INFLUENCE OF HYDRATION STATUS ON RUNNING PERFORMANCE IN HIGH SCHOOL CROSS COUNTRY RUNNERS

Abstract

Adequate hydration is crucial for athlete's health and performance. Although the impact of hypohydration on professional athletes have been well characterized, there is a dearth of information on the effect of hypohydration on younger populations, such as high school athletes, specifically cross-country runners in a hot and humid environment. PURPOSE: To characterize the effects of hydration status on running performance in high school cross-country runners and determine if a simple hydration plan can improve hydration status. METHODS: 15 high school cross-country runners (9 males, 6 females: 15.5 ± 1.2 yrs) participated in this study. The study took place over a two-week period with baseline testing (V1, V3) and a 5km running performance trials (V2, V4) occurring after school during normal practice hours, with V1 (V3) and V2 (V4) separated by 3 days. A simple hydration strategy of 32oz. of water in the morning and evening preceding the 5km performance trial was implemented to enhance the hydration status of the athletes. Changes in performance between V2 and V4 were determined by 5km completion time, and hydration status was determined by pre- and post-run urine specific gravity using a spectral refractometer. Changes in core temperatures in response to 5km runs were measured on V2 and V4 using core temperature pills. RESULTS: Participants were significantly hypohydrated at rest (USG; V1 = 1.031 ± 0.008, V2 = 1.033 ± 0.006, V3 = 1.030 ± 0.007), but the simple hydration strategy implemented after V3 significantly improved hydration in V4 (resting USG = 1.024 ± 0.008; p<0.001). The average 5km performance times were not significantly different between V2 and V4 (V2:1613.3±224.4 sec, V4:1716.2±176.1 sec), however changes in resting hydration status between V2 and V4 were significantly correlated with improvements in 5km performance time (p=0.02, Pearson’s r=0.63). Changes in core temperature from pre- to post-practice was significantly lower in V2 than V4 (V2:+0.79±0.7 0C, V4:+0.86±1.35 0C; p=0.04). CONCLUSION: High school cross-country runners are hypohydrated, and a simple hydration plan can improve hydration status. Improved hydration was correlated to lower performance times in our cohort of young athletes. The findings support that high school athlete’s hydration status is of concern and should be monitored.