title: Validation of a personal fluid loss monitor.
abstract: Dehydration raises heat injury risk and reduces performance [ , , ]. The purpose was to validate the Hydra-Alert Jr (Acumen). The Hydra-Alert was tested in two exercise/clothing conditions. Participants wore it while wearing exercise clothing and exercising at a self-selected intensity (n = 8). Others wore the Hydra-Alert while wearing a ballistic-vest and performing an industrial-protocol (n = 8). For each condition, the Hydra-Alert was tested on two occasions (T1 and T2). The Hydra-Alert was tested against nude weight loss for both conditions. The Hydra-Alert had low test-retest reliability for both conditions (average absolute value of the error between Hydra-Alert outputs of T1 and T2 = 0.08 +/- 0.08 percentage points). With exercise-clothing, the Hydra-Alert evidenced low-moderate correlations between percent nude weight loss and Hydra-Alert output at 20 min (r = 0.59-T1, p = 0.13; r = 0.12-T2, p = 0.78), at 40 min (r = 0.93-T1, p = 0.001; r = 0.63-T2, p = 0.10), and at approximately 2 % weight loss (r = 0.21-T1 and T2, p = 0.61 and 0.62, respectively). The correlation at 40 min during T1 fell during T2 suggesting the Hydra-Alert was inconsistent. When wearing a ballistic-vest, the Hydra-Alert had poor validity (T1: r = - 0.29 [p = 0.48] for weight loss vs. monitor; T2: r = 0.11 [p = 0.80]). At the higher levels of dehydration ( approximately 2 %), the Hydra-Alert error was so high as to render its readings of little value. In some cases, the Hydra-Alert could lead to a false level of security if dehydrated. Therefore, the Hydra-Alert is of little use for those who want to measure their fluid loss while exercising in the heat.
authors.affiliation: Department of Health, Physical Education, and Sport Science, Kennesaw State University, Kennesaw, GA 30144-5591, USA. wickwire@kennesaw.edu
authors.forename: J
authors.initials: J
authors.lastname: Wickwire
authors.forename: P A
authors.initials: PA
authors.lastname: Bishop
authors.forename: J M
authors.initials: JM
authors.lastname: Green
authors.forename: M T
authors.initials: MT
authors.lastname: Richardson
authors.forename: R G
authors.initials: RG
authors.lastname: Lomax
authors.forename: C
authors.initials: C
authors.lastname: Casaru
authors.forename: E
authors.initials: E
authors.lastname: Jones
authors.forename: M
authors.initials: M
authors.lastname: Curtner-Smith
mesh_terms: D000328:Adult; D001834:Body Water / Q000378:metabolism; D003681:Dehydration / Q000378:metabolism*; D005080:Exercise Test / Q000379:methods; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D014481:United States; D014882:Water-Electrolyte Balance / Q000502:physiology