Cross-Country Skiing Injuries and Biomechanics

Summary

Cross-country skiing exercises most of the joints, muscles and tendons in the body giving the skier an all around workout. This, in combination with a low incidence of injury, makes cross-country skiing an ideal recreational and competitive sport.

The new skating techniques developed during the last decade have resulted in greater velocity. The maximum speed during the diagonal stride technique is 6 m/sec compared to 8 to 9 m/sec when skating and double poling.

Top-level skiers today use strong and ultra light skis of fibreglass and graphite. The ski weight is less than 500g. Today’s skating technique does not require any waxing and only the cambered portion of the ski is waxed when performing the diagonal stride. The preparation of the ski course has improved with the development of special track machines. This allows top-level skiers to reach 60 to 80 km/h on downhill slopes, which has resulted in an increased risk of injury.

Because cross-country skiing takes place wherever snow is available, it is difficult to establish accurate injury rates in comparison to alpine skiing which is performed on very specialised terrain at ski areas. Studies estimate the cross-country ski injury rate in Sweden to be around 0.2 to 0.5 per thousand skier days. A prospective study of cross-country ski injuries conducted in Vermont revealed an injury rate of 0.72 per thousand skier days.

75% of the injuries sustained by members of the Swedish national cross-country ski team during 1983 and 1984 were overuse injuries while 25% resulted from trauma. The most common overuse injuries included medial-tibial stress syndrome, Achilles tendon problems and lower back pain. Most common among traumatic injuries were ankle ligament sprains and fractures, muscle ruptures, and knee ligament sprains. Shoulder dislocation, acromioclavicular separation and rotator cuff tears are not infrequent in crosscountry skiing. Injuries to the ulnar collateral ligament of the metacarpal phalangeal joint of the thumb (Stener’s lesion) is the most common ski injury involving the upper extremity. Cross-country skiers 16 to 21 years of age complained more frequently of mild lower back pain than similarly aged non-skiers. This may result from repetitive hyperextension motions during the kick phase and the recurring spinal flexion and extension during the double poling phase. Repeated slipping on hard and icy tracks infrequently produce partial tears or microtrauma in the muscle tendinous units of the groin. Femoral neck fractures may be sustained after directive trauma to the greater trochanter when the skier falls to the side on hard snow or ice. These fractures are especially serious in young people. Fractures of the tibia and fibula are less frequent in cross-country than in alpine skiing, but still occasionally occur.

Injuries to the knee joint are not uncommon in cross-country skiing. Tears of the medial collateral and the anterior cruciate ligaments are complex injuries which frequently require surgical repair or reconstruction and long rehabilitation. Return to cross-country skiing can be, however, part of the rehabilitation of knee ligament injuries for cross-country skiers. In falls which include twisting, lateral dislocation of the patella can occur. Pre-patellar bursitis and fractures of the patella can result from trauma sustained by direct blows against hard ice or snow. Patellofemoral pain syndromes may be experienced especially during skiing downhill because the increased knee flexion angle requires greater forces generated by the quadriceps muscles, which in turn results in greater stress between the patella and femur.

Medial-tibial stress syndrome is a painful condition which frequently occurs along the medial border of the tibia in top-level skiers. An anterior compartment syndrome is not uncommon in skiers performing endurance training or prolonged episodes of the skating technique. Achilles tendon problems are not uncommon, especially when changing from skiing to running. In the foot, stress fractures and plantar fascitis are part of the ski injury panorama. Arthritis of the metatarasal phalangeal joint of the great toe because of dorsiflexion stress is a common problem in seasoned cross-country skiers.

Corneal abrasions may occur when the skier strikes vegetation near the ski trail. Conjunctivitis, keratitis, snow blindness and poor contrast vision can be caused by excessive overexposure to sunlight.

Superficial frostnip or frostbite are potentially serious injuries. Inhalation of large volumes of cold, dry air can result in uncomfortable breathing. Cold air may also produce rhinorrhoea, bronchorrhoea, and exercise-induced asthma. Urinary tract infection and prostatitis are not uncommon in cross-country skiers.

The capacity for prolonged heavy muscular work is greatly dependent on the ability to store large quantities of glycogen. Before longer races it is important as part of the preparation to increase the glycogen stores. The skier should substitute for large fluid losses by drinking frequently during long episodes of skiing.

The recent revolutionary developments in skis, poles, tracking machines, and techniques have contributed to increased velocity and aggressiveness in cross-country skiers. Overuse injuries have become more common in cross-country skiers, but they remain infrequent compared to those associated with running. The overall incidence of injuries resulting from cross-country skiing is quite low, thus making this sport an ideal recreational activity.