Sports Medicine

, Volume 43, Issue 12, pp 1289–1299 | Cite as

The Quantification of Body Fluid Allostasis During Exercise

  • Nicholas TamEmail author
  • Timothy D. Noakes
Review Article


The prescription of an optimal fluid intake during exercise has been a controversial subject in sports science for at least the past decade. Only recently have guidelines evolved from ‘blanket’ prescriptions to more individualised recommendations. Currently the American College of Sports Medicine advise that sufficient fluid should be ingested to ensure that body mass (BM) loss during exercise does not exceed >2 % of starting BM so that exercise-associated medical complications will be avoided. Historically, BM changes have been used as a surrogate for fluid loss during exercise. It would be helpful to accurately determine fluid shifts in the body in order to provide physiologically appropriate fluid intake advice. The measurement of total body water via D2O is the most accurate measure to detect changes in body fluid content; other methods, including bioelectrical impedance, are less accurate. Thus, the aim of this review is to convey the current understanding of body fluid allostasis during exercise when drinking according to the dictates of thirst (ad libitum). This review examines the basis for fluid intake prescription with the use of BM, the concepts of ‘voluntary and involuntary dehydration’ and the major routes by which the body gains and loses fluid during exercise.


Total Body Water Prolonged Exercise Body Mass Loss Body Mass Change Respiratory Water Loss 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The authors would like to thank Discovery Health, the University of Cape Town Staff Research Fund, the Medical Research Council of South Africa, Deutsche Akadimischer Austache Dienst and the National Research Foundation of South Africa for general funding.

Conflicts of interest

No sources of funding were used to assist in the preparation of this review. The authors have no conflicts of interest that are directly relevant to the content of this review.


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Copyright information

© Springer International Publishing Switzerland 2013

Authors and Affiliations

  1. 1.UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa

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