European Journal of Applied Physiology

, Volume 105, Issue 6, pp 959–967

Change in body mass accurately and reliably predicts change in body water after endurance exercise

  • Lindsay B. Baker
  • James A. Lang
  • W. Larry Kenney
Original Article

DOI: 10.1007/s00421-009-0982-0

Cite this article as:
Baker, L.B., Lang, J.A. & Larry Kenney, W. Eur J Appl Physiol (2009) 105: 959. doi:10.1007/s00421-009-0982-0
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Abstract

This study tested the hypothesis that the change in body mass (ΔBM) accurately reflects the change in total body water (ΔTBW) after prolonged exercise. Subjects (4 men, 4 women; 22–36 year; 66 ± 10 kg) completed 2 h of interval running (70% VO2max) in the heat (30°C), followed by a run to exhaustion (85% VO2max), and then sat for a 1 h recovery period. During exercise and recovery, subjects drank fluid or no fluid to maintain their BM, increase BM by 2%, or decrease BM by 2 or 4% in separate trials. Pre- and post-experiment TBW were determined using the deuterium oxide (D2O) dilution technique and corrected for D2O lost in urine, sweat, breath vapor, and nonaqueous hydrogen exchange. The average difference between ΔBM and ΔTBW was 0.07 ± 1.07 kg (paired t test, P = 0.29). The slope and intercept of the relation between ΔBM and ΔTBW were not significantly different from 1 and 0, respectively. The intraclass correlation coefficient between ΔBM and ΔTBW was 0.76, which is indicative of excellent reliability between methods. Measuring pre- to post-exercise ΔBM is an accurate and reliable method to assess the ΔTBW.

Keywords

Hydration statusProlonged exerciseFluid replacementDeuterium oxideFourier transform infrared spectroscopy

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Lindsay B. Baker
    • 1
    • 2
  • James A. Lang
    • 1
  • W. Larry Kenney
    • 1
  1. 1.Noll Laboratory, Kinesiology DepartmentPennsylvania State UniversityUniversity ParkUSA
  2. 2.Gatorade Sports Science InstituteBarringtonUSA