Muscle-specific creatine kinase gene polymorphism and (V)over-dot-O-2max in the HERITAGE Family Study

This study examined the association between a DNA polymorphism in the muscle-specific creatine kinase (CKMM) gene and (V) over dot O-2max in the sedentary state, as well as its response (Delta(V) over dot O-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. (V) over dot O-2max was measured during maximal cycle ergometer tests. (V) over dot O-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 Delta(V) over dot O-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 (V) over dot O-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. Delta(V) over dot O-2max values adjusted for age, sex, (V) over dot O-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 Delta(V) over dot O-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 Delta(V) over dot O-2max. These results indicate that the NcoI polymorphism in the 3' untranslated region of the muscle-specific creatine kinase gene is associated with the Delta(V) over dot O-2max to endurance training.