A genetic variant in IL‐15Rα correlates with physical activity among European–American adults

BACKGROUND: Interleukin‐15 (IL‐15) is a myokine associated with muscle strength, possibly by attenuating protein breakdown. A variant in the alpha‐receptor (IL‐15Rα 1775 A>C, rs2228059) partially modulates the muscle strength and size response to resistance training. We examined if this polymorphism associated with habitual physical activity among European‐American adults. METHODS: Men (n = 240, 23.7 ± 0.3 year, body mass index [BMI] 25.3 ± 0.3 kg/m(2)) and women (n = 292, 23.2 ± 0.3 year, 24.0 ± 0.3 kg/m(2)) were genotyped. Physical activity phenotypes were derived from the Paffenbarger Physical Activity Questionnaire. Analysis of covariance (ancova) tested log‐transformed differences between the IL‐15Rα genotype and physical activity phenotypes by gender with age and BMI as covariates. RESULTS: Men with the IL‐15Rα 1775AA genotype spent more time in light intensity physical activity (39.4 ± 2.4 hr/week) than men with the CC genotype (28.6 ± 2.3 hr/week, (p = .009). CONCLUSION: Further research is needed to confirm our finding and determine the possible mechanisms by which the IL‐15Rα variant modulates light intensity physical activity.