Ad libitum fluid consumption via self-or external administration

Abstract

Context: During team athletic events, athletic trainers commonly provide fluids with water bottles. When a limited number of water bottles exist, various techniques are used to deliver fluids. Objective: To determine whether fluid delivered via water-bottle administration influenced fluid consumption and hydration status. Design: Crossover study. Setting: Outdoor field (22.2°C ± 3.5°C). Patients or Other Participants: Nineteen participants (14 men, 5 women, age = 30 ± 10 years, height = 176 ± 8 cm, mass = 72.5 ± 10 kg) were recruited from the university and local running clubs. Intervention(s): The independent variable was fluid delivery with 3 levels: self-administration with mouth-to-bottle direct contact (SA-DC), self-administration with no contact between mouth and bottle (SA-NC), and external administration with no contact between the mouth and the bottle (EA-NC). Participants warmed up for 10 minutes before completing 5 exercise stations, after which an ad libitum fluid break was given, for a total of 6 breaks. Main Outcome Measure(s): We measured the fluid variables of total volume consumed, total number of squirts, and average volume per squirt. Hydration status via urine osmolality and body-mass loss, and perceptual variables for thirst and fullness were recorded. We calculated repeated-measures analyses of variance to assess hydration status, fluid variables, and perceptual measures to analyze conditions across time. Results: The total volume consumed for EA-NC was lower than for SA-DC (P =.001) and SA-NC (P =.001). The total number of squirts for SA-DC was lower than for SA-NC (P =.009). The average volume per squirt for EA-NC was lower than for SA-DC (P=.020) and SA-NC (P=.009). Participants arrived (601.0 ± 21.3 mOsm/L) and remained (622.3 ± 38.3 mOsm/L) hydrated, with no difference between conditions (P =.544); however, the EA-NC condition lost more body mass than did the SA-DC condition (P =.001). There was no main effect for condition on thirst (P =.147) or fullness (P =.475). Conclusions: External administration of fluid decreased total volume consumed via a decreased average volume per squirt. The SA-DC method requires fewer squirts within a specific time frame. Fluid breaks every 15 minutes resulted in maintenance of euhydration; however, loss of body mass was influenced by fluid administration. Athletic trainers should avoid external administration to promote positive hydration behaviors. When fluid is self-administered, individual bottles may be the best clinical practice because more volume can be consumed per squirt.