Int J Sports Med 2008; 29(2): 139-144
DOI: 10.1055/s-2007-965319
Training & Testing

© Georg Thieme Verlag KG Stuttgart · New York

Validation of a Personal Fluid Loss Monitor

J. Wickwire1 , P. A. Bishop2 , J. M. Green2 , M. T. Richardson2 , R. G. Lomax3 , C. Casaru2 , E. Jones2 , M. Curtner-Smith2
  • 1Department of Health, Physical Education, and Sport Science, Kennesaw State University, Kennesaw, GA, USA
  • 2Department of Kinesiology, The University of Alabama, Tuscaloosa, AL, USA
  • 3College of Education, The Ohio State University, Columbus, OH, USA
Further Information

Publication History

accepted after revision November 29, 2006

Publication Date:
24 October 2007 (online)

Abstract

Dehydration raises heat injury risk and reduces performance [[2], [5], [6]]. 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 ∼ 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 (∼ 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.

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Ph.D. Jason Wickwire

Department of Health, Physical Education, and Sport Science
Kennesaw State University

1000 Chastain Rd

Kennesaw, GA 30144-5591

USA

Phone: + 1 77 04 99 34 25

Fax: + 1 77 04 23 65 61

Email: wickwire@kennesaw.edu

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