Elite Kenyan endurance runners are hydrated day-to-day with ad libitum fluid intake

Previous studies of elite Kenyan endurance runners reported that athletes did not consume liquids before or during training and infrequently consumed modest amounts of liquids after training that contributed to low daily fluid intake. Purpose: To assess hydration status of elite Kenyan endurance runners during an important training period. Methods: Hydration status was monitored in fourteen elite Kenyan endurance runners over a 5-d training period 1 wk prior to the Kenyan national trials for the 2005 IAAF Athletics World Championships by measuring body mass, urine osmolality, total body water, and daily fluid intake. Dietary sodium (Na) intake was estimated using a 5-d nutritional diary and biochemical analysis, whilst [Na] was determined in urine and sweat. Intestinal temperature was monitored continuously during training sessions. Results: Daily fluid intake was consistent with previous observations. There was a significant body mass loss during the morning, interval, and afternoon training sessions (P < 0.05). Nevertheless, mean total body water and pretraining body mass were well maintained day-to-day throughout the 5-d recording period (P = 0.194 and P = 0.302, respectively). Furthermore, there was no significant difference between the osmolality of the morning urine sample and the evening sample (P = 0.685). Mean Na intake was not significantly different to Na loss in sweat and urine (P = 0.975). No athlete showed signs or symptoms of heat strain at any time. Conclusions: These results demonstrate that elite Kenyan endurance runners remain well hydrated day-to-day with an ad libitum fluid intake; a pattern and volume of fluid intake that is consistent with previous observations of elite Kenyan endurance runners.