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Christie Powell, Jody Jensen and Samantha Johnson

Context : As sport participation increases globally, so will injury-related risks. The process used to determine return-to-sport following injury is vital to future sport participation and injury prevention. Early specialization along with poor management of sport participation causes an increase in injury risk and potential long-term health consequences for youth athletes. Objectives : Previous injury is a common intrinsic risk factor for new injuries. Identifying functional performance deficits, defined by return-to-sport criteria, minimizes these risk factors and provides athletes with guidelines to return safely to sport. The purposes of this clinical commentary and literature review are to provide a summary of current concepts and clinical practices and to identify functional performance measures as clinical assessment tools for return-to-play criteria in the youth population. Evidence : A literature review was completed using numerous databases, where 154 relevant articles were reviewed and 22 articles were included in this commentary. Of the 22 articles using functional performance measures for return-to-sport criteria, 6 were specific to youth, 12 had mixed populations of adults and youth, and 4 were normative samples for specific youth populations. Acquisition : The gaps in the literature pertaining to functional performance measures in the youth population are addressed, and future research needs for return-to-sport criteria are identified. Evidence Synthesis : This descriptive literature review identifies 22 articles that meet the search criteria for the youth population discussing the use of clinical functional performance measures in order to identify return-to-sport criteria for lower-extremity injuries. Conclusions: Due to the inconsistencies in terminology, definitions, and standardization of clinical assessment tools, it seems necessary to create a comprehensive functional performance test battery for the lower extremity that can be used as return-to-sport criteria.

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Eric Kyle O’Neal, Samantha Louise Johnson, Brett Alan Davis, Veronika Pribyslavska and Mary Caitlin Stevenson-Wilcoxson

The legitimacy of urine specific gravity (USG) as a stand-alone measure to detect hydration status has recently been challenged. As an alternative to hydration status, the purpose of this study was to determine the diagnostic capability of using the traditional USG marker of >1.020 to detect insufficient recovery fluid consumption with consideration for moderate versus high sweat losses (2.00–2.99 or >3% body mass, respectively). Adequate recovery fluid intake was operationally defined as ≥100% beverage fluid intake plus food water from one or two meals and a snack. Runners (n = 59) provided 132 samples from five previous investigations in which USG was assessed 10–14 hr after 60–90 min runs in temperate-to-hot environments. Samples were collected after a meal (n = 58) and after waking (n = 74). When sweat losses exceeded 3% body mass (n = 60), the relationship between fluid replacement percentage and USG increased from r = −.55 to −.70. Correct diagnostic decision improved from 66.6 to 83.3%, and receiver operating characteristic area under the curve increased the diagnostic accuracy score from 0.76 to approaching excellent (0.86). Artifacts of significant prerun hyperhydration (eight of 15 samples has USG <1.005) may explain false positive diagnoses, while almost all (84%) cases of false positives were found when sweat losses were <3.0% of body mass. Evidence from this study suggests that euhydrated runners experiencing significant sweat losses who fail to reach adequate recovery fluid intake levels can be identified by USG irrespective of acute meal and fluid intake ∼12-hr postrun.

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Mary Caitlin Stevenson Wilcoxson, Samantha Louise Johnson, Veronika Pribyslavska, James Mathew Green and Eric Kyle O’Neal

Runners are unlikely to consume fluid during training bouts increasing the importance of recovery rehydration efforts. This study assessed urine specific gravity (USG) responses following runs in the heat with different recovery fluid intake volumes. Thirteen male runners completed 3 evening running sessions resulting in approximately 2,200 ± 300 ml of sweat loss (3.1 ± 0.4% body mass) followed by a standardized dinner and breakfast. Beverage fluid intake (pre/postbreakfast) equaled 1,565/2,093 ml (low; L), 2,065/2,593 ml (moderate; M) and 2,565/3,356 mL (high; H). Voids were collected in separate containers. Increased urine output resulted in no differences (p > .05) in absolute mean fluid retention for waking or first postbreakfast voids. Night void averages excluding the first void postrun (1.025 ± 0.008; 1.013 ± 0.008; 1.006 ± 0.003), first morning (1.024 ± 0.004; 1.015 ± 0.005; 1.014 ± 0.005), and postbreakfast (1.022 ± 0.007; 1.014 ± 0.007; 1.008 ± 0.003) USG were higher (p < .05) for L versus M and H respectively and more clearly differentiated fluid intake volume between L and M than color or thirst sensation. Waking (r = -0.66) and postbreakfast (r = -0.71) USG were both significantly correlated (p < .001) with fluid replacement percentage, but not absolute fluid retention. Fluid intake M was reported as most similar to normal consumption (5.6 ± 1.0 on 0–10 scale) after breakfast and equaled 122 ± 16% of sweat losses. Retention data suggests consumption above this level is not warranted or actually practiced by most runners drinking ad libitum, but that periodic prerun USG assessment may be useful for coaches to detect runners that habitually consume low levels of fluids between training bouts in warm seasons.