Physiology of alpine skiing

The extreme environment of cold, altitude and movement complexity makes alpine ski racing a difficult sport to study. This review comprises >30 years of research and includes 29 on-snow investigations of specific physiology relating to the various ski racing disciplines, nine off-snow investigations of the physiological capacities of ski racers of varying ability and four review articles. Alpine ski racing appears to involve a complex integration of many different physiological systems, none of which may be more important than the other to overall performance. While technical ability appears to be the greatest influencing factor on performance, the ability to continually exhibit technical competence through a long competitive season requires high capabilities within all physiological systems. Identifying the optimal approach and time to concurrently develop these systems is a challenge for sport scientists. Further research is required using modern portable investigative tools for determining aerobic and anaerobic demands and abilities, especially in the areas of muscle function and relative energy system contribution during both single and multiple runs on varying terrain.     

Alpine skiing injuries.

Alpine skiing accidents admitted to the Trondheim Regional and University Hospital during one year were recorded. Of the 339 injured, 67 per cent were male and 33 per cent were female. Eighty-seven per cent were outpatients, and 13 per cent were hospitalized. Falling accidents (67 per cent), followed by collision accidents (17 per cent), were the most common cause of injury. The injuries in the lower extremities were caused by falling and the head injuries were mostly caused by collisions. Knee ligament strains were the most common injuries, and 17 per cent of these were hospitalized and required operative treatment. Of the minor knee strains, all 44 per cent were not fully recovered after two and a half years. Seventeen patients sustained tibial fractures, eleven of them spiral fractures and six transverse fractures. The patients with spiral fractures were younger than the patients with transverse fractures. Head injuries were the most severe injuries, with eleven concussions and two epidural haematomas.     

Alpine skiing and acute beta-blockade

The effect of acute unselective (propranolol) and beta 1-selective (atenolol) beta-adrenoceptor blockade was studied on alpine skiing in six leisure and seven elite skiers. Prior to the skiing tests a short time "all out" cycle ergometer test (Wingate muscle power test) was performed to confirm whether a beta-blocking effect (80 mg propranolol and 100 mg atenolol orally) was present or not. Peak and average power of the Wingate test showed an impairment in the order of 4%--6% (P less than 0.05--0.001). Peak blood lactate was only reduced after propranolol (0.05 greater than P greater than 0.01). During leisure skiing under submaximal exercise conditions peak blood lactate was increased (P less than 0.05) as compared to placebo, but rated perceived exertion (RPE) was unchanged as well as the estimated skiing technique. The elite skiers showed prolonged performance times (P less than 0.05) after beta-blockade and in the case of propranolol also reduced peak and mean blood lactates (P less than 0.05). It is suggested that during intense exercise propranolol reduced lactate formation, which is in line with previous reports. This might impair short time, "explosive" type muscular exercise. If there is a risk factor for injury during beta-blockade and alpine skiing, it might be connected to the impaired performance and metabolism in relation to intense exercise and propranolol treatment.     

Alpine skiing and the mature athlete.

Alpine skiing is a popular sport enjoyed by millions of Americans annually. As the average age of the world population increases, so does the average age of the skier. The ever-increasing older group of skiers adds a new dimension to both the prevention and treatment of ski injuries. Several injuries, if not unique to the older skier, are more common in this group, and familiarity with the causes, treatments, risks, and avoidance of these injuries is essential for proper treatment. It is possible that with proper education, prevention, and physical training, the incidence of these injuries can be decreased to the level of the general population, and skiing will not be more hazardous to the older athlete.     

Hemoglobin/myoglobin oxygen desaturation during Alpine skiing

PURPOSE: To investigate muscle blood volume (BV) change and hemoglobin/myoglobin oxygen desaturation (OD) during simulated giant slalom (GS) and slalom (SL) Alpine ski racing. METHODS: Joint angle, BV, OD, and heart rate (HR) were evaluated during GS and SL events in 30 junior elite skiers ages 9--17 yr (13.5 +/- 2.3). Subjects were stratified by ski class and age: group I, J1 and J2, ages 15--18 yr (16.8 +/- 0.8); group II, J3, 13--14 yr (13.6 +/- 0.7); and group III, J4 and J5, 9--12 yr (11.5 +/- 1.2). Near-infrared spectrophotometry (NIRS) was used to measure BV and OD in the capillary bed of the vastus lateralis during trials. Maximal OD was determined during thigh cuff ischemia (CI). Quadriceps cross-sectional area (CSA) was estimated by skin-fold and thigh circumference. RESULTS: Joint angles were smaller (P < 0.05) during GS than SL for ankle (83.8 +/- 11.9 degrees; 98.6 +/- 15.7 degrees ), knee (107.4 +/- 14.9 degrees; 118.3 +/- 18.0 degrees ), and hip (98.8 +/- 14.3 degrees; 107.5 +/- 16.2 degrees ). BV reduction from rest to peak exercise (Delta BV) was 30% greater (P < 0.05) during the GS than SL, whereas Delta OD was 33% greater (P < 0.05) during GS. Delta OD, relative to CI OD, was greater for all subjects during GS (79.2 +/- 3.7%) than SL (65.7 +/- 4.4%). This pattern continued within groups; group II displayed the greatest relative desaturation (82.9 +/- 7.6%). CSA was larger in older skiers (92.5 +/- 21.6; 72.5 +/- 12.3; 65.3 +/- 21.2 cm(2)) and correlated with Delta OD (P < 0.05). CONCLUSION: The larger reduction in BV (Delta BV change) and greater OD when skiers assumed lower posture during GS than SL may be related to greater effective static load secondary to higher percent of maximal voluntary contraction and is consistent with compromised blood flow to working muscle.     

Calculation of the contact pressure between ski and snow during a carved turn in Alpine skiing

The macroscopic contact area between ski and snow and the contact pressure are crucial influencing factors for carved turns in Alpine skiing. In the present paper, a simulation model is developed to quantify these factors. The ski is modelled as an Euler–Bernoulli beam with variable cross section, camber, bending and torsional stiffness using measured data from skis. The reaction forces of the snow are decomposed in penetration and shear forces. For the penetration forces a hypoplastic constitutive law is applied incorporating elastic and plastic deformation of the snow at the contact area. For the shear forces metal cutting theory is used. Ski deformation, contact area and contact pressure are computed based on quasi‐static equilibrium between forces exerted by the skier and snow reaction forces. Parameter studies are performed to investigate the influence of edging and distributing the load between the inner and outer ski. Higher edging angles as well as loading both skis affected the contact pressure positively by increasing the resistance against shearing. The results of our study agree well with measurement data taken from literature. Based on the results, the importance of actions of the skier during carved turns is concluded.     

Downhill skiing injuries and their cost at a Finnish skiing area

During the 1987–1990 ski seasons. 325 consecutive patients sustained downhill skiing injuries at a skiing area in central Finland. The calculated injury rate was 0.94 per 1000 skier-days (0.9%) and 0.56 per 1000 skiers (0.06%). Forty-one percent of the injuries were located in the lower limbs and 37% in the upper limbs. Sprain was the most common type of injury (34%), followed by fractures (22%) and contusions (17%). Only 7% of the patients needed surgery. The estimated mean cost of medical treatment and sick leave was FIM 5500 (USD 1400) per patient.     

Effect of skiing speed on ski and pole forces in cross-country skiing

PURPOSE: The present study characterized pole and ski forces in classical technique cross-country skiing. Eight elite junior cross-country skiers performed diagonal skiing at 65%, 75%, 90%, and 100% of maximum speed on a stable 100-m-low uphill (2.5 degrees ). METHOD:: The ski and the pole forces (vertical (Fz) and horizontal (Fy) directions) on the right and left sides were recorded separately when the skier skied over a special custom-made force platform system placed at the end of the uphill course. The entire system consisted of four separate 20-m-long rows of 1-m-long force plates connected in series, row by row. RESULTS: When the forces were averaged for the various functional phases of skiing cycle, the ski Fz during the gliding phase decreased and the braking ski Fy and Fz remained the same with higher skiing speed. During the subsequent kick phase, both ski Fy and Fz increased significantly as a function of the skiing speed. Consequently, the Fy ratio between the ski and the pole plant increased with faster skiing speed. Simultaneously measured EMGs from five different muscles showed that the abdominals had a pattern of increasing activation with increase in speed of skiing. All the other muscles, vastus lateralis (VL), rectus femoris (RF), erector spinae (ES), and medial gastrocnemius (MG), were obviously active in the preloading and the kick phases. CONCLUSIONS: The speed dependence of the ski and the pole force distributions in the present study are important for further understanding of the complexity of cross-country skiing. Especially relevant is to use these results as basis for studies aimed at better understanding of the propulsive force production, when more comprehensive EMG analysis is complemented with simultaneous kinematic recordings at varied slope, speed, and waxing conditions.     

Cervical injury from skiing

A retrospective study of 18 patients with cervical spine injuries from skiing accidents is presented. Four patients were treated surgically because of instabilities. Twelve patients had associated head injuries, two of whom were operated on. One patient died from severe craniocervical injury caused by collision with another skier. The causes of the cervical spine injuries are analyzed and the possibilities for preventing them are presented.     

Injuries in powder skiing

A Norwegian multicentre study of the winter 1985-1986, when 328 injured skiers were compared with a control population of 316 uninjured skiers, revealed a significantly lower injury risk for skiers on ungroomed than for skiers on groomed slopes. Thirty-seven skiers were injured on ungroomed slopes, and skiers aged 15–29 years were at risk. The population of uninjured powder skiers was significantly younger than the uninjured skiers on groomed slopes. Beginners were significantly overrepresented among the injured powder skiers, but the skiing ability for uninjured powder skiers was significantly higher than for uninjured skiers on groomed slopes. In conclusion, a lower injury risk was recorded for powder skiers than for skiers on groomed slopes, probably due to a higher skiing ability of the powder skiers.     

Applied physiology of cross-country skiing

Cross-country ski racing has evolved rapidly in recent years. Of particular interest has been the development and proliferation of the faster freestyle or skating techniques. In spite of changes in technique and equipment, the fact that elite cross-country ski racers have some of the highest aerobic power values reported for endurance athletes has not changed. Successful ski racers have higher percentages of slow twitch muscle fibres and higher anaerobic thresholds, but lower anaerobic power scores than Alpine skiers. Cross-country skiers are also lean, as are distance runners. The absolute bodyweight of the ski racer, however, is much more variable than that of distance runners. Since light skiers will have an advantage on steep uphill courses and heavier skiers will be favoured by level, downhill, and less steep uphill courses, the variability of courses available in international competition explains why successful skiers are so variable with respect to bodyweight. The physiological characteristics of the elite skier are a result of both genetics and adaptation to rigorous multiyear, year-round training programmes. Identification of systematic procedures for specifically challenging the physiological parameters which are requisite for ski racing are being examined. Investigation of ventilatory and lactate thresholds as well as heart rate as parameters for quantifying training intensity is of particular interest at this time.