Alpine skiing, or downhill skiing, is the sport or recreation of sliding down snow-covered hills on skis with fixed-heel bindings. It is characterized by the requirement for mechanical assistance getting to the top of the hill, since the equipment does not allow efficient walking or hiking, unlike cross-country skis which use free-heel bindings. It is typically practised at ski resorts which provide services such as ski lifts, artificial snow making and grooming, first aid, and restaurants. Back-country skiers use alpine skiing equipment to ski off the marked pistes, in some cases with the assistance of snowmobiles, helicopters or snowcats.
A skier following the fall line will reach the maximum possible speed for that slope. A skier with skis pointed perpendicular to the fall line, across the hill instead of down it, will accelerate more slowly. The speed of descent down any given hill can be controlled by changing the angle of motion in relation to the fall line, skiing across the hill rather than down it.
Downhill skiing technique focuses on the use of turns to smoothly turn the skis from one direction to another. Additionally, the skier can use the same techniques to turn the ski away from the direction of movement, generating skidding forces between the skis and snow which further control the speed of the descent. Good technique results in a flowing motion from one descent angle to another one, adjusting the angle as needed to match changes in the steepness of the run. This looks more like a single series of S's than turns followed by straight sections.
The oldest and still common form of alpine ski turn is the stem, turning the front of the skis sideways from the body so they form an angle against the direction of travel. In doing so, the ski pushes snow forward and to the side, and the snow pushes the skier back and to the opposite side. The force backwards directly counteracts gravity, and slows the skier. The force to the sides, if unbalanced, will cause the skier to turn.
Carving is based on the shape of the ski itself; when the ski is rotated onto its edge, the pattern cut into its side causes it to bend into an arc. The contact between the arc of the ski edges and the snow naturally causes the ski to tend to move along that arc, slowing the skier and changing their direction of motion.
Modern alpine skis are shaped to enable carve turning, and have evolved significantly since the 1980s.
During the 1930s, the Kandahar binding was introduced, which could be locked down at the heel for the downhill portions. The Kandahar remained in widespread use until the 1960s. As more skiers took up the sport, especially in the 1950s, broken legs became common. Dr. Richard Spademan saw 150 spiral fractures pass through his emergency department near Squaw Valley in three days, an event that led to the development of the Spademan binding. By the early 1950s, several safety bindings were on the market that allowed the ski to come off when the ski twisted to the side. This helped reduce the incidence of spiral fractures.
Originally boots were cut low, just over the ankle, and soft laterally, both of which limited the amount of sideways rotating force that could be applied. Around 1966, two new ski boots made of plastic came to market. Compared to leather designs, the Rosemount and Lange boots dramatically increased the amount of lateral stiffness, and in turn, the amount of edging control over the ski. Additionally, the plastic did not change shape over time or when it got wet. This allowed the bindings to be much more closely matched to the fit of the boot, and offer dramatically improved performance.
Use of helmets in skiing was rare until about 2000, but by about 2010 a majority of skiers and snowboarders in the US and Europe wore helmets. Helmets are available in many styles, and typically consist of a hard plastic/resin shell with inner padding. Modern ski helmets may include many additional features such as vents, earmuffs, headphones, goggle mounts, and camera mounts.
- Racing, comprising slalom, giant slalom, super giant slalom, combined, and downhill.
- Freestyle skiing incorporates events such as moguls, aerials, halfpipe, and skicross.
Ski trail ratings
In most ski resorts, the runs are graded according to comparative difficulty so that skiers can select appropriate routes. The grading schemes around the world are related, although with significant regional variations. Skiers should be careful to gauge the range of trail difficulty of the mountain they are skiing and select trails rated to their ability accordingly. A beginner-rated trail at a large mountain may be more of an intermediate-rated trail on a smaller mountain.
In alpine skiing, for every 1000 people skiing in a day, on average between two and four will require medical attention. Knee injuries account for 33 percent of injuries. Most accidents are the result of user error leading to an isolated fall.