HERITABILITY OF RUNNING ECONOMY - A STUDY MADE ON TWIN BROTHERS

Running economy (RE), defined as the steady-state of oxygen uptake ((V ) over dot O-2) for a given running velocity, is a factor of sports pe rformance the genetic component of which has seldom been reported to d ate. We studied this component using a heritability index (HI) in a gr oup of 32 male twins, 8 monozygotic (MZ) and 8 dizygotic (DZ) pairs, a ll sportsmen with similar perinatal and environmental backgrounds. Zyg ocity was determined by the identity of erythrocytic antigenic, protei n and enzymatic polymorphism, and human leucocyte antigen serologic ty pes between co-twins. The subjects exercised twice on a treadmill, onc e until exhaustion and again at submaximal intensities. Pulmonary gas exchange was measured continuously using an automatic analyser system during both tests. Blood samples were obtained during the recovery per iod to determine lactate concentrations. No significant differences we re observed between MZ and DZ, in respect of RE at any speed or in max imal (V) over dot O-2 relative to body mass. Nevertheless, significant HI (P < 0.05) was found in maximal lactate concentrations (HI = 0.75) and in respiratory equivalent for oxygen at two speeds, 7 km . h(-1) (HI = 0.71) and 8 km . h(-1) (HI = 0.79), differences which probably s uggest that there are differences in RE. In conclusion, we did not det ect a genetic component in RE or in maximal oxygen uptake, but a genet ic component for markers of anaerobic metabolism was present.