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Daniel Martínez-Silván, Jaime Díaz-Ocejo and Andrew Murray

Purpose:

To analyze the influence of training exposure and the utility of self-report questionnaires on predicting overuse injuries in adolescent endurance athletes.

Methods:

Five adolescent male endurance athletes (15.7 ± 1.4 y) from a full-time sports academy answered 2 questionnaires (Recovery Cue; RC-q and Oslo Sports Trauma Research questionnaire; OSTRC-q) on a weekly basis for 1 season (37 wk) to detect signs of overtraining and underrecovery (RC-q) and early symptoms of lower-limb injuries (OSTRC-q). All overuse injuries were retrospectively analyzed to detect which variations in the questionnaires in the weeks preceding injury were best associated. Overuse incidence rates were calculated based on training exposure.

Results:

Lower-limb overuse injuries accounted for 73% of total injuries. The incidence rate for overuse training-related injuries was 10 injuries/1000 h. Strong correlations were observed between individual running exposure and overuse injury incidence (r 2 = .66), number of overuse injuries (r 2 = .69), and days lost (r 2 = .66). A change of 20% or more in the RC-q score in the preceding week was associated with 67% of the lower-limb overuse injuries. Musculoskeletal symptoms were only detected in advance by the OSTRC-q in 27% of the episodes.

Conclusion:

Training exposure (especially running exposure) was shown to be related to overuse injuries, suggesting that monitoring training load is a key factor for injury prevention. Worsening scores in the RC-q (but not the OSTRC) may be an indicator of overuse injury in adolescent endurance runners when used longitudinally.

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Billy T. Hulin, Tim J. Gabbett, Rich D. Johnston and David G. Jenkins

Purpose: To determine (1) how change-of-direction (COD) workloads influence PlayerLoad (PL) variables when controlling total distance covered and (2) relationships among collision workloads and PL variables during rugby league match play. Methods: Participants completed 3 protocols (crossover design) consisting of 10 repetitions of a 60-m effort in 15 s. The difference between protocols was the COD demands required to complete 1 repetition: no COD (straight line), 1° × 180° COD, or 3° × 180° COD. During rugby league matches, relationships among collision workloads, triaxial vector-magnitude PlayerLoad (PLVM), anteroposterior + mediolateral PL (PL2D), and PLVM accumulated at locomotor velocities below 2 m·s−1 (ie, PLSLOW) were examined using Pearson correlations (r) with coefficients of determination (R2). Results: Comparing 3° × 180° COD to straight-line drills, PLVM·min−1 (d = 1.50 ± 0.49, large, likelihood = 100%, almost certainly), PL2D·min−1 (d = 1.38 ± 0.53, large, likelihood = 100%, almost certainly), and PLSLOW·min−1 (d = 1.69 ± 0.40, large, likelihood = 100%, almost certainly) were greater. Collisions per minute demonstrated a distinct (ie, R2 < .50) relationship from PLVM·min−1 (R2 = .30, r = .55) and PL2D·min−1 (R2 = .37, r = .61). Total distance per minute demonstrated a very large relationship with PLVM·min−1 (R2 = .62, r = .79) and PL2D·min−1 (R2 = .57, r = .76). Conclusions: PL variables demonstrate (1) large increases as COD demands intensify, (2) separate relationships from collision workloads, and (3) moderate to very large relationships with total distance during match play. PL variables should be used with caution to measure collision workloads in team sport.

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Gil Rodas, Lourdes Osaba, David Arteta, Ricard Pruna, Dolors Fernández and Alejandro Lucia

Purpose: The authors investigated the association between risk of tendinopathies and genetic markers in professional team sports. Methods: The authors studied 363 (mean [SD]; 25 [6] y, 89% male) elite players (soccer, futsal, basketball, handball, and roller hockey) from a top-level European team (FC Barcelona, Spain). Of 363, 55% (cases) had experienced 1+ episodes of tendinopathy during 2008–2018 and 45% (controls) remained injury free. The authors first examined the association between single-nucleotide polymorphisms (SNPs) and tendinopathy risk in a hypothesis-free case-control genome-wide association study (495,837 SNPs) with additional target analysis of 58 SNPs that are potential candidates to influence tendinopathy risk based on the literature. Thereafter, the authors augmented the SNP set by performing synthetic variant imputation (1,419,369 SNPs) and then used machine learning-based multivariate modeling (support vector machine and random forest) to build a reliable predictive model. Results: Suggestive association (P < 10−5) was found for rs11154027 (gap junction alpha 1), rs4362400 (vesicle amine transport 1-like), and rs10263021 (contactin-associated protein-like 2). Carriage of 1+ variant alleles for rs11154027 (odds ratio = 2.11; 95% confidence interval, 1.07–4.19, P = 1.01 × 10−6) or rs4362400 (odds ratio = 1.98; 95% confidence interval, 1.05–3.73, P = 9.6 × 10−6) was associated with a higher risk of tendinopathy, whereas an opposite effect was found for rs10263021 (odds ratio = 0.42; 95% confidence interval, 0.20–0.91], P = 4.5 × 10−6). In the modeling approach, one of the most robust SNPs was rs10477683 in the fibrillin 2 gene encoding fibrillin 2, a component of connective tissue microfibrils involved in elastic fiber assembly. Conclusions : The authors have identified previously undescribed genetic predictors of tendinopathy in elite team sports athletes, notably rs11154027, rs4362400, and rs10263021.

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Jeanne F. Nichols, Mitchell J. Rauh, Michelle T. Barrack, Hava-Shoshana Barkai and Yael Pernick

The authors’ purpose was to determine the prevalence and compare associations of disordered eating (DE) and menstrual irregularity (MI) among high school athletes. The Eating Disorder Examination Questionnaire (EDE-Q) and a menstrual-history questionnaire were administered to 423 athletes (15.7 ± 1.2 y, 61.2 ± 10.2 kg) categorized as lean build (LB; n = 146) or nonlean build (NLB; n = 277). Among all athletes, 20.0% met the criteria for DE and 20.1% for MI. Although the prevalence of MI was higher in LB (26.7%) than NLB (16.6%) athletes (P = 0.01), no differences were found for DE. For both sport types, oligo/amenorrheic athletes consistently reported higher EDE-Q scores than eumenorrheic athletes (P < 0.05). Athletes with DE were over 2 times as likely (OR = 2.3, 95%CI: 1.3, 4.2) to report oligo/amenorrhea than athletes without DE. These data establish an association between DE and MI among high school athletes and indicate that LB athletes have more MI but not DE than NLB athletes.

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Jeffrey M. Willardson, Fabio E. Fontana and Eadric Bressel

Purpose:

To compare core muscle activity during resistance exercises performed on stable ground vs. the BOSU Balance Trainer.

Methods:

Twelve trained men performed the back squat, dead lift, overhead press, and curl lifts. The activity of the rectus abdominis, external oblique abdominis, transversus abdominis/internal oblique abdominis, and erector spinae muscles was assessed. Subjects performed each lift under three separate conditions including standing on stable ground with 50% of a 1-RM, standing on a BOSU Balance Trainer with 50% of a 1-RM, and standing on stable ground with 75% of a 1-RM.

Results:

Significant differences were noted between the stable 75% of 1-RM and BOSU 50% of 1-RM conditions for the rectus abdominis during the overhead press and transversus abdominis/internal oblique abdominis during the overhead press and curl (P < .05). Conversely, there were no significant differences between the stable 75% of 1-RM and BOSU 50% of 1-RM conditions for the external obliques and erector spinae across all lifts examined. Furthermore, there were no significant differences between the BOSU 50% of 1-RM and stable 50% of 1-RM conditions across all muscles and lifts examined.

Conclusions:

The current study did not demonstrate any advantage in utilizing the BOSU Balance Trainer. Therefore, fitness trainers should be advised that each of the aforementioned lifts can be performed while standing on stable ground without losing the potential core muscle training benefits.

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Sherry Robertson and Margo Mountjoy

.L. , Berglund , L. , & Berglund , B. ( 2008 ). Special attention to the weight-control strategies employed by Olympic athletes striving for leanness is required . Clinical Journal of Sport Medicine, 18 , 5 – 9 . PubMed ID: 18185032 doi:10.1097/JSM.0b013e31804c77bd 10.1097/JSM.0b013e31804c77bd Holick

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Franco M. Impellizzeri

, disinformation, and manipulation to the masses. Sport science and sport medicine are not alone in the ever-expanding use of social media—it is common in all scientific fields and, indeed, walks of life. Social communities focusing on fitness, sport training, and nutrition are also widespread, and it is now

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Martin C. Waller, Deborah A. Kerr, Martyn J. Binnie, Emily Eaton, Clare Wood, Terreen Stenvers, Daniel F. Gucciardi, Carmel Goodman and Kagan J. Ducker

.A. , Fung , T.S. , Doyle-Baker , P.K. , Verhoef , M.J. , & Reimer , R.A. ( 2007 ). Dietary supplementation of high-performance Canadian athletes by age and gender . Clinical Journal of Sport Medicine, 17 , 458 – 464 . doi:10.1097/JSM.0b013e31815aed33 10.1097/JSM.0b013e31815aed33 Erdman , K

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Hyun Chul Jung, Myong Won Seo, Sukho Lee, Sung Woo Jung and Jong Kook Song

: Academic Press . Constantini , N.W. , Arieli , R. , Chodick , G. , & Dubnov-Raz , G. ( 2010 ). High prevalence of vitamin D insufficiency in athletes and dancers . Clinical Journal of Sport Medicine, 20 , 368 – 371 . PubMed ID: 20818195 doi:10.1097/JSM.0b013e3181f207f2 10.1097/JSM.0b013e3181

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Sarah Staal, Anders Sjödin, Ida Fahrenholtz, Karen Bonnesen and Anna Katarina Melin

dysfunction in dancers . Clinical Journal of Sport Medicine, 21 , 119 – 125 . PubMed ID: 21358502 doi:10.1097/JSM.0b013e3182042a9a 10.1097/JSM.0b013e3182042a9a Kaufman , B.A. , Warren , M.P. , Dominguez , J.E. , Wang , J. , Heymsfield , S.B. , & Pierson , R.N. ( 2002 ). Bone density and