Abstract
Creatine monohydrate is one of the most widely used ergogenic supplements; however, acute and short-term changes in urinary markers following supplementation are not fully characterized in healthy adults. PURPOSE: To examine acute (3 h, 6 h) and short-term (8 d) changes in urinary creatinine measures following creatine supplementation in healthy males and females. METHODS: Eighteen recreationally active young adults (8 females; 21.4 ± 3.1 years, 171.2 ± 10.0 cm, 72.6 ± 13.6 kg, and 24.6 ± 4.8 kg/m2) completed the study thus far. Participants ingested creatine monohydrate supplementation at a dose of 5 g·day⁻¹ for 7 consecutive days. Measures were taken at baseline, 3h-, 6h-, and 8d-post-creatine ingestion. Participants provided a urine sample and underwent bioimpedance spectroscopy technology (BIS) assessments of total body water (TBW), intracellular fluid (ICF), and extracellular fluid (ECF) at each time point. Urine specific gravity (USG) was also measured and recorded for each session. Urinary creatinine and USG concentrations, TBW, ICF, and ECF were analyzed across time points using a 4 × 2 mixed-design ANOVA (sex × time). RESULTS: The time × sex interaction (p = .180, η2 = .180), the main time effect (p = .404, η2 = .209), and the main effect for sex (p = .089, η2 = .556) were not significant in urinary creatinine. There was a significant main effect of time for the USG readings (p = .005, η2 = .249), with 8d-post creatine ingestion having larger USG values (1.014 ± .01) than 3h-post ingestion (1.006 ± .008, p = .015). However, there were no significant interaction (p = .394) or sex differences (p = .721). When analyzing TBW, there were no significant main effects for time (p = .385) or interaction (p = .404), but there were significant sex differences (p = .002, η2 = .477). There were no significant main effects for ECF time (p = .203, η2 = .091), interaction (p = .207, η2 = .091), or sex (p = .418, η2 = .090). No main effects of time (p = .283, η2 = .076), interaction (p = .283, η2 = .085), or sex (p = .231, η2 = .088) were found in ICF. CONCLUSION: Short-term creatine supplementation (5 g·day⁻¹ for 7 days) did not significantly affect urinary creatinine or body fluid compartments in healthy males and females. There were increases in USG on day 8, but participants were in the state of euhydration at all time points. Overall, our preliminary analysis of creatine supplementation produced minimal acute or short-term changes in urinary creatinine and body fluid measures. The only sex differences found occurred in TBW, with males having larger TBW (%) than females.
Recommended Citation
Lambright, Kelsi R.; Clark, Cayla; Gaibor Verdezoto, Tatiana C.; Davila, Edwin J.; Willoughby, Darryn; and Newmire, Dan E.
(2026)
"Acute and Short-Term Effects of Creatine Supplementation on Urinary Creatinine and Body Water in Young Healthy Adults: A Preliminary Analysis,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
18, Article 228.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss18/228