Weight problem in ski jumping

Feb 19 2007

Dangerous underweight among top athletes can now be detected even more accurately using the new Mass Index. Unlike the Body Mass Index used in the past, this innovative method also takes into account individual leg length.

The new index was developed as part of a project by the Austrian Science Fund FWF, which had already provided the basis for resolving the problem of underweight in ski jumping. The project was based on wide-ranging field studies during the Olympic Games.

Less is more, at least when it comes to body weight and jumping distance in ski jumping, as the lighter you are, the further you fly. But when is less actually too little? When does low weight distort competition and become chronic underweight and how can these harmful developments in sport be countered?

These were precisely the issues investigated by a team led by Prof. Wolfram Müller of the Center of Human Performance Research at the University of Graz as part of the project Problems with underweight among competitive athletes. One of the results is a much improved facility for assessing underweight and overweight. The new measure for determining relative body weight is called the Mass Index (MI) and in the future it will augment or even replace the Body Mass Index (BMI), which does not take into account the proportions of the body and, in particular, individual leg length.

With his new method, Prof. Müller offers more precise calculation of relative body weight, as he explains: "So far - based on the BMI calculation - people with long legs are assessed as too thin and, conversely, people with extremely short legs are quickly branded as overweight. However, both of these assessments are incorrect as the calculation method is based simply on a person's size. In contrast, the Mass Index calculated by us takes into account the ratio between the legs and the upper part of the body.

The results obtained in this project have already led to a reduction in problems with underweight for ski jumpers. Studies of athletes physical build in connection with aerodynamic measurements and calculations persuaded the International Skiing Association to change the ski jumping regulations from the 2004/05 season onwards. Extremely light athletes are now obliged to jump with shorter skis. Since this new competition rule was implemented, practically no more underweight jumpers have got themselves into this condition through starvation. This means it is the athletes skill that will count in future and not the advantages of being underweight.

The varied project results were only made possible by comprehensive studies supported by the Olympic Committee and the International Skiing Association. Prof. Karl Sudi, who developed the project with Prof. Müller, says: We had a great opportunity during the 2002 Olympics in Salt Lake City to conduct a field study on athletes' individual flight styles and at the same time to examine the proportions and composition of ski jumpers'bodies. The involvement of nearly all the ski jumpers who started at the games meant it was possible to create the basis for changing the rules in ski jumping

It is particularly pleasing that athletes too ultimately benefited from this FWF project. Following measurements in wind tunnels, completely new forms of training were developed which make a key contribution to optimizing the performance of ski jumpers and athletes in the Nordic combined discipline. Eight athletes who took part in these forms of training won gold at the Olympic Games in Turin.