Hydration behaviors before and after an educational and prescribed hydration intervention in adolescent athletes.

CONTEXT

The effectiveness of education in modifying hydration behaviors in adolescent athletes is unclear.

OBJECTIVE

To assess the hydration status and behaviors of female athletes before and after a 1-time educational intervention and prescribed hydration intervention in a warm, humid, tropical environment.

DESIGN

Cohort study.

SETTING

Non-air-conditioned gymnasium in a tropical environment (indoor wet bulb globe temperature = 24.0 ± 0.2°C). Patient or Other Participants: Thirty-six female adolescent elite volleyball players (age = 14.8 ± 0.8 years, height = 168.2 ± 8.2 cm, mass = 60.8 ± 9.0 kg, body mass index = 21.7 ± 2.7, body surface area = 1.65 ± 0.14 m(2), body surface area to mass ratio = 2.71 ± 0.18 m(2)·kg(-1)·10(-2)) participated.

INTERVENTION(S): Four observational periods consisting of 3 practices per observational period separated by 48 hours. The 4 periods included a control period, educational intervention, prescribed hydration intervention (PHI), and observational follow-up (OF-U). After the control period, an educational intervention consisting of a slide presentation was provided to the participants, followed by a week of observation. In the PHI, a precalculated volume of water based on individual sweat rate was consumed every 20 minutes during each 2-hour practice. During all other periods, participants consumed their fluid of choice ad libitum. The order of the treatment periods was not randomized and was the same for all participants.

MAIN OUTCOME MEASURE(S): Prepractice to postpractice changes in body mass (ΔBM), percentage of body mass lost (%BML), urine specific gravity, urine color, urine osmolality, sweat rate, and volume of fluid consumed (F(vol)).

RESULTS

The PHI was the only period during which participants maintained body mass (ΔBM = 0.05 ± 1.3%); F(vol) consumed was greatest during this time (F(vol) = 1.3 ± 0.4 L; F(1,3) = 34.869, P ≤ .001). TheΔBM was less for the PHI (ΔBM = 0.05 ± 0.9 kg, %BML = 0.04 ± 1.3%) than the OF-U period (ΔBM = -0.7 ± 1.1 kg, %BML = -1.2 ± 1.9%; F(1,3) = 6.220, P = .01). The F(vol) (1.3 ± 0.4 L) and percentage of fluid consumed (143.7 ± 110.8%) to restore sweat loss for the PHI period were higher than for any other period (F(1,3) = 34.869, P ≤ .001). None of the participants experienced serious dehydration in any of the conditions.

CONCLUSIONS

A 1-time education session alone was not successful in changing hydration behaviors. However, prescribing individualized hydration protocols improved hydration for adolescents exercising in a warm, humid environment.