No matter how hard you push yourself, you probably still can’t run as fast as some of your friends. Even with tons of training, most of us could never be Olympians.

In fact, if you watch elite sprinters in action, you might think they are just born with something the rest of us don’t have. Now, new research suggests what that might be.

Speedy runners are more likely to have a certain gene than other people, say scientists in Australia. The gene tells the body to make a protein called alpha-actinin-3. This protein works in fast-twitch muscles, which provide bursts of power for activities like sprinting or speed skating.

Kathryn North of Children's Hospital at Westmead in Sydney, Australia, and her colleagues thought the protein might affect sprinting speed. So, the researchers compared star sprinters to endurance athletes and other people.

In their study, 94 percent of sprinters and speed skaters had the gene for making alpha-actinin-3. In comparison, only 82 percent of non-athletes had it. And 76 percent of marathon runners and other endurance athletes had it.

Alpha-actinin-3 might give sprinters an extra boost when they need it. And North suggests that not having the protein might help endurance athletes stay strong during lengthy exertion.

The research may eventually help explain why some people are so much faster than others.

But even if you aren’t biologically destined to break records at the 100-meter dash, keep practicing your stride. There might be marathons in your future!—E. Sohn