Association between body fat response to exercise training and multilocus ADR genotypes

Objective: To examine the contribution of adrenergic receptor (ADR) gene polymorphisms and their gene-gene interactions to the variability of exercise training-induced body fat response. Research Methods and Procedures: This was an intervention study that used a volunteer sample of 70 healthy, sedentary men (n = 29) and postmenopausal women (n = 41) 50 to 75 years of age, with a BMI less than or equal to37 kg/m(2), from the Washington, DC, metropolitan area. Participants completed 6 weeks of dietary stabilization (American Heart Association diet) before 24 weeks of supervised aerobic exercise training. Diet was maintained throughout the intervention. Change in percent total body fat, percent trunk fat, and fat mass by DXA in ADR genotype groups (Glu(12)/Glu(9) alpha2b-ADR, Trp64Arg beta3-ADR, and Gln27Glu beta2-ADR) at base-line and after 24 weeks of aerobic exercise training was measured. Results: In multivariate analysis (covariates: age, gender, and baseline value of phenotype), best fit models for percent total body and trunk fat response to exercise training retained main effects of all three ADR gene loci and the effects of each gene-gene interaction (p = 0.009 and 0.003, respectively). Similarly, there was a trend for the fat mass response model (p = 0.03). The combined genetic factors explained 17.5% of the overall model variability for percent total body fat, 22% for percent trunk fat, and 10% for fat mass. Discussion: The body fat response to exercise training in older adults is associated with the combined effects of the Glu(12)/Glu(9) alpha2b-, Trp64Arg beta3-, and Gln27Glu beta2-ADR gene variants and their gene-gene interactions.