LONDON, U.K.--A single gene may strongly influence whether an athlete will excel at sprinting or at running long distances, new research shows. Researchers think the gene--which codes for an enzyme that regulates blood pressure and many metabolic functions--may determine whether a person tends to grow more "fast twitch" or "slow twitch" muscles.
Angiotensin converting enzyme (ACE)--dubbed the "performance gene" in 1998--comes in two alleles. The D allele, which is missing 287 base pairs, increases blood pressure and reduces mechanical efficiency of trained muscles relative to the I allele. To examine the effects of both versions, geneticist Hugh Montgomery and colleagues at University College London studied a group of 78 recruits in the British Army. They were perfect subjects, Montgomery says, because they all underwent the same 10-week basic training program, minimizing existing environmental influences. Genes appear to make a big difference: After the training, recruits with two I alleles were able to curl a barbell for 11 times as long as those with two D versions of the gene, Montgomery reported here Friday at a meeting called "Genes in Sport."
ACE may affect the type of sports people excel in too, according to Montgomery's surveys of elite British athletes. The I version is found more frequently in 5000-meter runners and high-altitude mountaineers than in the general population, but DD athletes are more common among swimmers and 200-meter runners. Montgomery speculates that the D version encourages growth of "fast twitch" anaerobic muscle fibers, which generate brief bursts of high-octane power, whereas the I version favors the "slow twitch" fibers ideal for long stretches of efficient motion. But he's not sure how the ACE gene would determine muscle fiber type.
Alex MacGregor, an epidemiologist at St. Thomas' Hospital in London, cautions that the study shows only an association--not airtight proof that the ACE gene itself stacks the deck for athletes. And even if it does, better muscle performance is just one of many keys to athletic success. "It's difficult moving from a muscle type to getting a person up a mountain," MacGregor says.
Montgomery agrees that genes don't seal an athlete's fate; for one thing, he has ambitions to climb Mount Everest himself, despite his DD genotype. But if his theory is right, his genes may well make it harder for him to reach the top, he says.
--BEN SHOUSE
Related sites
Hugh Montgomery's Web site
Medical facts about high altitude
Links to articles on running physiology and performance
Conference Web site
