Cross-Country Skiing




General Principles





  • Cross-country or nordic skiing is multifaceted and can be pursued either as a simple recreational outdoor activity or a vigorous competitive endurance sport.



  • Cross-country skiing serves as an excellent means to develop and maintain cardiovascular fitness; most large muscle groups of the upper and lower body are used in a smooth, rhythmic, low-impact manner.



  • Injury rates are typically lower than those seen in alpine skiing and running.



  • It is very popular in Scandinavian countries and is moderately popular in the northeastern and western mountain regions of the United States.





Cross-Country Skiing Variations


Trail/Track Skiing





  • Skiers use machine-groomed trails.



  • Trails are compacted and rolled with heavy sleds pulled by snowcats or snowmobiles, leaving a set of parallel ski tracks and an 8-by-10-foot wide and open lane for ski skating.



  • Groomed trails are standard at cross-country ski resorts. Several communities set trails on snow-covered golf courses or bike trails for local citizen use, and some are lighted for night skiing.



  • Trail skiing is suitable for a wide range of individuals, young and old, regardless of prior experience. Novices simply “ski-walk,” employing a shuffling-like technique on the snow. More experienced skiers use tracks with a diagonal stride (classic) technique or groomed lanes with a ski-skate (freestyle) technique.



  • Competitive ski racing and training require machine-groomed trails.



Backcountry Skiing/Ski Touring





  • No groomed trail is required.



  • Participants choose their own route (i.e., bushwhacking). Certain enthusiasts pursue a midday trek in the woods and a picnic lunch, while others plan a multiday snow camping tour, and still others seek out backcountry slopes to climb and then descend using a telemark turn technique.



  • A telemark turn is one wherein the skier thrusts the outside (or downhill) ski forward, assuming a lunge position with the front knee at approximately 90 degrees of flexion and the back knee in a kneeling position. The turn is carved while holding this position.



  • Backcountry skiers typically choose skis with metal edges and relatively heavy, supportive boots.



Chair Lift–Facilitated Telemark Skiing





  • Could be considered a variant of alpine skiing; participants opt for a chair lift at a ski area to repeatedly transport them to the top of a slope and then descend while making telemark turns (in contrast to the parallel turns of alpine skiers).



  • Skiers use stiff plastic boots, wide metal-edged skis with a significant side cut, and strong three-pin or riveted toe cable bindings that still allow the heel to lift freely off of the ski. The three-pin and most other cable bindings are not designed to release during a fall, although newer binding designs do release.



  • Skilled telemark skiers often reach speeds similar to alpine skiers and are subject to similar injuries.





Competitive Cross-Country Skiing


Race Events





  • There has been a recent trend toward using audience-friendly formats such as mass-start, sprint, relay, and pursuit (a race that involves switching skis and styles midway through the race).



  • Venues for major ski races (e.g., the 2002 Winter Olympic venue at Soldier Hollow, Utah) have been designed to allow better spectator viewing, with large sections of the course visible from the stands.



  • World Cup and Olympic race events include (distance format for women and men, respectively) 1 km sprint, 2 × 1 km team sprint, 10 km/15 km individual start, 15 km/30 km pursuit, 30 km/50 km mass start, and 4 × 5 km/4 × 10 km relay.



  • Citizen race distances vary from 5 to 55 km. Certain races are specifically designated as classical technique only, whereas most use a freestyle format.



  • The largest event in the United States is the American Birkebeiner in northern Wisconsin (52 km, with >7000 participants).



Equipment


Diagonal Stride (Classic)





  • Skis: Double camber, with central area for kick wax (waxless skis have a “fish scale” pattern imprinted on the ski base); when the skier’s weight is evenly distributed between skis, the central kick zone should not contact the snow, thus allowing maximal glide. When the ski is aggressively weighted, the kick zone is engaged in the snow, thus allowing a push-off, or “kick.” Skis are typically 20–25 cm greater than the skier’s height, but the skier’s weight should also be considered when choosing ski length and ski flex.



  • Boots: Lightweight, relatively low cut, flexible sole



  • Bindings: Currently, there are two predominant systems: New Nordic Norm (NNN) and Salomon Nordic System (SNS). Both are lightweight and engage the ski boot at the toe alone, allowing the heel to lift freely off of the ski while striding. The two systems primarily differ by the ridges on the binding plate that fit into corresponding slots on the boot’s sole.



  • Poles: Carbon fiber (preferred by elite skiers) or aluminum, with variable grip and strap systems. Pole length extends to a height between the skier’s armpit and top of shoulder.



Ski Skating (Freestyle)





  • Skis: Typically 10–15 cm shorter than classic skis, with more torsional rigidity to accommodate the forces generated during skate push-off; ski design continues to evolve, particularly in relation to side cut and ski tip shape. Racing ski bases have specified “grinds” to enhance glide wax absorption and maximize glide when matched to specific snow conditions.



  • Boots: Skate boots are cut higher, with a stiffer upper boot that is hinged at the ankle, and provide more lateral support than classic boots. Skate boots also have a more rigid sole.



  • Bindings: Similar to classic bindings, but with a more rigid toe plate; the SNS Pilot system has a second attachment point to the boot under the toe that operates as a spring-loaded hinged plate and provides slightly more control over the ski.



  • Poles: Carbon fiber (best) or aluminum, with variable grip and strap systems, slightly longer than classic poles; typical height of a skate pole is skier’s midchin.



Ski Base Preparation





  • Ski glide: Considerable effort is directed at maximizing ski glide during cross-country ski competitions. Most elite skiers carry several different pairs of skis with variable base compositions and stone ground patterns, or “grinds,” each best suited to a particular snow condition. A “rill” pattern may also be pressed onto the ski base to facilitate channeling of melting snow and reduce friction on particularly warm and humid days.



  • Glide wax: Typically applied to the entire length of the base of skate skis and to the tips and tails of classic skis; layers of wax are melted in with an iron, scraped nearly clean between layers, and then the final layer is brushed and polished after it is ironed and scraped. Modern, high-performance ski waxes contain a variable percentage of fluorocarbon, typically using a higher percentage for warmer, higher-humidity conditions. 100% fluorocarbon wax, though expensive, is often used as the final layer on a fully prepped race ski, even at the citizen race level.



  • Kick wax: Applied to the center section of classic skis to provide grip for forward propulsion; waxes are specifically formulated for different temperature ranges—harder for colder snow, softer for warmer snow—and can be rubbed on like a crayon, then melted with an iron. Certain conditions (icy or warm and wet) call for Klister wax—a sticky, glue-like paste squeezed from a tube.



Clothing





  • Fabric and fit: Cross-country skiing is a highly aerobic sport. Race participants typically wear light, form-fitting, synthetic clothing, although newer merino wool and silk alternatives are available.



  • Layers: Layered clothing is a key strategy to avoid either overheating or excessive cooling that might otherwise be caused by variations in exertion or variations in weather, particularly during training or casual skiing.





Cross-Country Ski Techniques



Jul 19, 2019 | Posted by in SPORT MEDICINE | Comments Off on Cross-Country Skiing

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