the potential impact of physical activity on developmental trajectories. Using retrospective data, we analyzed the intensity of leg movements in 10 typically developing infants pre- and post-naptimes. Leg movement data were captured from 20 minutes before and after multiple events of naps across seven days for each infant. We hypothesized that leg movement intensity would be lower before a nap than after a nap potentially due to lower arousal and increased fatigue prior to attaining sleep. However, our results showed that leg movement intensity was not significantly different when comparing the 20-minute period pre- and post-naps (F(1,7) = 3.91, p = .089, ηp2=0.358). Our results are a first step in describing patterns of infant activity across days and highlights the need for further research regarding infant energy expenditure and physical activity.

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Arthur H. Bossi, Cristian Mesquida, Louis Passfield, Bent R. Rønnestad and James G. Hopker

Purpose: Maximal oxygen uptake (V˙O2max) is a key determinant of endurance performance. Therefore, devising high-intensity interval training (HIIT) that maximizes stress of the oxygen-transport and -utilization systems may be important to stimulate further adaptation in athletes. The authors compared physiological and perceptual responses elicited by work intervals matched for duration and mean power output but differing in power-output distribution. Methods: Fourteen cyclists (V˙O2max 69.2 [6.6] mL·kg−1·min−1) completed 3 laboratory visits for a performance assessment and 2 HIIT sessions using either varied-intensity or constant-intensity work intervals. Results: Cyclists spent more time at >90%V˙O2max during HIIT with varied-intensity work intervals (410 [207] vs 286 [162] s, P = .02), but there were no differences between sessions in heart-rate- or perceptual-based training-load metrics (all P ≥ .1). When considering individual work intervals, minute ventilation (V˙E) was higher in the varied-intensity mode (F = 8.42, P = .01), but not respiratory frequency, tidal volume, blood lactate concentration [La], ratings of perceived exertion, or cadence (all F ≤ 3.50, ≥ .08). Absolute changes (Δ) between HIIT sessions were calculated per work interval, and Δ total oxygen uptake was moderately associated with ΔV˙E (r = .36, P = .002). Conclusions: In comparison with an HIIT session with constant-intensity work intervals, well-trained cyclists sustain higher fractions of V˙O2max when work intervals involved power-output variations. This effect is partially mediated by an increased oxygen cost of hyperpnea and not associated with a higher [La], perceived exertion, or training-load metrics.

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Erik Trøen, Bjarne Rud, Øyvind Karlsson, Camilla Høivik Carlsen, Matthias Gilgien, Gøran Paulsen, Ola Kristoffer Tosterud and Thomas Losnegard

Purpose: To investigate how self-selected pole length (PL) of ∼84% (PL84%) compared with ∼90% (PL90%) of body height influenced performance during a 700-m time trial with undulating terrain on snow. Methods: Twenty-one cross-country skiers, 7 of whom were women, performed 4 trials at a maximal effort in a counterbalanced fashion with PL84% and PL90% separated by 20-minute breaks between trials. In trials I and II, only double poling was allowed, while in trials III and IV, skiers used self-selected classical subtechniques. Continuous speed, cyclic parameters, and heart rate were collected using microsensors in addition to a post-time-trial rating of perceived exertion (RPE). Results: The 700-m times with only double poling were significantly shorter with PL90% than PL84% (mean ± 95% confidence limits –1.6% ± 1.0%). Segment analyses showed higher speed with PL90% in uphill sections than with PL84% (3.7% ± 2.1%), with the greatest difference found for the female skiers (5.6% ± 2.9%). In contrast, on flat terrain at high skiing speeds, speed was reduced with PL90% compared with PL84% (–1.5% ± 1.4%); this was only significant for the male skiers. During free choice of classical subtechniques, PL did not influence performance in any segments, choice of subtechnique, or cycle rate during the trials. No differences in rating of perceived exertion or heart rate between PLs were found. Conclusions: PL90% improved performance in uphills at low speeds when using double poling but hindered performance on flat terrain and at higher speeds compared with self-selected PLs. Choice of PL should, therefore, be based on racecourse topography, preferred subtechniques, and the skier’s physiological and technical abilities.

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Göran Kenttä, Marte Bentzen, Kristen Dieffenbach and Peter Olusoga

High-performance (HP) coaching is a demanding profession. The proportion of woman HP coaches is reported to be in the range of 8.4–20%. Mental health concerns in elite sports have recently gained attention, but mainly focusing on athletes. Beyond coach burnout, limited attention has been given to coaches’ mental health. A recent coach burnout review included only one paper that focused exclusively on women. It has been argued that women HP coaches face greater challenges in a male-dominated coaching culture. The purpose of this study was to explore challenges experienced by women HP coaches and their perceived associations with sustainability and mental health. Thirty-seven female HP coaches participated by answering a semistructured, open-ended questionnaire. All responses were analyzed using inductive thematic analysis, which resulted in two general dimensions: challenges of working as women HP coaches and sustainability and well-being as women HP coaches. Overall, results indicate that challenges reported might be common not only for all HP coaches, but also highlight gender-specific elements. Consequently, coach retention and sustainability would benefit from more attention on well-being and mental health among HP coaches.

Open access

Lorenzo Lolli, Alan M. Batterham, Gregory MacMillan, Warren Gregson and Greg Atkinson