Gait models and mechanical energy in three cross-country skiing techniques

Abstract

Fluctuations in mechanical energy of the body center of mass (COM) have been widely analyzed when investigating different gaits in human and animal locomotion. We applied this approach to estimate the mechanical work in cross-country skiing and to identify the fundamental mechanisms of this particular form of locomotion. We acquired movements of body segments, skis, poles and plantar pressures for eight skiers while they roller skied on a treadmill at 14 km h −1 and a 2 deg slope using three different techniques (diagonal stride, DS; double poling, DP; double poling with kick, DK). The work associated with kinetic energy (KE) changes of COM was not different between techniques; the work against gravity associated with potential energy (PE) changes was higher for DP than for DK and was lowest for DS. Mechanical work against the external environment was 0.87 J m −1 kg −1 for DS, 0.70 J m −1 kg −1 for DP and 0.79 J m −1 kg −1 for DK. The work done to overcome frictional forces, which is negligible in walking and running, was 17.8%, 32.3% and 24.8% of external mechanical work for DS, DP and DK, respectively. The pendulum-like recovery (R%) between PE and KE was ~45%, 26% and ~9% for DP, DK and DS, respectively, but energy losses by friction are not accounted for in this computation. The pattern of fluctuations of PE and KE indicates that DS can be described as a 'grounded running', where aerial phases are substituted by ski gliding phases, DP can be described as a pendular gait, whereas DK is a combination of both.

Effects of Caffeine on Time Trial Performance and Associated Physiological Responses: A Meta-Analysis

“…where d is the distance of the time trial and t is completion time. The mean power outputs for time trial tasks performed on skiing ergometers were converted using the energy cost of 0.70 J/(m$kg) reported by Pellegrini et al 56 for the double-poling technique. The data from Berglund and Hemmingson 30 were subjected to the same conversion.…”

Exhaustive Classification and Review of Techniques and Research Program for Techniques for Skate Skiing, Classical Skiing, and Ski Mountaineering

“…Style changes in cross country skiing have to the author's knowledge not been analyzed. However, technique changes within classical skiing have been analyzed, as described by Pellegrini et al [5] and Pellegrini et al [36]. While style transitions in cross-country skiing are probably not as challenging as in triathlon, the extra energy costs and time lost while changing technique versus the unloading and variations of muscle load is interesting both from a physiological, biomechanical and motor control perspective and should be further investigated.…”

Embedded inertial measurement unit reveals pole lean angle for cross-country skiing

“…This interest spans the entire range of skiing events from sprint courses to long-distance marathons where DP remains prevalent [2]. Prior studies highlight the overall importance and influence of the poling forces arising from DP [1,[3][4][5][6][7][8][9][10][11][12].…”

“…The ability to measure these three factors while actively skiing outdoors on a course remains a clear challenge. These studies [1,[3][4][5][6][7][8][9][10][11][12] have measured these factors only in laboratory settings or in highly controlled conditions that preclude characterizing propulsion on outdoor courses.…”