Maintaining proper hydration is a challenge for athletes. Dehydration can result in decreased athletic performance and potentially life-threatening complications. While the dangers of dehydration are well known, there is no literature investigating how training load and the environment affect hydration status during multiple bouts of soccer training. Therefore, Sekiguchi and colleagues investigated how training load and the environmental conditions relate to hydration status during a collegiate pre-season. Twenty-eight NCAA Division 1 male soccer players participated in this 19-day study. Prior to each training session, the body mass, urine specific gravity, and urine color of all participants were recorded and each participant consumed 500 mL of water. Participants wore a heart rate monitor and GPS-based tracker to track session-time, total distance, total distance per session, average heart rate, average speed, and training load score (individualized score accounting for a person’s activity and fitness). Researchers also considered the ambient temperature and relative humidity, which the nearest local weather station collected. During training, all participants had unlimited access to water, and water intake during this time was not recorded. Following any bout of training, participants consumed another 500 mL of water and body mass was assessed to determine change that occurred during training. The typical temperature during a session ranged from 20 to 28°C with relative humidity between 53 to 89%. The percent body mass loss never exceeded 2% during a session. On average, participants arrived at more than 80% of training sessions hypohydrated based on urine specific gravity, urine color, or both. The total distance during training was the most important factor associated with percent body mass loss. Relative humidity and ambient temperature only contributed a little bit to estimating the percent body mass loss.
