HIGH RESISTANCE ROLLER SKIS INDUCE GREATER UPPER BODY DEMANDS THAN LOW RESISTANCE ROLLER SKIS IN SKI SKATING 44

Abstract

The upper body generates a large proportion of the propulsive forces during ski skating. While cross-country skiers have a wide variety of roller skis from which to choose for dry-land training, few studies have examined the effects of rolling resistance on upper body demands. The purpose of this study was to examine the effects of roller ski rolling resistance on poling forces with the V2-alternate skate technique. Nine male cross-country ski racers with mean (±1SD) age of 33±7 years completed the study. Each subject roller skied for 4 minutes at 3 submaximal paced speeds on a flat asphalt roadway with high (HiR) and low (LowR) resistance roller skis (V2 820 and 850, Jenex, Inc.). The coefficient of rolling resistance for HiR was double that of LowR. Oxygen uptake (VO2), heart rate (HR) and axial forces through a pole were measured during the last minute of each bout of exercise, and rating of perceived exertion (RPE) was requested immediately after each bout. Pole force information obtained from a piezoelectric force transducer was averaged over 5 consecutive cycles. Two-way repeated measures ANOVA revealed that VO2, average force (AF) and average force across the entire cycle (ACF) were higher (31%, 26% and 38%, respectively; p<0.01) at each speed with HiR. Poling time was similar, while cycle rate and duty cycle were higher(p<0.05) at each speed with HiR. At a given RPE and HR, VO2 was not significantly different, while ACF was higher (p<0.01) with HiR. At a given VO2, ACF was higher (p<0.01) with HiR, whereas AF was similar between roller skis. We conclude that (1) differences of this magnitude in rolling resistance produce measurable differences in VO2, poling force and upper body recovery time for V2-alternate skating on flat terrain, and (2) the upper body demands for a given VO2, HR or RPE are greater with high resistance roller skis compared with low resistance roller skis.