After months of uncertainty, the 2022 Winter Olympic Games are finally here. Beginning February 3, 2022, more than 3,000 athletes from around the world will convene in Beijing, China, to glide, jump, and spin their way toward gold.
The Games will be broadcast live on NBC, the NBC Sports app, and can be streamed via the Peacock app. Limited coverage can also be found on USA Network and CNBC.
While you watch, keep your eyes peeled for some of this exciting sports science at play, from the skills needed in the biathlon to the precision necessary in curling!
Biathlon: Cross-country skiing. . . with shooting
Biathletes have the unenviable task of being the best in the world at not one, but two sports. A biathlon course comprises several 3–4 km loops, taking 15-45 minutes to ski, all while the athlete’s heart rate is jacked up to 90% of its max, or up to 180 beats per minute. Amidst this heart-pounding race, he or she must stop several times to execute the second sport: rifle shooting.
Every biathlete skis with an 8-pound, .22-caliber rifle strapped to their back. At each range (two to four, depending upon the event), the athlete takes five shots at a target positioned half a football field away. They must hit the target with all five shots or ski a 150-meter penalty lap for each shot missed.
When the biathlete shoots in a standing position, the target is 11.5 cm wide, or slightly larger than a softball. When in a prone position (laying down), the target they have to hit is smaller—about the size of a golf ball. However, in this position they can use the ground to help stabilize their arms, and thereby the rifle. Whether standing or prone, the athlete needs to stay very still to shoot accurately. He or she only has wiggle room of .026 degrees (.089 degrees when standing) to make the shot.
“Part of the difficulty is the mental switch you have to do from something that is extremely dynamic and physiologically very demanding, and turn it off, forget about it, and do something that is entirely static and entirely mental,” said Joanne Firesteel Reid, a 2022 Olympic biathlete competing for the United States. “It’s that switching part that makes our sport so unique and so interesting. And really really fucking hard.”
How do snowboarders and skiers land jumps without breaking their legs?
Picture a big air competition, where a skier or snowboarder rockets down a steep ramp (40 degrees downward at its max)and then launches 30-45 feet into the air. What goes up must come down; yet when these athletes land, the impact is considerably less than a figure skater, who has only jumped a foot or two in the air but lands with a force 5-8 times their bodyweight. The difference, you might expect, is in the landing surface.
Tracks for ski and snowboard jumps have been specially engineered and built with landing in mind. “This isn’t just some random hill with a ramp,” said John Eric Goff, professor of physics at the University of Lynchburg and author of Gold Medal Physics. The jump arc follows a path similar to a parabola, which is a symmetrical curve that looks like an upside-down U. When the athlete flies into the air, he or she is going up the hump of the upside-down U, and when they land, they’re coming down the other side.
“Whenever they’re getting close to the ground, they’re actually falling along the slope of that ground. It’s not a level horizontal ground that they’re smacking into,” Goff said.
In other words, thanks to their landing at an angle that’s a little over 30 degrees (as opposed to 0 degrees), the vertical component of the athlete’s velocity is not brought to a complete stop; the “collision” is stretched out over a greater distance—the way, in a car crash, an airbag extends the collision time between your nose hitting the steering wheel.
And thank goodness for that.
The right blade for the job
Think of your knife set: If you wanted to be a world-class bread cutter, you’d use the best serrated knife available. But you wouldn’t use that same blade if you wanted to be the best vegetable chopper or meat carver. The same goes for ice skates—different sports require different blades. Here’s a quick breakdown:
Hockey: A shorter blade with rounded edges allows hockey players to turn and swivel quickly. The hollow or “radius” (which refers to the distance between the perimeter and center of the grinding wheel that forms the hollow) carved out of the solid blade gives it two edges that can “bite” into the ice and generate friction needed for stability, turns, and stops.
Figure skating: Because they plan their routines, figure skaters don’t need quite the same degree of agility as hockey players, so their radius is larger, producing a shallower hollow. This decreases friction, optimizing for glide over quick cuts and turns. The toe pick is used to dig into the ice and generate the friction a skater needs to launch into a jump or come to a stop for those dramatic finishing sequences.
Speed skating: Speed skates have long, solid blades without a hollow. This design provides more surface area contact between the blade and the ice. More contact means more friction, and more friction generates more heat, which slightly melts the ice and helps with gliding. More contact also means more area to which the skater can apply force—and the more force they apply, the faster they can go. A speed skater for long track can reach speeds of over 35 mph.
Figure skating: Triples to quads to quints
Every few Olympic cycles, skaters seem to add another rotation to their jumps. In the early 1900s, they completed one rotation. A century later, they’re up to four.
Yet the forces they face to complete these airborne revolutions remain the same.
The first element a skater must control is angular momentum. Just before U.S. favorite Nathan Chen’s body leaves the ice, he generates downward force in order to gain vertical velocity, but he also pushes the edge of his skate sideways, away from the midline of his body. That sideways force helps him to begin twisting while he’s still on the ground, creating angular momentum. It’s estimated that a 150-pound skater performing a quad jump would generate 150 foot-pounds of torque and 300 pounds of force against the ice as he leaps into the air. (If you want to know what 300 pounds of force feels like, try jumping off your kitchen table and landing with your knees locked. Ouch.)
The next element is the skater’s moment of inertia. This is a measure of how mass (e.g., a skater’s arms and legs) is distributed around a rotational axis (the invisible line running from the skater’s head to his feet). As Chen pulls his arms and legs tight to his body, the distance of mass from the rotating axis is smaller, so the moment of inertia shrinks, and he spins faster. It isn’t easy; that 150-pound skater has to exert 180 pounds of force to pull in their arms. You typically won’t see if they’ve succeeded at this on screen, but if you hear a commentator say a jump was “underrotated,” especially after a skater falls, one cause is a “too-large” moment of inertia.
The third and final element affecting the number of rotations a skater can complete in the air is the height of the jump. “We’re not in the international space station, so you only have so much time to get your rotations in,” said Deborah King, a professor of exercise science and athletic training at Ithaca College. “The height of the jump is going to be the number one variable influencing your time in the air.”
Men jump, on average, over 20 inches off the ice—four inches higher than women. As a result, men get more time in the air, although it’s still typically less than a second. This difference in height and time helps to explain why quadruple jumps have become commonplace in men’s top-level figure skating, while women are only just beginning to complete quads in competition.
As for quints, King is optimistic.
“I definitely think they can, purely from a math standpoint and also looking at the potentials of height and potentials of moment of inertia,” King said. “Skaters are practicing them without a doubt. I think we’re almost at the point where someone’s going to try one in competition to get it officially counted.”
Not all ice is equal
Ice temp: 14-21 F | Ice thickness: 2.5-3 cm
Long track speed skating requires the densest, hardest ice possible. That’s why it’s kept the coldest of all Winter Olympic ice sports, and the water used to form it is filtered of nearly all minerals.
Ice temp: 19-26 F | Ice thickness: 3 cm
Water quality also matters for curling ice. “Really pure water freezes better, flatter ice,” said Lance Wheeler, a materials scientist at the National Renewable Energy Laboratory who competed at the Olympic trials for curling. Once frozen, the ice is scraped with an 8-foot-long razor blade until it’s no more than 1/8” difference across 50-100 feet. Finally, “ice pebbles” 1-2mm high and 3-10mm wide are manually sprayed across the surface to decrease friction when the stone glides across.
Ice temp: 19-23 F | Ice thickness: 2.5-3 cm
Ice hockey rinks are resurfaced using a machine called a Zamboni, named after the Californian inventor Frank Zamboni. A Zamboni scrapes the ice, uses water to flush any debris out of crevices, vacuums up the dirty water, and puts down a thin layer of hot (140 to 145 F) water, which freezes and creates a smooth surface.
Ice temp: 26-28 F | Ice thickness: 4.5-5 cm
Figure skaters need the warmest, thickest ice of all Winter Olympic sports in order to penetrate the ice with their toe picks for jumps. Keeping the ice warmer also makes it less likely to shatter when the skater lands the jump, which can generate more than half a ton of landing force.
Ice temp: 23 F | Ice thickness: 2-5 cm
Bobsleigh, luge, and skeleton run on a 1,450-meter-long ice-covered track. Approximately 80% of the track is vertical, enabling athletes to capitalize on gravity as well as the propulsive forces they generated at the start of their runs. The ice on this track accepts forces exceeding 6,900 pounds and up to 5Gs.
Curling: How does sweeping work?
In curling, sweeping is all about friction. . . or lack thereof.
The essence of the game is as follows: teams take turns pushing (“throwing”) an up-to-44-pound granite stone down a sheet of ice toward a target called a “house.” At the end of the game, the team with the most stones closest to the house wins.
The way the stone makes its way to the house is where friction comes in. As a stone glides forward over the ice, it will start to turn, or “curl,” due to differences in friction based on how it “leans” when it travels (the front edge digs in more). To try and guide this movement, two teammates use brush-like brooms to “sweep,” or scrub, the ice. Heat caused by the friction of the broom against the ice melts a thin layer of ice, and the water acts as lubricant, both delaying the curling and helping the stone travel farther.
“The best sweepers in the world take a brush-like thing, and they’re almost planking onto that brush because the more downward force you have, the more friction you have on the ice, the more you melt the ice,” said Lance Wheeler, a materials scientist at the National Renewable Energy Laboratory who competed at the Olympic trials for curling. Don’t expect to see this melting in action, though; the water layer is on the order of 100 nanometers thick.