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Timothy J.H. Lathlean, Paul B. Gastin, Stuart V. Newstead and Caroline F. Finch

Purpose: To investigate associations between load (training and competition) and wellness in elite junior Australian Football players across 1 competitive season. Methods: A prospective cohort study was conducted during the 2014 playing season in 562 players from 9 teams. Players recorded their training and match intensities according to the session-rating-of-perceived-exertion (sRPE) method. Based on sRPE player loads, a number of load variables were quantified, including cumulative load and the change in load across different periods of time (including the acute-to-chronic load ratio). Wellness was quantified using a wellness index including sleep, fatigue, soreness, stress, and mood on a Likert scale from 1 to 5. Results: Players spent an average of 85 (21) min in each match and 65 (31) min per training session. Average match loads were 637 (232) arbitrary units, and average training loads were 352 (233) arbitrary units. Over the 24 wk of the 2014 season, overall wellness had a significant linear negative association with 1-wk load (B = −0.152; 95% confidence interval, −0.261 to −0.043; P = .006) and an inverse U-curve relationship with session load (B = −0.078; 95% confidence interval, 0.143 to 0.014; P = .018). Mood, stress, and soreness were all found to have associations with load. Conclusions: This study demonstrates that load (within a session and across the week) is important in managing the wellness of elite junior Australian Football players. Quantifying loads and wellness at this level will help optimize player management and has the potential to reduce the risk of adverse events such as injury.

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Dean Norris, David Joyce, Jason Siegler, James Clock and Ric Lovell

Purpose: This study assessed the utility of force–time characteristics from the isometric midthigh pull (IMTP) as a measure of neuromuscular function after elite-level Australian rules football matches. It was hypothesized that rate characteristics of force development would demonstrate a different response magnitude and recovery time course than peak force measurements. Methods: Force–time characteristics of the IMTP (peak force, 0- to 50-ms rate of force development [RFD], 100- to 200-ms RFD) were collected at 48 (G+2), 72 (G+3), and 96 h (G+4) after 3 competitive Australian rules football matches. Results: Meaningful reductions (>75% of the smallest worthwhile change) were observed at G+2, G+3, and G+4 for RFD 0–50 milliseconds (−25.8%, −17.5%, and −16.9%) and at G+2 and G+3 for RFD 100–200 milliseconds (−15.7% and −11.7%). No meaningful reductions were observed for peak force at any time point (G+2 −4.0%, G+3 −3.9%, G+4 −2.7%). Higher week-to-week variation was observed for RFD 0–50 milliseconds (G+2 17.1%, G+3 27.2%, G+4 19.3%) vs both RFD 100–200 milliseconds (G+2 11.3%, G+3 11.5%, G+4 7.2%) and peak force (G+2 4.8%, G+3 4.4%, G+4 8.4%). Conclusions: These findings highlight the potential use of rate characteristics from the IMTP as measures of neuromuscular function in elite sport settings, and in particular RFD 100–200 milliseconds due to its higher reliability. Interestingly, peak force collected from the IMTP was not meaningfully suppressed at any time point after elite Australian rules football match play. This suggests that rate characteristics from IMTP may provide more sensitive and valuable insight regarding neuromuscular function recovery kinetics than peak measures.

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Paul F.J. Merkes, Paolo Menaspà and Chris R. Abbiss

Purpose: To assess the influence of seated, standing, and forward-standing cycling sprint positions on aerodynamic drag (CdA) and the reproducibility of a field test of CdA calculated in these different positions. Methods: A total of 11 recreational male road cyclists rode 250 m in 2 directions at around 25, 32, and 40 km·h−1 and in each of the 3 positions, resulting in a total of 18 efforts per participant. Riding velocity, power output, wind direction and velocity, road gradient, temperature, relative humidity, and barometric pressure were measured and used to calculate CdA using regression analysis. Results: A main effect of position showed that the average CdA of the 2 d was lower for the forward-standing position (0.295 [0.059]) compared with both the seated (0.363 [0.071], P = .018) and standing positions (0.372 [0.077], P = .037). Seated and standing positions did not differ from each other. Although no significant difference was observed in CdA between the 2 test days, a poor between-days reliability was observed. Conclusion: A novel forward-standing cycling sprint position resulted in 23% and 26% reductions in CdA compared with a seated and standing position, respectively. This decrease in CdA could potentially result in an important increase in cycling sprint velocity of 3.9–4.9 km·h−1, although these results should be interpreted with caution because poor reliability of CdA was observed between days.

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Jade A.Z. Haycraft, Stephanie Kovalchik, David B. Pyne and Sam Robertson

Purpose: To establish levels of association between physical fitness and match activity profiles of players in the Australian Football League (AFL) participation pathway. Methods: Players (N = 287, range 10.9–19.1 y) were assessed on 20-m sprint, AFL agility, vertical jump and running vertical jump, 20-m multistage fitness test (MSFT), and Athletic Abilities Assessment. Match activity profiles were obtained from global positioning system measures: relative speed, maximal velocity, and relative high-speed running. Results: Correlational analyses revealed moderate relationships between sprint (r = .32–.57, P ≤ .05) and jump test scores (r = .34–.78, P ≤ .05) and match activity profiles in Local U12, Local U14, National U16, and National U18s, except jump tests in National U18s. AFL agility was also moderate to strongly associated in Local U12, Local U14, Local U18, and National U16s (r = .37–.87, P ≤ .05) and strongly associated with relative speed in Local U18s (r = .84, P ≤ .05). Match relative speed and high-speed running were moderate to strongly associated with 20-m MSFT in Local U14, Local U18, and National U18s (r = .41–.95, P ≤ .05) and Athletic Abilities Assessment in Local U12 and Local U18s (r = .35–.67, P ≤ .05). Match activity profile demands increased between Local U12 and National U16s, then plateaued. Conclusions: Physical fitness relates more strongly to match activity profiles in younger adolescent and national-level players. Recruiters should consider adolescent physical fitness and match activity profiles as dynamic across the AFL participation pathway.

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Kerri L. Vasold, Andrew C. Parks, Deanna M.L. Phelan, Matthew B. Pontifex and James M. Pivarnik

Research comparing portable body composition methods, such as bioelectrical impedance analysis (BIA), to air displacement plethysmography (ADP) is limited. We assessed reliability and validity of predicting fat-free mass (FFM) by the RJL, Omron, and Tanita BIA machines using ADP via BodPod as a criterion. FFM (kg) was assessed twice in college students (N = 77, 31 males and 46 females; age = 19.1 ± 1.2 years) using ADP, RJL, Omron, and Tanita BIAs. Reliability was assessed using analysis of variance to obtain an intraclass correlation statistic (Rxx). Validity was assessed using Pearson correlation (r) coefficient. FFM averaged 75.6 ± 9.4 kg in men and 59.8 ± 7.6 kg in women. Reliability was high in both genders RJL (Rxx = .974–.994), Omron (Rxx = .933–.993), and Tanita (Rxx = .921–.991). Validity within males was also high: RJL (r = .935), Omron (r = .942), and Tanita (r = .934), and only slightly lower in females: RJL (r = .924), Omron (r = .897), and Tanita (r = .898). The RJL, Omron, and Tanita BIA machines appear to be both reliable and valid for predicting FFM of male and female college students. Therefore, any of these three BIA devices is appropriate to use for body composition assessment in a healthy adult population.

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James Wright, Thomas Walker, Scott Burnet and Simon A. Jobson

Purpose: To (1) evaluate agreement between the PowerTap P1 (P1) pedals and the Lode Excalibur Sport cycle ergometer, (2) investigate the reliability of the P1 pedals between repeated testing sessions, and (3) compare the reliability and validity of the P1 pedals before (P10) and after (P1100) ∼100 h of use. Methods: Ten participants completed four 5-min submaximal cycling bouts (100, 150, 200, and 250 W), a 2-min time trial, and two 10-s all-out sprints on 2 occasions. This protocol was repeated after 15 mo and ∼100 h of use. Results: Significant differences were seen between the P10 pedals and the Lode Excalibur Sport at 100 W (P = .006), 150 W (P = .006), 200 W (P = .001), and 250 W (P = .006) and during the all-out sprints (P = .020). After ∼100 h of use, the P1100 pedals did not significantly differ from the Lode Excalibur Sport at 100 W (P = .799), 150 W (P = .183), 200 W (P = .289), and 250 W (P = .183), during the 2-min time trial (P = .583), or during the all-out sprints (P = .412). The coefficients of variation for the P10 and P1100 ranged from 0.6% to 1.3% and 0.5% to 2.0%, respectively, during the submaximal cycling bouts. Conclusion: The P1 pedals provide valid data after ∼100 h of laboratory use. Furthermore, the pedals provide reliable data during submaximal cycling, even after prolonged use.

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Adam Beard, John Ashby, Ryan Chambers, Franck Brocherie and Grégoire P. Millet

Purpose: To investigate the effects of repeated-sprint training in hypoxia vs in normoxia on world-level male rugby union players’ repeated-sprint ability (RSA) during an international competition period. Methods: A total of 19 players belonging to an international rugby union senior male national team performed 4 sessions of cycling repeated sprints (consisting of 3 × eight 10-s sprints with 20 s passive recovery) either in normobaric hypoxia (RSH, 3000 m; n = 10) or in normoxia (RSN, 300 m; n = 9) over a 2-wk period. Before and after the training intervention, RSA was evaluated using a cycling repeated-sprint test (6 × 10-s maximal sprint and 20-s passive recovery) performed in normoxia. Results: Significant interaction effects (all P < .05, ηp2>.37) between condition and time were found for RSA-related parameters. Compared with Pre, maximal power significantly improved at Post in RSH (12.84 [0.83] vs 13.63 [1.03] W·kg−1, P < .01, ηp2=.15) but not in RSN (13.17 [0.89] vs 13.00 [1.01] W·kg−1, P = .45, ηp2=.01). Mean power was also significantly enhanced from Pre to Post in RSH (11.15 [0.58] vs 11.86 [0.63] W·kg−1, P < .001, ηp2=.26), whereas it remained unchanged in RSN (11.54 [0.61] vs 11.75 [0.65] W·kg−1, P = .23, ηp2=.03). Conclusion: As few as 4 dedicated specific RSH sessions were beneficial to enhance repeated power production in world-level rugby union players. Although the improvement from RSA to game behavior remains unclear, this finding appears to be of practical relevance as only a short preparation window is available prior to international rugby union games.

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Gustavo Monnerat, Alex S. Maior, Marcio Tannure, Lia K.F.C. Back and Caleb G.M. Santos

Purpose: Soccer is one of the most popular sports worldwide, a physical activity of great physiological demand and complexity. Currently, numerous trials involving physiological responses such as hypertrophy, energy expenditure, vasodilation, cardiac output, VO2max, and recovery have supported the possibility of genomic predictors’ affecting performance. In a complementary way to association studies with single nucleotide polymorphisms (SNPs), the objective was to evaluate if the use of population genetics data from human-genomics databases can provide information for a better understanding of the relationship between heritability and sport performance. Methods: The study included 25 healthy male professional soccer players (25.5 [4.3] y, 177.4 [6.4] cm, 76.4 [6.4] kg, body fat 10.5% [4.3%]) from the Brazilian first-division soccer club. Anthropometric measurements and field and isokinetic tests were performed to evaluate performance and physiologic parameters of subjects. Moreover, 10 genetic polymorphisms previously related to performance were genotyped. The genotypes of the same polymorphisms were obtained for 2504 individuals from the populations deposited in the 1000 Genomes database. A principal-component analysis and matrix genetic-distances approach (Fst) were evaluated. Results: As expected, the admixture Brazilian population has numerous genetic similarities with the European and American populations from genomic databases. Although the African component is absolutely recognized in genomes from the Brazilian population, using the specific performance-related SNPs, surprisingly the African population was one of the most genetically distant of the players (P < .00001). Conclusions: The early results suggest a selective pressure on genes of elite soccer players, possibly related simultaneously to physical-performance, environmental, cognitive, and sociocultural aspects.

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Benjamin G. Serpell, Barry G. Horgan, Carmen M.E. Colomer, Byron Field, Shona L. Halson and Christian J. Cook

Purpose: To examine changes in, and relationships between, sleep quality and quantity, salivary testosterone, salivary cortisol, testosterone-to-cortisol ratio (T:C), and self-reported muscle soreness during a residential-based training camp in elite rugby players. Methods: Nineteen male rugby players age 26.4 (3.9) years, height 186.0 (9.4) cm, and weight 104.1 (13.4) kg (mean [SD]) participated in this study. Wrist actigraphy devices were worn for 8 nights around a 4-d training camp (2 nights prior, during, and 2 nights after). Sleep-onset latency, sleep duration, sleep efficiency, and waking time were measured. Participants provided saliva samples during camp on waking and again 45 min later, which were then assayed for testosterone and cortisol levels. They also rated their general muscle soreness daily. Results: Little variation was observed for sleep quality and quantity or testosterone. However, significant differences were observed between and within days for cortisol, T:C, and muscle soreness (P < .001). Few relationships were observed for sleep and hormones; the strongest, an inverse relationship for sleep efficiency and T:C (r = −.372, P < .01). Conclusions: There may be no clear and useful relationship between sleep and hormone concentration in a short-term training camp context, and measures of sleep and testosterone and cortisol should be interpreted with caution because of individual variation. Alterations in hormone concentration, particularly cortisol, may be affected by other factors including anticipation of the day ahead. This study adds to our knowledge that changes in hormone concentration are individual and context specific.

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Bridget Ellen Philippa Bourke, Dane Francis Baker and Andrea Jane Braakhuis

Social media contains a wealth of nutrition information and proposes a cost-effective, highly engaging platform to deliver nutrition information to athletes. This study used an online questionnaire to determine whether New Zealand athletes are using social media as a source of nutrition information and to understand perceptions of social media as a nutrition resource. Quantitative data were analyzed using t tests, chi-squared tests, and logistic regression analysis. Inductive thematic analysis was adopted for the qualitative data. From the 306 athletes who completed the questionnaire, 65% reported social media use for nutrition purposes in the past 12 months. Social media use was predicted by both athlete status and gender. Female athletes were more likely to have used social media for nutrition purposes (odds ratio = 2.7, 95% confidence interval [1.52, 4.62], p = .001) than males. Elite athletes were less likely to have used social media for nutrition (odds ratio = 0.44, 95% confidence interval [0.24, 0.83], p = .011) than recreational athletes. Athletes commonly used social media for practical nutrition purposes, including recipes and information about restaurants/cafes. Perceived advantages of social media as a nutrition resource included ease of access, well-presented information, personal connectedness, and information richness. Athletes’ primary concern for obtaining nutrition information from social media was information unreliability.