Physical fitness influences water turnover and body water changes during trekking

• Published in: Medicine and science in sports and exercise 1998-05, Vol.30 (5), p.704-708
• Main Authors: FUSCH, C, GFRÖRER, W, DICKHUTH, H.-H, MOELLER, H
• Format: Article
• Language: English
• Subjects: Adult; Altitude; Biological and medical sciences; Body Composition; Female; Fundamental and applied biological sciences. Psychology; Humans; Lactic Acid - blood; Lactic Acid - metabolism; Male; Physical Endurance - physiology; Physical Fitness - physiology; Space life sciences; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Walking - physiology; Water-Electrolyte Balance
• ISSN: 0195-9131; 1530-0315
• DOI: 10.1097/00005768-199805000-00010

This study was performed to assess water turnover and changes of body water during a trekking tour at moderate altitude. Fifteen healthy normally trained adults participated in a 7-d backpack trek tour in the Swiss Alps (total walking distance: 120.5 km; cumulated altitude difference: 6990 m (uphill) and 7550 m downhill; lowest point: 1285 m; highest point: 3317 m). Total body water and water turnover were measured using deuterium dilution and elimination (oral load of 0.33 g 99.8% D2O per kg body weight, overnight equilibration period, pre- and postdose saliva samples immediately before and after sleep, analysis of D2O concentrations in saliva using Fourier-transform infrared spectroscopy, CV < 1%). Physical training state was assessed after the tour using the lactate-exercise intensity relationship obtained by performing 50-W increments every 3 min on a cycle ergometer. Body water decreased from the evening of day 0 to the evening of day 4 (from 45.3 +/- 7.3 L to 43.4 +/- 7.6 L, P < 0.05), and did not significantly decrease (43.5 +/- 7.9 L) until the evening of day 5 (maximum of trekking exercise intensity). Mean daily water turnover was 5.7 +/- 1.8 L x d(-1) corresponding to 78.7 +/- 17.5 mL x kg(-1) x d(-1). Body water changes and water turnover were significantly related to the exercise intensity obtained at the lactate threshold as well as at the level of 4 mM lactate. This correlation may be in part explained by differing glycogen content of muscle tissue.