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Increase of total body water with decrease of body mass while running 100 km nonstop--formation of edema?


Knechtle, B; Wirth, A; Knechtle, P; Rosemann, T (2009). Increase of total body water with decrease of body mass while running 100 km nonstop--formation of edema? Research Quarterly for Exercise and Sport, 80(3):593-603.

Abstract

We investigated whether ultraendurance runners in a 100-km run suffer a decrease of body mass and whether this loss consists of fat mass, skeletal muscle mass, or total body water. Male ultrarunners were measured pre- and postrace to determine body mass, fat mass, and skeletal muscle mass by using the anthropometric method. In addition, bioelectrical impedance analysis was used to determine total body water, and urinary (urinary specific gravity) and hematological parameters (hematocrit and plasma sodium) were measured in order to determine hydration status. Body mass decreased by 1.6 kg (p < .01), fat mass by 0.4 kg (p < .01), and skeletal muscle mass by 0.7 kg (p < .01), whereas total body water increased by 0.8 L (p < .05). Hematocrit and plasma sodium decreased significantly (p < .01), whereas plasma urea and urinary specific gravity (USG) increased significantly (p < .01). The decrease of 2.2% body mass and a USG of 1.020 refer to a minimal dehydration. Our athletes seem to have been relatively overhydrated (increase in total body water and plasma sodium) and dehydrated (decrease in body mass and increase in USG) during the race, as evidenced by the increased total body water and the fact that plasma sodium and hematocrit were lower postrace than prerace. The change of body mass was associated with the change of total body water (p < .05), and we presume the development of.

Abstract

We investigated whether ultraendurance runners in a 100-km run suffer a decrease of body mass and whether this loss consists of fat mass, skeletal muscle mass, or total body water. Male ultrarunners were measured pre- and postrace to determine body mass, fat mass, and skeletal muscle mass by using the anthropometric method. In addition, bioelectrical impedance analysis was used to determine total body water, and urinary (urinary specific gravity) and hematological parameters (hematocrit and plasma sodium) were measured in order to determine hydration status. Body mass decreased by 1.6 kg (p < .01), fat mass by 0.4 kg (p < .01), and skeletal muscle mass by 0.7 kg (p < .01), whereas total body water increased by 0.8 L (p < .05). Hematocrit and plasma sodium decreased significantly (p < .01), whereas plasma urea and urinary specific gravity (USG) increased significantly (p < .01). The decrease of 2.2% body mass and a USG of 1.020 refer to a minimal dehydration. Our athletes seem to have been relatively overhydrated (increase in total body water and plasma sodium) and dehydrated (decrease in body mass and increase in USG) during the race, as evidenced by the increased total body water and the fact that plasma sodium and hematocrit were lower postrace than prerace. The change of body mass was associated with the change of total body water (p < .05), and we presume the development of.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Institute of General Practice
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2009
Deposited On:19 Mar 2010 13:26
Last Modified:21 Nov 2017 14:45
Publisher:American Alliance for Health, Physical Education, Recreation and Dance
ISSN:0270-1367
Free access at:Official URL. An embargo period may apply.
Official URL:http://www.aahperd.org/rc/publications/rqes/upload/Sept-09-RQES-for-Web.pdf
Related URLs:http://www.aahperd.org/rc/publications/rqes/Indexes.cfm (Publisher)
PubMed ID:19791646

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