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Exercise Science | Human and Clinical Nutrition | Kinesiology | Life Sciences | Nutrition | Sports Sciences


Amy Olson, Nutrition


Abstract: Dehydration exceeding 2% loss of body mass can cause decreased cognitive and physical performance in endurance athletes. While many runners carry water bottles with them, most do not know their sweat rate or fluid recommendations, increasing the risk for heat-related illnesses such as heat stroke. Purpose: To assess hydration status, habits, and knowledge of collegiate cross country runners. Methods: Institutional Review Board approval was obtained and subjects completed informed consents. Thirty-three female and twenty-five male Division III collegiate runners participated in the study. Hydration status was assessed measuring the specific gravity of three urine samples one each before a race, recovery run, and workout run. Participants completed questionnaires regarding hydration knowledge and habits. Sweat rates were calculated for each runner to estimate fluid losses. Water bottles were swabbed with a 3M quick swab around the lid and areas that touch the mouth and cultured using 3M aerobic petrifilms to assess cleanliness. ANOVA and T-tests were used for statistical analysis using SPSS. Results: There were no significant differences in the average urine specific gravity, however there was a bi-modal distribution and 50% of runners began the race dehydrated compared to 32.8% before the workout and 36.2% before the recovery run. Fluid consumption was significantly lower before the race compared to the other types of runs (Race: 443.4. ± 375mL, Workout: 1206.3 ± 552.6mL, Recovery: 1287 ± 792mL; p=0.002). Fluid consumption was similar between males and females before the workout and recovery run (Workout: males 1153.8 ± 459mL, females: 1235.4 ± 600.9mL, p=0.578; Recovery: males 1240.5 ± 664.8mL, females: 1209.6 ± 663.9mL, p=0.499). However, males did consume more fluid before the race (Males: 661.68 ± 471.6mL, Females: 324.6 ± 244.8mL; p=0.09) Sweat rates were higher in males (Males: 1377.6 ± 335.1mL/hr, Females: 1128.6 ± 320.7mL/h; p=0.005) and males ran more miles per week (males: 65.77 ± 12.6, females: 47.64 ± 10.17; p=.000). The average knowledge score was 58% for males and 61% for females. The majority (64.9%) of water bottles cultured had bacteria too numerous to count. Conclusions: Twenty-one percent of all participants (8 males, 4 females) were severely dehydrated prior to competition. Sweat rates (mL/hr) of males were 18% higher, and males ran on average 18 more miles per week, yet consumed approximately the same amount of fluid as females before the recovery and workout runs. Males consumed more fluid before the race, but 57% of males were dehydrated compared to 45% of females. Water bottle cleanliness should be addressed by runners. Total aerobic plate count only assesses the amount of bacteria and future research is needed to determine whether the bacteria is pathogenic.