Muscle-specific creatine kinase gene polymorphism and VεO(2max) in the HERITAGE Family Study

This study examined the association between a DNA polymorphism in the muscle-specific creatine kinase (CKMM) gene and V̇O(2max) in the sedentary state, as well as its response (ΔV̇O(2max)) tO a standardized 20-wk endurance training program. The subjects were 160 biologically unrelated Caucasian parents (80 women, 80 men) and 80 biologically unrelated adult offspring of the HERITAGE Family Study. The CKMM polymorphism was detected by PCR and digestion with the NcoI restriction enzyme. V̇O(2max) was measured during maximal cycle ergometer tests. V̇O(2max) was 2119 ± 45 mL · min^{- 1} (mean ± SE) or 26 ± 0.4 mL · kg ^-1 · min^-1. Both sexes had a significant (P < 0.05) increase in the ΔV̇O(2max) (women = 283 ± 20 mL · min^-1 and men = 363 ± 25 mL · min^-1. Allele and genotype frequencies were not significantly different (P > 0.05) between sexes. Age and sex adjusted V̇O(2max) was significantly (P = 0.007) associated with the CKMM genotype in the parents, whereas no association (P > 0.05) was observed in the offspring. ΔV̇O(2max) values adjusted for age, sex, V̇O(2max), and body mass were characterized by genotype differences in both parents (P = 0.0004) and offspring (P = 0.0025). A significantly (P < 0.05) lower ΔV̇O(2max) to endurance training was detected in both parents and offspring homozygotes for the rare allele. The genotype accounted for at least 9% of the variance in ΔV̇O(2max). These results indicate that the NcoI polymorphism in the 3' untranslated region of the muscle-specific creatine kinase gene is associated with the ΔV̇O(2max) to endurance training.