Fuss, Franz Konstantin

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ISEA 2022 – The Engineering of Sport 14, Purdue University, 6-10 June 2022 Corresponding author email: franzkonstantin.fuss@uni-bayreuth.de                                     1  DOES THE BODY MASS INFLUENCE THE WINNING TIME IN SKELETON AND LUGE COMPETITIONS?  Franz Konstantin Fuss Chair of Biomechanics, Faculty of Engineering Science, Bayreuth University, Bayreuth, D-95440, Germany  Introduction: The terminal speed in gravity powered sports disciplines is related to the square root of the ratio of weight to drag area [1], i.e. the greater the total gliding mass TM (athlete, gear, equipment, additional ballast) and the smaller the drag area, the faster is the speed. According to the skeleton rules [2], the total TM is restricted to 115 kg for men and 92 kg for women, including ballast masses attached to the sled. The luge rules [3] are more complex, but, in contrast to the skeleton rules, lighter athletes are disadvantaged. The aim of this study is to investigate the relationship between the athlete’s body mass BM and the glide times in skeleton and luge competitions. In a perfectly fair scenario, the BM should not have any influence on the finish time.  Methods: I used the finish times of 6 training and 4 final runs of women’s and men’s luge and skeleton competitions at the 2018 PyeongChang Winter Olympics for correlating the two best finish times of each athlete with the athletes’ BM. The required data were publicly available. Although the relationship of finish time and BM is inherently non-linear (equation 19 of [4], if the time t is the dependent variable, the mass is the independent one, and other variables including the glide distance x are constants), the actual fit curve of the data is almost linear, so that a linear regression is justified. The regressions were tested as to the fit equation (informing of the improvement of the finish time per unit mass), R2-value (informing of the influence of BM on the finish time) and its p-value. Results and Discussion: The data regressions of the 4 Olympic events are shown in Fig. 1, and the statistical data are listed in Table 1. The trends of all regressions were significant (p≤0.044), suggesting a shorter finish time as the BM increases. The influence of BM on the finish time ranged from 5% to 28%. The unexplained influence is due to the equipment + ballast mass and the skill of the athlete. From the gradient of the regression function, increasing the mass by 1 kg saves time of 22-72 ms. The practical application thereof results from the time difference between gold and silver medallist of the men’s luge competition: 26 ms over four final runs, or 6.5 ms for one run on average. Although this competition showed the lowest time-saving gradient (21.6 ms/kg), saving 6.5 ms requires merely a ballast mass of 0.3 kg under identical conditions. This study provides evidence that despite ISEA 2022 – The Engineering of Sport 14, Purdue University, 6-10 June 2022 Corresponding author email: franzkonstantin.fuss@uni-bayreuth.de                                     2  ballast mass allowance during competitions, lighter athletes are disadvantaged and/or do not make good use of ballast within the regulations. Table 1: Statistical data of the regressions shown in Fig. 1  Skeleton men Skeleton women Luge men Luge women R2 0.0764 0.2824 0.0510 0.1325 p (α = 0.1) 0.0325 0.0004 0.0440 0.0042 influence % 7.64% 28.24% 5.10% 13.25% gradient (s/kg) -0.0381 -0.0713 -0.0216 -0.0253     Fig. 1: Finish times vs athlete body mass in 4 competitions  1. Luethi S M, Denoth J (1987). The influence of aerodynamic and anthropometric factors on speed in skiing. Intl J Sport Biomech 3:345-352. 2. IBSF (2015) International Skeleton Rules. Lausanne, Switzerland 3. FIL (2014) International Luge Regulations. Salzburg Austria. 4. Fuss FK (2018) Slipstreaming in Gravity Powered Sports: Application to Racing Strategy in Ski Cross. Front Physiol 9:1032. 

Does the Body Mass Influence the Winning Time in Skeleton and Luge Competitions?

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1065&context=resec-isea

Does the Body Mass Influence the Winning Time in Skeleton and Luge Competitions?

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