title: Urinary creatine at rest and after repeated sprints in athletes: a pilot study.
abstract: Creatine plays a key role in muscle function and its evaluation is important in athletes. In this study, urinary creatine concentration was measured in order to highlight its possible significance in monitoring sprinters. The study included 51 sprinters and 25 age- and sex-matched untrained subjects as a control group. Body composition was measured and dietary intake estimated. Urine samples were collected before and after standardized physical exercise. Creatine was assessed by gas chromatography mass spectrometry. Basal urinary creatine (UC) was significantly lower in sprinters than controls (34±30 vs. 74±3 µmol/mmol creatinine, p < 0.05). UC was inversely correlated with body mass (r = -0.34, p < 0.01) and lean mass (r = -0.30, p < 0.05), and positively correlated with fat mass (r = 0.32, p < 0.05). After acute exercise, urinary creatine significantly decreased in both athletes and controls. UC is low in sprinters at rest and further decreases after exercise, most likely due to a high uptake and use of creatine by muscles, as muscle mass and physical activity are supposed to be greater in athletes than untrained subjects. Further studies are needed to test the value of urinary creatine as a non-invasive marker of physical condition and as a parameter for managing Cr supplementation in athletes.
authors.affiliation: Laboratory of Biochemistry, Rabta Hospital, Tunisia ; Research Laboratory "Sport Performance Optimization", National Center for Medicine and Sciences of Sports, Tunisia.
authors.forename: I
authors.initials: I
authors.lastname: Bezrati-Benayed
authors.affiliation: Laboratory of Biochemistry, Rabta Hospital, Tunisia.
authors.forename: F
authors.initials: F
authors.lastname: Nasrallah
authors.affiliation: Laboratory of Biochemistry, Rabta Hospital, Tunisia ; Department of Physiology, Faculty of Medicine of Tunis, Tunisia.
authors.forename: M
authors.initials: M
authors.lastname: Feki
authors.affiliation: Research Laboratory "Sport Performance Optimization", National Center for Medicine and Sciences of Sports, Tunisia ; Research and Education Centre, Aspetar, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: K
authors.initials: K
authors.lastname: Chamari
authors.affiliation: Laboratory of Biochemistry, Rabta Hospital, Tunisia ; Department of Physiology, Faculty of Medicine of Tunis, Tunisia.
authors.forename: S
authors.initials: S
authors.lastname: Omar
authors.affiliation: Department of Nutrition, National Institute of Nutrition, Tunisia.
authors.forename: L
authors.initials: L
authors.lastname: Alouane-Trabelsi
authors.affiliation: Department of Physiology, Faculty of Medicine of Tunis, Tunisia.
authors.forename: A
authors.initials: A
authors.lastname: Ben Mansour
authors.affiliation: Laboratory of Biochemistry, Rabta Hospital, Tunisia.
authors.forename: N
authors.initials: N
authors.lastname: Kaabachi
keywords: athlete; creatine; exercise; physical performance; sprinter