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Purpose: This study aimed to investigate the effects of aerodynamic drag and drafting on propulsive force (F PROP), drag area (C D A), 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: Ten 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; and 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: 3 to 7 m·s−1 for men and 3 to 6 m·s−1 for women. Results: Drafting resulted in significantly (P < 0.05) lower F PROP, C D A , V˙O2, and E ˙, compared with leading, for both genders at racing speed but not at lower speeds, whereas HR was only affected for the male skiers at racing speed. The test without wind resulted in significantly lower F PROP, V˙O2, and E ˙ at all tested speeds compared with the tests with wind present, whereas 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 F PROP, C D A , V˙O2, E ˙, and HR. Tests without wind present put even lower demands on the skiers' physiology, which was also evident at lower speeds. [ABSTRACT FROM AUTHOR]

Abstract: Roller skis are used by cross-country skiers, biathletes and ski-orienteers for their snow-free training and in roller ski competitions. Additionally, much of the current sports research into the physiology and biomechanics of cross- country skiing is conducted indoors on treadmills using roller skis. For elite athletes, the differences in performance are quite small, thus emphasising the importance of knowing the roller skis’ rolling resistance coefficient, especially in connection to research and roller ski competitions. The purpose of this study was to develop a roller ski rolling resistance measurement system (P-RRMS) that is portable and therefore useful in different contexts and locations. The P-RRMS was designed as a small treadmill, equipped with roller ski stabilizing lateral supports and a screwed bar for applying different vertical loads on the roller ski. The design uses only one force sensor, with possible measurements of three directions of force and torque around three axes. The weight of the P-RRMS is 100kg and it is equipped with wheels to facilitate transportation. [Copyright &y& Elsevier]

The article discusses research which was conducted to compare skiing economy and efficiency in recreational and elite cross-country skiers. Researchers evaluated skiers who performed roller skiing on a treadmill. They found that the elite cross country skiers had better skiing economy and higher gross efficiency than the recreational skiers and that the senior elite had better economy and higher efficiency than their junior counterparts.

A program for numerical simulation of a whole ski race, from start to finish, is developed in MATLAB. The track is modelled by a set of cubical splines in two dimensions and can be used to simulate a track in a closed loop or with the start and finish at different locations. The forces considered in the simulations are gravitational force, normal force between snow and skis, drag force from the wind, frictional force between snow and ski and driving force from the skier. The differential equations of motion are solved from start to finish with the Runge-Kutta method. Different wind situations during the race can be modelled, as well as different glide conditions on different parts of the track. It is also possible to vary the available power during the race. The simulation program's output is the total time of the race, together with the forces and speed during different parts of the race and intermediate times at selected points. Some preliminary simulations are also presented. [ABSTRACT FROM AUTHOR]