ACE I/D associations were observed in these elite swimmer cohorts, with different risk alleles responsible for the associations in swimmers of different ethnicities. The functional ACTN3 R577X polymorphism did not show any significant association with elite swimmer status, despite numerous previous reports of associations with "power/sprint" performance in other sports.

Numerous reports of genetic associations with performance-related phenotypes have been published over the past three decades but there has been limited progress in discovering and characterising the genetic contribution to elite/world-class performance, mainly due to few coordinated research efforts involving major funding initiatives/consortia and the use primarily of the candidate gene analysis approach. It is timely that exercise genomics research has moved into an era utilising well-phenotyped, large cohorts and genome-wide technologies: approaches that have begun to elucidate the genetic basis of other complex traits/diseases. This review summarizes the most recent and significant findings from sports genetics and explores future trends and possibilities.

The ACTN3 R577X genotype has been found to associate with sprint/power phenotypes in all elite athlete cohorts investigated. This association has not been extensively studied in elite Asian athletes. The present study was undertaken to investigate the association between the ACTN3 R577X genotype and elite Japanese track and field athlete status. 299 elite Japanese track and field athletes (134 sprint/power athletes; 165 endurance/middle-power athletes) and 649 Japanese controls were genotyped for the ACTN3 R577X polymorphism. All athletes were of national or international level. Sprint/power athletes showed a higher frequency of RR + RX genotype than controls (111/134 [82.8%] vs. 478/649 [73.7%], P = 0.025 under the R-dominant model), while there was no significant difference between endurance/middle-power athletes and controls (126/165 [76.4%] vs. 478/649 [73.7%], P = 0.48 under the R-dominant model). Sprinters with the RR + RX genotype had significantly faster personal best times for the 100 m than those with XX genotype (10.42 ± 0.05 s vs. 10.64 ± 0.09 s, P = 0.042); no such association was found in the 400 m sprinters (47.02 ± 0.36 s vs. 47.56 ± 0.99 s, P = 0.62). ACTN3 R577X genotype is associated with sprint/power performance in elite Japanese track and field athletes, especially short sprint performance.

Purpose It has been hypothesised that certain mitochondrial haplogroups, which are defi ned by the presence of a characteristic cluster of tightly linked mitochondrial DNA polymorphisms, would be associated with elite Japanese athlete status. To examine this hypothesis, the frequencies of mitochondrial haplogroups found in elite Japanese athletes were compared with those in the general Japanese population. Methods Subjects comprised 139 Olympic athletes (79 endurance/middle-power athletes (EMA), 60 sprint/ power athletes (SPA)) and 672 controls (CON). Two mitochondrial DNA fragments containing the hypervariable sequence I (m16024-m16383) of the major non-coding region and the polymorphic site at m.5178C>A within the NADH dehydrogenase subunit 2 gene were sequenced, and subjects were classifi ed into 12 major mitochondrial haplogroups (ie, F, B, A, N9a, N9b, M7a, M7b, M*, G2, G1, D5 or D4). The mitochondrial haplogroup frequency differences among EMA, SPA and CON were then examined. Results EMA showed an excess of haplogroup G1 (OR 2.52, 95% CI 1.05 to 6.02, p=0.032), with 8.9% compared with 3.7% in CON, whereas SPA displayed a greater proportion of haplogroup F (OR 2.79, 95% CI 1.28 to 6.07, p=0.007), with 15.0% compared with 6.0% in CON. Conclusions The results suggest that mitochondrial haplogroups G1 and F are associated with elite EMA and SPA status in Japanese athletes, respectively.