Dehydration, Wellness, and Training Demands of Professional Soccer Players during Preseason.

Purpose: Our study is aimed at analyzing the relationships between water loss and a professional soccer team's internal and external training load throughout the first three months of a season, covering all the preseason and the first two months of the competitive season.

Methods: This study followed an observational analytic design. Twenty-seven athletes (age: 25.5 ± 4.1 years, height: 180.7 ± 8.2 cm, and body mass: 78.4 ± 8.7 kg) were included in the study, conducted over the first three months of the season. Players were weighed at the beginning and end of all training sessions to estimate fluid losses. They were asked to complete a wellness questionnaire and indicate the color of the first urine of the day upon their arrival at the practice session. Additionally, all sessions were monitored for locomotor demands.

Results: We found a positive correlation between urine color and sprint distance ( = 0.46, = 0.01) and a positive correlation between dehydration and rating of perceived exertion ( = 0.44, = 0.015), whereas a negative correlation between dehydration and number of acceleration ( = -0.39, = 0.034).

Conclusions: Dehydration increased perceived physical exertion. Regularly monitoring training load and changes in body mass, as well as raising awareness about hydration, can contribute to cognitive and physical performance.