MUSCLE-SPECIFIC CREATINE KINASE GENE POLYMORPHISM AND VO2max TRAINABILITY IN THE HERITAGE FAMILY STUDY 1319

This study examined the association between a DNA polymorphism in the muscle-specific creatine kinase (CKMM) gene and VO2max response(Δ) to a standardized 20-week endurance training program. The subjects were 160 unrelated Caucasians (females = 80; males = 80; age = 52±5 yrs, mean±SD) of the HERITAGE Family Study. The CKMM polymorphism was detected by PCR and digestion with the Ncol restriction enzyme. VO2max was measured during maximal stationary cycle tests. Initial VO2max was 2119±608 ml·min-1 or 26±6 ml·kg-1·min-1 while the Δ reached 323±204 ml·min-1, but with a gender difference(women=283±177 ml·min-1; men=363±223 ml·min-1; t=2.5, p=0.01). Allele and genotype frequencies were not significantly different between genders. Δ values adjusted for age, gender, initial VO2max and body mass were characterized by genotype differences (F=8.4, p=0.0004). Homozygotes for the rare 1170 bp allele demonstrated a significantly lower Δ (103±201 ml·min-1, n= 12) than heterozygotes (Δ=351±216 ml·min-1; n=70) or homozygotes (Δ =331±174 ml·min-1, n=78) for the common 985+ 185 bp allele. These results indicate an almost three-fold lower VO2max response to endurance training in homozygotes for the rare 1170 bp allele and suggest that the muscle-specific creatine kinase Ncol polymorphism is associated with the VO2max response to endurance training.