The Winter Olympics boast a wide variety of sports, from rather sedate-looking curling to fast-and-furious speed skating. So is one type of athlete fitter than another?
It's hard to say. Olympic athletes are, as a rule, mind-bogglingly fit. Many Olympic athletes train for up to seven hours a day. But what fitness means depends on the sport. A bobsledder has the strength and power to push a 400-lb. (180 kilograms) sled as fast as possible for about five seconds; a cross-country skier has the endurance to glide for up to 9 miles (15 kilometers). It's impossible to say one is fitter than the other, sports physiologists and trainers agree.
Fitness "is like art and beauty," said Carl Foster, a professor of exercise and sports science at the University of Wisconsin–La Crosse. "Everybody sort of knows what it is when they see it, but defining it is pretty difficult." [Olympic Countdown: Winter Sports and Strength]
Picking from the menu
The textbook definition of fitness usually describes a menu of five components: cardiovascular endurance, muscular endurance, muscular strength, flexibility and body composition (the ratio of fat to muscle), Foster told Live Science.
For someone who is not an Olympic athlete, a good balance of these components marks fitness. But athletes are specialists, said Foster, who worked with the U.S. Olympic speed-skating team from 1979 to 2002. These athletes train the aspects of fitness they most need for their sport, he said.
Bobsledders, skeleton athletes and lugers are all "sprinters on ice," said Brad DeWeese, a professor of kinesiology, leisure and sports studies at East Tennessee State University and the strength, speed and conditioning coach for nine athletes and two alternates traveling to the Sochi Games. They train for muscular strength so they'll be able to accelerate quickly and build the momentum they need to get downhill quickly. Cardiovascular endurance is less important for this sport.
Cross-country skiers and biathletes, who compete in endurance-based challenges, use strength training to reduce fatigue, but their main focus is aerobic exercise to build cardiovascular endurance, DeWeese told Live Science. (11 Surprising Facts About the Circulatory System)
In contrast, athletes like figure skaters and downhill skiers might have a more balanced regimen, as they need endurance to complete long events, as well as the strength and flexibility to handle jumps and landings, said Ambrose Serrano, head strength and conditioning coach for the U.S. Olympic Committee at the Lake Placid, N.Y., Olympic Training Center.
These athletes may even vary on a cellular level. When a person strength trains, his or her messenger RNA, the molecule that translates DNA instructions inside the cell, alters its signal, calling for the creation of stronger, faster muscle cells, DeWeese said.