Intensity pacing strategy and downhill strategy during a cross country ski race

INTRODUCTION During a cross country ski race the intensity pacing strategy could be affected by different variables. It’s not easy to choose the winner strategy. In a previous analysis we found no correlation between the mean heart rate (HR) during the race and the time of the race (RT). In a downhill, the HR normally decreases until the beginning of next flat or uphill. The HR-trend during downhill can be influenced by the payment of oxygen debt and different downhill strategy (Mognoni et al., 2001). The aim of this study was to investigate which intensity pacing strategy would give the best race time during a cross country ski race. METHODS During a 10 km interval start skating race, HR of 9 male cross country skiers (Category U-23) was recorded by Polar RS400® (Hz.5sec). We found that all the racers had a clear decrease in HR at about 7 km, in correspondence with a long downhill. We considered the percentage of HR max given by the subjects (%HRmax) pre and post the downhill (%∆HR=%HRpre−%HRpost). In order to study the influence of downhill strategies on the RT, we calculated the correlation index between %∆HR and RT for all the skiers. As indicator of intensity pacing strategy, we used the angular coefficient of the linear regression for all the HR profiles. HR data were analyzed by Polar Pro Trainer® and Microsoft Excel 2003®. RESULTS From angular coefficients, we noticed that all the subjects incremented their HR from the start to the end. There were no correlation between the angular coefficient and RT (R2=0.013), and between %∆HR and the RT for all the skiers (R2=0.005), showing that the capacity of recovery during the downhill did not influence RT. The decrease in HR changes from subject to subject. DISCUSSION The increment of HR from the start to the end, as the angular coefficients show, has not a linear relationship with RT. This is in opposition with which was found by Lima-Silva (2010) in 10-km running race. The decrease in HR during the downhill, changing for each subject strategy, did not influence RT. The skiers could push faster to increase speed or let the ski flow to recover (Bilodeau et al., 1991). %∆HR could be influenced by individual technique, ski wax, athletic condition and the kind of work during the downhill. The final part of the race reflects higher intensity as compared to the initial, even if each skier chose his preferred strategy both during the whole race and the downhill. We hypothesise that the skiers used different pacing and downhill strategies during this downhill, a new study is prepared to focus upon this. REFERENCES Bilodeau B. et al. (1991). Int. J. Sports Med. 12:71-76. Lima-Silva A.E. et al. (2010). Eur. J. Appl. Physiol. 108:1045-1053. Mognoni P. et al. (2001). Eur. J. Appl. Physiol. 85:62-27.