1. The power of the aerobic metabolic pathway correlates well with successful physical performance in endurance sports events. The ability to alter the pathway through training presents well-known limitations, and consequently a good genetic endowment is essential to participate in elite sporting activities.
2. In 32 subjects (16 healthy pairs of male twin sportsmen, 8 monozygotic and 8 dizygotic) zygosity was determined by means of the genetic analysis of human leucocyte antigen (HLA) system specificities at class I and II loci and other genetic variants. The subjects performed a progressive exercise test on a treadmill to ascertain the maximal oxygen uptake (V̇O2max), measured by an automatic breath-by-breath analyser. We have considered the relationship between the A, B and C loci of the HLA system and V̇O2max.
3. We found a high correlation between the presence of both HLA A2 and All and V̇O2max. In the A2A11 group (n = 6) we found a V̇O2max (mean ± SD) equal to 71 ± 4 ml min−1 kg−1. The group without this pair of alleles (n = 26) showed a much lower aerobic power (58 ±5 ml min−1 kg−1). Differences between the two groups were found to be largely significant (P < 0.001). It is noteworthy that in two pairs of dizygotic twins, the higher V̇O2max value corresponded to the twin with the A2A11 allele.
4. The very marked concordance between the presence of the A2A11 locus of the HLA system and the V̇O2max could be of great interest for the identification of outstanding performers.