Linkage between a muscle-specific CK gene marker and VO2max in the HERITAGE Family Study

Purpose: We have reported a significant association between Tie,,, in the sedentary state and its response (Delta (V) over dot O-2max) to an endurance training program with a muscle-specific creatine kinase (CKMM) gene polymorphism. The purpose of this study was to test the hypothesis of genetic linkage between the same CKMM marker and (V) over dot O-2max in the sedentary state as well as Delta (V) over dot O-2max. Methods: Sib-pair linkage analysis was performed on 277 full sib-pairs from 98 Caucasian nuclear families of the HERITAGE Family Study. (V) over dot O-2max was measured during cycle ergometry tests before and after 20 wk of endurance training. The CKMM polymorphism was detected by the polymerase chain reaction and digestion with the Ncol restriction enzyme. Results: Frequencies for the rare (1170 base pairs) and common(985 + 185 base pairs) alleles were 0.32 and 0.68, respectively. No significant linkage (t = -0.02, P = 0.49) was detected between the CKMM marker and the age and sex adjusted (V) over dot O-2max (mL.kg(-1).min(-1)) in the sedentary state. However, after adjustment of Delta (V) over dot O-2max for the effects of age, sex, initial (V) over dot O-2max and body mass, evidence for linkage between the CKMM locus and Delta (V) over dot O-2max was suggestive (P = 0.04). Conclusion: The present results provide further support for the notion that the CKMM gene, or some gene in close Linkage disequilibrium with it, may contribute to individual differences in the (V) over dot O-2max response to endurance training.