A Glucocorticoid Receptor Gene Polymorphism (BclI) Is Associated With Cardiorespiratory Fitness

Gene-environment interactions can influence health outcomes and genetic variation may impart resilience or vulnerability. Specialized military groups often seek methods to enhance their physical fitness even when it is categorized as superior. Individualized training that considers genetic predisposition to yield improvement is one such approach. We have previously demonstrated that genetics can significantly impact mental health, stress responses, and cardiorespiratory fitness (CRF). PURPOSE: In the present evaluation, we explored the effect of the BclI glucocorticoid receptor gene variant (rs41423247) on CRF. METHODS: Male, U.S. Navy Explosive Ordnance Disposal technicians (N = 111) participated in this cross-sectional study. They provided a saliva sample for genetic determination and completed a graded exercise test to determine maximum rate of oxygen consumption (VO2max). While controlling for age, univariate analyses of variance were used to evaluate the relationship between BclI genotypes and VO2max. RESULTS: In a three-genotype model (CC, CG, GG), BclI was associated with VO2max, F(2,107) = 4.932, p = .009, η2p = .084, 1-β = .798. To further decompose this result, we performed post hoc comparisons using dominant allele models. In the G-dominant model, homozygous C carriers had higher VO2max values compared with G carriers, F(1,108) = 9.806, p = .002, η2p = .083, 1-β = .874. There were no differences between GG and C carriers in the C-dominant model. CONCLUSIONS: Our results are aligned with the broader literature, which reports a connection between glucocorticoid receptor gene polymorphisms and cardiovascular health. These findings have implications for military training and may be used to inform personalized CRF regimens. Defense Health Agency, Military Operational Medicine Research Program