Numerous studies have identified the power (RDF) developed in the upper body as an important determinant of performance in cross-country skiing races. (Gaskill et al., 1999; Heil et al., 2004; Mahood et al., 2001; Rundell, 1995; Rundell and Bacharach, 1995; Staib et al., 2000). Consequently, there are several methods used to evaluate this power, some using specific roller ski tapes and others opting for field tests or specific ski ergometers to perform these evaluations. Performance has typically been related to the time athletes run a distance, but in cross-country skiing, it’s not that simple. Finally, the FIS (international ranking) score has also been used throughout a full season as an indication of performance. This last performance indicator is very relative and lacks scientific validity.
Initially, the studies carried out on the upper part of the body to predict power have focused on the skating technique, since it was related to this modality as a technique of power and strength and not as aerobic as the old classical technique. Over the years, the idea of separating the evaluation of the human body into upper and lower parts to predict the performance and capabilities of athletes began to be appreciated. Hence the need to evaluate a cross-country skier’s double pole technique and predict his performance.
Very few studies have directly compared the power of the upper body with the maximum oxygen consumption (VO2max) in rollerski, since it is very difficult to arrive at a correct analysis of the results obtained. Evaluating a cross-country ski athlete on a roller ski on a specific treadmill is very expensive and the technical means to do it are not available in countries where this sport is almost non-existent.
On the other hand, different researchers found a strong relationship between the maximum power in watts achieved in an arm ski ergometer and the average running speed in cross-country skiers (running test on foot). The ski ergometers simulate the simultaneous movement of the arms of the double pole technique, or the movement of the arms of the alternating step in the classical technique. The athletes must pull the cables to simulate the movement and the power developed during these tests is registered by the software of these new technologies.
The scientists concluded that approximately 70% of running speed in cross-country skiing could be a consequence of the power developed by the upper body. However, many researchers claim that other methods are more effective in predicting performance in cross-country skiers, such as the time spent doing 1km alone in the double pole technique. For some of these scientists, it is the most reliable way to predict performance ahead of the VO 2max values or the lactate threshold obtained in laboratory tests.
On the other hand, other studies carried out in elite athletes of the Biathlon modality, which combines cross-country skiing in skating technique and shooting with a 22mm caliber carbine, found a high correlation between performance in a 1 km time trial cost up in double pole and the results that these athletes achieved while skiing. The same study also concluded that there is a very high relationship between IBU ranking points and the upper body power that these athletes develop, during an incremental test to exhaustion (using an arm-only ski ergometer).
Upper body training
Recent research has tried to determine the most effective training methods for developing upper body power. A number of studies have focused on maximal strength training (high loads and low number of repetitions), trying to offer an alternative to the traditional low load approach with many repetitions. These studies evaluated a traditional training program and compared it to a maximum strength training program using a single exercise that closely mimicked the double-pole movement in classical technique. The maximum strength program resulted in a considerable improvement in a 1km double pole roller-ski test, compared to the traditional low load program. The evaluated group achieved to raise the maximum strength and significantly increased the economy of effort in double pole.
The authors of the aforementioned studies suggested that because the skiers had increased their maximum strength, they performed each double pole movement with less relative cost and consequently achieved significant technical improvement. In other words, these subjects experienced an increase in the speed of contraction of their muscles and were able to generate more energy by increasing their rate of force production. The authors propose that a faster contraction means that, in a double-pole cycle, the muscle groups used spend less time working (contracting) and more time resting (relaxation).
In the wake of these findings, many cross-country ski training programs have begun to use training with high loads and Olympic lifting movements as a means of increasing maximum strength. However, it is not clear if weightlifting exercises are as effective in improving upper body power and specifically applicable to the double pole, as is the specific exercise (ski ergometer and double pole in snow or rollerski).
Conclution
In conclusion, although there is no consensus on the most effective method for developing upper-body power in cross-country skiers, recent studies have made progress towards identifying the ideal training methods for improving this physical quality. The upper body has been shown to provide 50% or more of the force required for upward thrust in skating technique, while providing 15-30% in classical technique. On the contrary, the upper part of the body can provide 100% of the necessary force on the flat in classical technique, or on gently sloping terrain, due to the use of the double pole technique. During skating technique on similar terrain, the upper body is heavily used, but the legs still contribute significantly to the movement.
Based on the studies in question, it would be interesting to evaluate the results and impact of a short and easy-to-administer upper body test on athletes. In addition, this type would probably be less detrimental to training, whereas a long test requires a recovery of several days causing problems in training. In turn, since the research comparing the effects on upper body performance with long or short tests is insufficient, it would be advisable to strike a balance in training planning in which the two types of tests are combined. This might be the most pragmatic approach until this question is investigated further.
References
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