Factors influencing hydration status during a National Collegiate Athletics Association division 1 soccer preseason

Abstract

Objectives: To investigate the roles that training load and environmental conditions have on fluid balance during a collegiate men's soccer preseason.

Design: Observational study.

Methods: Twenty-eight male collegiate soccer players (mean±SD; age, 20±1.7y; body mass (BM), 79.9±7.3kg; height, 180.9±6.8cm; body fat, 12.7±3.1%; VO_2max, 50.7±4.3ml·kg^-1·min^-1) participated in this study. Prior to (PRE) and following (POST) each team session, BM, percent BM loss (%BML) and hydration status was measured. Participants donned a heart rate and GPS enabled monitor to measure training load. For all team activities, ambient temperature (T_AMB) and relative humidity (RH) were obtained from the nearest local weather station. Participants consumed 500mL of water as part of the team-based hydration strategy before and after training session. Stepwise linear regression was used to identify the variables that predicted %BML. Significance was set a-priori p<0.05.

Results: Total distance covered predicted %BML during all preseason activities (r²=0.253, p<0.001), with T_AMB and RH further adding to the model (r²=0.302, p<0.001). %BML never exceeded 2% of BM during any one session and daily variation in BM was <1% from baseline measures. Urine specific gravity was greater than 1.020 on 12/15days and U_COL was above 4 on 13/15days, indicating a state of hypohydration.

Conclusions: Total distance covered was the best predictor for the extent of body water losses during a collegiate preseason. While the team-based hydration strategy during preseason was successful in minimizing fluid losses during activity, participants arrived hypohydrated 80% of the time, necessitating a greater focus on daily fluid needs.

Keywords: Ambient temperature; Body mass loss; Dehydration; Fluid regulation; Training load.