Effects of Aerodynamic Drag and Drafting on Propulsive Force and Oxygen Consumption in Double Poling Cross-country Skiing

Abstract

Purpose To investigate the effects of aerodynamic drag and drafting on propulsive force (FPROP), drag area (CDA), oxygen cost (V˙O2), metabolic rate (E˙) and heart rate (HR) during roller skiing on a treadmill in a wind tunnel using the double poling technique. A secondary aim was to investigate the effects of wind versus no-wind test conditions on the same physiological parameters.

Methods 10 subjects of each gender participated in the experiments. One pair of skiers of the same gender roller skied simultaneously in line with the air flow; the distance between the skiers was ~2.05 m. Each pair was tested as follows: I) with wind, leading; II) with wind, drafting; III) without wind. The treadmill inclination was 0° throughout the tests. For the wind conditions, the air velocity was similar to the treadmill belt speed; men, 3 to 7 m · s-1; women 3 to 6 m · s-1.

Results Drafting resulted in significantly (P < 0.05) lower FPROP, CDA, V˙O2 and E˙, compared to leading, for both genders at racing speed but not at lower speeds, while HR was only affected for the male skiers at racing speed. The test without wind resulted in significantly lower FPROP, V˙O2 and E˙ at all tested speeds compared to the tests with wind present, while HR was lower only at higher speeds.

Conclusions At racing speed, but not at lower speeds, the positive effects of drafting behind a skier during double poling were obvious and resulted in a lower FPROP, CDA, V˙O2, E˙ and HR. Tests without wind present put even lower demands on the skiers’ physiology, which was also evident at lower speeds.