Sex differences in hydration biomarkers and test-retest reliability following passive dehydration

Document Type

Journal Article

Publication Title

International Journal of Sport Nutrition and Exercise Metabolism

Volume

34

Issue

2

First Page

88

Last Page

100

PubMed ID

38215737

Publisher

Human Kinetics

School

School of Medical and Health Sciences

Comments

Doherty, C. S., Fortington, L. V., & Barley, O. R. (2024). Sex differences in hydration biomarkers and test-retest reliability following passive dehydration. International Journal of Sport Nutrition and Exercise Metabolism, 32(2), 88-100. https://doi.org/10.1123/ijsnem.2023-0146

Abstract

This study investigated (a) differences between males and females for changes in serum, tear, and urine osmolality, hematocrit, and urine specific gravity following acute passive dehydration and (b) assessed the reliability of these biomarkers separately for each sex. Fifteen males (age: 26.3 ± 3.5 years, body mass: 76 ± 7 kg) and 15 females (age: 28.8 ± 6.4 years, body mass: 63 ± 7 kg) completed a sauna protocol twice (5-28 days apart), aiming for 4% body mass loss (BML). Urine, blood, and tear markers were collected pre- and postdehydration, and change scores were calculated. Male BML was significantly greater than that of females in Trial 1 (3.53% ± 0.55% vs. 2.53% ± 0.43%, p < .001) and Trial 2 (3.36% ± 0.66% vs. 2.53% ± 0.44%, p = .01). Despite significant differences in BML, change in hematocrit was the only changemarker that displayed a significant difference in Trial 1 (males: 3% ± 1%, females: 2% ± 1%, p = .004) and Trial 2 (males: 3% ± 1%, females: 1% ± 1%, p = .008). Regression analysis showed a significant effect for sex (male) predicting change in hematocrit (B = 0.8, p = .032) and change in serum osmolality (B = -3.3, p = .005) when controlling for BML but not for urinary or tear measures. The intraclass correlation coefficients for females (ICC 2, 1) were highest for change in urine specific gravity (ICC = .62, p = .006) and lowest for change in tear osmolarity (ICC = -.14, p = .689), whereas for males, it was posthematocrit (ICC = .65, p = .003) and post tear osmolarity (ICC = .18, p = .256). Generally, biomarkers showed lower test-retest reliability in males compared with females but, overall, were classified as poor-moderate in both sexes. These findings suggest that the response and reliability of hydration biomarkers are sex specific and highlight the importance of accounting for BML differences.

DOI

10.1123/ijsnem.2023-0146

Access Rights

subscription content

Share

 
COinS