An increased fluid intake leads to feet swelling in 100-km ultra-marathoners - an observational field study

• Main Authors: Cejka Caroline, Knechtle Beat, Knechtle Patrizia, Rüst Christoph, Rosemann Thomas
• Format: Article
• Language: English
• Published: BMC 2012-04-01
• Series: Journal of the International Society of Sports Nutrition
• Subjects: Fluid intake; Peripheral oedemas; Sodium; Hydrations status; Ultra-marathon
• Online Access: http://www.jissn.com/content/9/1/11
• ISSN: 1550-2783

<p>Abstract</p> <p>Background</p> <p>An association between fluid intake and changes in volumes of the upper and lower limb has been described in 100-km ultra-marathoners. The purpose of the present study was (<it>i</it>) to investigate the association between fluid intake and a potential development of peripheral oedemas leading to an increase of the feet volume in 100-km ultra-marathoners and (<it>ii</it>) to evaluate a possible association between the changes in plasma sodium concentration ([Na⁺]) and changes in feet volume.</p> <p>Methods</p> <p>In seventy-six 100-km ultra-marathoners, body mass, plasma [Na⁺], haematocrit and urine specific gravity were determined pre- and post-race. Fluid intake and the changes of volume of the feet were measured where the changes of volume of the feet were estimated using plethysmography.</p> <p>Results</p> <p>Body mass decreased by 1.8 kg (2.4%) (<it>p </it>< 0.0001); plasma [Na⁺] increased by 1.2% (<it>p </it>< 0.0001). Haematocrit decreased (<it>p </it>= 0.0005). The volume of the feet remained unchanged (<it>p </it>> 0.05). Plasma volume and urine specific gravity increased (<it>p </it>< 0.0001). Fluid intake was positively related to the change in the volume of the feet (<it>r </it>= 0.54, <it>p </it>< 0.0001) and negatively to post-race plasma [Na⁺] (<it>r </it>= -0.28, <it>p </it>= 0.0142). Running speed was negatively related to both fluid intake (<it>r </it>= -0.33, <it>p </it>= 0.0036) and the change in feet volume (<it>r </it>= -0.23, <it>p </it>= 0.0236). The change in the volume of the feet was negatively related to the change in plasma [Na⁺] (<it>r </it>= -0.26, <it>p </it>= 0.0227). The change in body mass was negatively related to both post-race plasma [Na⁺] (<it>r </it>= -0.28, <it>p </it>= 0.0129) and running speed (<it>r </it>= -0.34, <it>p </it>= 0.0028).</p> <p>Conclusions</p> <p>An increase in feet volume after a 100-km ultra-marathon was due to an increased fluid intake.</p>