Your body is a piston on skis, one fluid thrust of speed and strength ripping across the snow. Your breath is a bellows, and your heart is jangling at three beats a second. A minute later, you are prone on the snow, pressing the trigger of your rifle to the very edge of its point of release, your mind and body reaching for the most perfect stillness before the final, nearly invisible pull.

Biathlon is so named because it combines two sports: cross-country skiing and target shooting. (It originated as a Nordic military-training exercise.) But it’s not two sports. It’s one sport with two skill sets, two modes, two separate worlds as well as a transition between them — a sudden switch from pure exertion to pure focus — that demands an expertise of its own.

The dual performance is so impressive that you might assume, as sports commentators often have, that a biathlete commands her body so completely that she slows her heartbeat and then times her shots in between the pumping of her own turbocharged blood — that she has achieved a physical wizardry the rest of us can only gawk at. But that’s a fantasy. According to Jonne Kahkonen, head coach of the United States women’s team, it would take too much precious time for a heart to slow enough to create a meaningful space between beats.

What athletes can and do control is their breath, in a careful, rigid cadence, taking their shot during a minute interruption in their exhale. Yet the myth of the heartbeat shot persists. It’s one of the most common misconceptions about the sport, says Susan Dunklee, a 31-year-old American from Barton, Vt., who won a silver medal in last year’s World Cup and is one of Team USA’s top hopes for its first-ever medal in biathlon — right up there with the assumption that biathlon includes biking and swimming.

That may be because there is a kind of wizardry to succeeding in the sport. Many Olympic events, including cross-country skiing, have the same top finishers again and again. Biathlon, with its unique challenges, is different. “You can be on the podium one day and in 85th place the next,” Dunklee, a cross-country skier who had never fired a gun before the team invited her to try biathlon, told me. “You can miss and not know why. You can have monthslong slumps and not know why.” Races are won or lost on what happens on the shooting range, and the range is won or lost on what happens in your head, and that is harder to control or predict than a heartbeat. “On any given day,” says Lowell Bailey, the 36-year-old who won last year’s men’s World Cup individual championship and who is now another United States hope in Pyeongchang, “50 or 60 biathletes could win an Olympic medal.”

When Dunklee is racing, she’s in what she calls “tunnel mode” — totally closed off to anything except the race. But as she approaches the range, with its row of tiny black circles to hit or miss, she needs more information: What’s the wind doing? What shooting position will she take? “I have to open all my senses,” she says, “but then I also open myself to distraction,” things like the roar of the crowd or the good shots another athlete is taking or being close enough to the lead that hitting every one of her targets could put her on the podium. None of these thoughts, in that moment, are useful, but as Dunklee notes, that doesn’t keep you from having them.

Instead of magic, biathletes have practice. Just as they try to turn the physical part of the race into a routine — down to pinpointing the exact tree where they’ll start slowing down for the shooting range or devoting whole training sessions to removing a rifle from a harness until the motion is fluid and automatic — they try to plan for unwanted thoughts with mental drills that prepare them to dismiss distractions and refocus. Kahkonen likes to give athletes a key phrase just before the race, as simple as “trigger squeeze” or “follow-through,” a mantra to help them slip from the chaotic present into the unquestioned grooves of long practice. “You can only do what you’ve prepared to do,” Bailey says.

During a whiteout blizzard at a race in Austria in December, Dunklee missed eight of her 10 shots and finished in 97th place in a field of 102 — the opposite of how she hoped to start the World Cup and Olympic seasons. Afterward, she decided to spend a few days not thinking about biathlon.

“I don’t like the idea of deriving all the meaning of your life out of a sport,” she told me, especially one in which the outcomes are so often unpredictable. So she went to a tourist attraction in Sweden where you can pet moose. In Austria, she watched festivities for Krampusnacht, a pagan-turned-Christmas tradition that features a satyrlike beast who takes bad children to the underworld. She worked on the smooth execution of her trigger squeeze. Soon, she felt like herself. In the next race, during which she took 10 perfect shots, everything within her was still.