Water intake, hydration status and related hydration biomarkers among physically active male young adults in Beijing, China: a cross-sectional study

Abstract

Studies on the water intake of athletes in daily life are insufficient. The objective was to determine the water intake and hydration status among physically active male young adults. In this cross-sectional studies study, 111 physically active male young adults were recruited. The amount of daily total drinking fluid intake (TDF) among participants was recorded and evaluated in real time over 7 days using the “7-day 24-hour fluid intake questionnaire” (liq. In7). The daily water intake from food (WFF) was calculated using the weighing, duplicate portion and direct-drying method over 3 days. All urine samples over 3 days were collected, and urine biomarkers were determined. According to 24-h urine osmolality, the participants were divided into three groups with Euhydrated status, middle hydration and hypohydration statuses. Finally, 109 participants completed the study. The median daily total water intake (TWI), TDF and WFF were 2701, 1789 and 955 mL, respectively. Among participants, 17 participants (16%) were in Euhydrated status, 47 participants (43%) were in hypohydration, and 45 participants (41%) were in middle hydration. There were statistical significances in the 24-h urine volume, osmolality, urine specific gravity, and concentrations of K, Na and Cl in different hydration statuses (χ2 = 28.212, P < 0.01; χ2 = 91.341, P < 0.01; χ2 = 47.721, P < 0.01; χ2 = 41.548, P < 0.01; χ2 = 46.863, P < 0.01; χ2 = 40.839, P < 0.01). Moderate-intensity correlations were found between the TDF and 24-h urine volume, 24-h urine osmolality, 24-h urine Na concentration, morning urine osmolality, and morning urine Na concentration (r = 0.408, P < 0.01; r=-0.378, P < 0.01; r=-0.325, P < 0.01; r=-0.344, P < 0.01; r=-0.329, P < 0.01). There were also moderate intensity correlations between the TDF and 24-h urine osmolality, morning urine osmolality, and morning urine Na concentration (r=-0.365, P < 0.01; r=-0.371, P < 0.01; r=-0.322, P = 0.01). Increased and higher moderate-intensity correlations were found between plain water and 24-h urine volume, 24-h urine osmolality, 24-h urine K and Na concentration, morning urine osmolality, and morning urine Na concentration (r = 0.374, P < 0.01; r=-0.520, P < 0.01; r=-0.312, P < 0.01; r=-0.355, P < 0.01; r=-0.446, P < 0.01; r=-0.378, P < 0.01). Insufficient water intake and hypohydration were common among physically active male young adults. The amount and type of water intake was correlated with hydration status and urine biomarkers.

Behaviors of Water Intake, Hydration Status, and Related Hydration Biomarkers among Physically Active Male Young Adults in Beijing, China: A Cross-Sectional Study

“…The study found that the hydration status of the participants may be closely related to their water intake, urination behavior, and urine indicators. Similar results were found in the research on young people in China [ 35 , 51 ]. The result of one study abroad found strong associations (| r | ≧ 0.6) between TDF and 24 h urine volume, osmolality, and USF among adults [ 3 ].…”

“…In this study, judging by 24 h urine osmolality, only 16% of the participants were in the hydration status and 43% were in hypohydration status. Compared with the results of the previous study conducted among young adults in China, the proportion of athletes with hydration status was lower and the proportion with hypohydration status was higher [ 51 ]. There are no further studies on the water intake and hydration status of athletes in daily life in China.…”

“…In this study, the median 24-hour urine volume of the participants was 850 mL, which was lower than the corresponding result in a previous study conducted among young adults in China (1272 mL) [ 35 , 51 ]. This may be because participants in this study were athletes with high-intensity physical activity and more water was lost through sweat.…”

“…In this study, the median TDF of the participants was 1789 ml, the median TWI was 2701 mL, and the proportion of TDF to TWI was 65.0%, which was higher than the corresponding results in the previous study, conducted with young adults in China (1214 mL, 2483 mL, and 48.9%) [ 35 , 51 ]. In this study, 56.0% of the participants reached the recommendations for adequate TDF for Chinese male adults (1700 mL), and 37.6% reached the recommendations for adequate TWI for Chinese male adults (3000 mL) [ 1 ], which was also higher than the corresponding results in the previous study conducted with young adults in China (23.5% and 25.0%) [ 35 , 51 ]. The percentages of participants whose TWI met the TWI recommendation for male adults set by the World Health Organization (WHO) and European Food Safety Authority (EFSA) were 42.2% and 68.8%, respectively.…”

“…The results of the study could provide scientific and accurate references for the development of recommendations on water intake for athletes. Moreover, for athletes and the general population, the data of the study could provide more clues and references for the establishment of comprehensive evaluation indexes on hydration status [ 41 ].…”