Serum creatine is not a reliable marker of muscular fitness in young adults

Abstract

© 2018 Informa UK Limited, trading as Taylor & Francis Group. Purpose: Elevated serum creatine and higher handgrip strength are individually associated with better health profiles yet the link between two variables remains unknown. In this cross-sectional study, we evaluated serum creatine levels in relation to handgrip strength in a cohort of 130 young healthy adults (61 women and 69 men; age 23.3 ± 2.6 years), while controlling for age, gender, fat-free mass and biomarkers of creatine metabolism as effect modifiers. Materials and methods: Serum creatine, creatinine and guanidinoacetic acid (GAA) levels were measured with liquid chromatography-tandem mass spectroscopy, while handgrip strength was assessed with a hydraulic hand dynamometer. Results: Hierarchical multiple regression revealed that our model as a whole explained 79.9% of the variance in handgrip strength (p < 0.001). However, the evaluation of the contribution of each independent variable revealed that gender and free-fat mass make significant contributions (45.4 and 31.8%, respectively) to our model (p < 0.05), while neither age (0.9%) nor serum creatine (4.5%) or any other lab markers made significant contributions to the model (p > 0.05). Conclusions: Having higher blood creatine appears to be unrelated with better physical performance in young healthy adults. Serum creatine was not a reliable marker of muscular fitness in this population.