High-resolution friction measurements of cross-country ski bases on snow

Budde, Rick; Himes, Adam

doi:10.1007/s12283-017-0230-5

Cited by 18 publications

(15 citation statements)

References 11 publications

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“…This coefficient decreases progressively as the air temperature rises from below (around -10°C) to above zero (around + 5°C), irrespective of ski grinding and waxing. Budde and Himes estimated that when skiing on flat terrain, the time required to ski each kilometer increases by approximately 2 s for every 0.001 increase in the coefficient of friction ( Budde and Himes, 2017 ). Since the snow-ski friction coefficient was 0.014 lower on the second section here, skiing velocity would theoretically have been 19% or 28 s per kilometer faster on the second section, rising from 24 to 30 km⋅h -1 (assuming the same extent of fatigue).…”

Section: Discussionmentioning

confidence: 99%

“…where μ is the snow-ski friction coefficient, a deceleration, g gravitational acceleration and α the incline of the track ( Budde and Himes, 2017 ). We are aware that ski wax will be altered by prolonged skiing and that measurement of ski friction with skies that had been used for approximately 50 km would have provided a more realistic estimate of the snow-ski friction during the second session.…”

Section: Methodsmentioning

confidence: 99%

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Following a Long-Distance Classical Race the Whole-Body Kinematics of Double Poling by Elite Cross-Country Skiers Are Altered

Zoppirolli¹,

Bortolan

Stella

et al. 2018

Front. Physiol.

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Introduction: Although short-term (approximately 10-min) fatiguing DP has been reported not to alter the joint kinematics or displacement of the centre of mass (COM) of high-level skiers, we hypothesize that prolonged DP does change these kinematics, since muscular strength is impaired following endurance events lasting longer than 2 h.Methods: During the 58-km Marcialonga race in 2017, the fastest 15 male skiers were videofilmed (100 fps, FHD resolution in the sagittal plane) on two 20-m sections (inclines: 0.7 ± 0.1°) 48 km apart (i.e., 7 and 55 km from the start), approximating 50- km Olympic races. The cameras were positioned perpendicular to and about 40 m from the middle of each section and spatial dimensions adjusted for each individual track skied. Pole and joint kinematics, as well as displacement of the COM during two DP cycles were assessed.Results: The 10 skiers who fulfilled our inclusion criteria finished the race in 2 h 09 min 19 s ± 28 s. Displacements of the joints and COM were comparable to previous observations on skiers roller skiing on a flat treadmill at similar speeds in the laboratory. 55 km after the start, cycle velocity and length were lower (P < 0.001 and P = 0.002, respectively) and the angular range of elbow joint flexion during the initial part of the poling phase reduced, while shoulder angle was greater during the first 35% of the DP cycle (all P < 0.05). Moreover, the ankle angle was increased and forward displacement of the COM reduced during the first 80% of the cycle.Conclusion: Prolonged DP reduced the forward displacement of the COM and altered arm kinematics during the early poling phase. The inefficient utilization of COM observed after 2 h of competition together with potential impairment of the stretch-shortening of arm extensor muscles probably attenuated generation of poling force. To minimize these effects of fatigue, elite skiers should focus on maintaining optimal elbow and ankle kinematics and an effective forward lean during the propulsive phase of DP.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Following a Long-Distance Classical Race the Whole-Body Kinematics of Double Poling by Elite Cross-Country Skiers Are Altered

Zoppirolli¹,

Bortolan

Stella

et al. 2018

Front. Physiol.

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“…During the final ski preparation, various hand-held tools are frequently employed to create different microstructures. In recent years, considerable work and technological development have been devoted to precise characterization of friction during skiing ( Breitschädel et al, 2010 ; Swarén et al, 2014 ; Budde and Himes, 2017 ), with the aim of optimizing preparation and waxing. National teams now spend considerable money on highly specialized staff who prepares the skis and all major nations have designated waxing trailers where preparation can be optimized.…”

Section: Evolution Of Equipmentmentioning

confidence: 99%

“…For modern skis, the coefficient of friction, which exerts considerable impact on the total mechanical work required ( Pellegrini et al, 2014 ) or energy expended by a skier ( Saibene et al, 1989 ), can be as low as 0.005 on transformed wet snow and as high as 0.035 on cold, fresh snow ( Budde and Himes, 2017 ). During the 50-km freestyle event at the 1992 Winter Olympics, Street and Gregory (1994) observed a significant correlation ( r = -0.73) between finish time and glide speed.…”

Section: Evolution Of Equipmentmentioning

confidence: 99%

“…During the 50-km freestyle event at the 1992 Winter Olympics, Street and Gregory (1994) observed a significant correlation ( r = -0.73) between finish time and glide speed. Furthermore, the change in friction due to the texture of a wax or ski base is 0.001–0.010 ( Budde and Himes, 2017 ) and mathematical modeling estimated that lowering the friction coefficient by 0.001 would reduce race time for each kilometer by approximately 2 s ( Moxnes et al, 2014 ).…”

Section: Evolution Of Equipmentmentioning

confidence: 99%

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Developments in the Biomechanics and Equipment of Olympic Cross-Country Skiers

Pellegrini¹,

Stöggl

Holmberg

2018

Front. Physiol.

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Here, our aim was to describe the major changes in cross-country (XC) skiing in recent decades, as well as potential future developments. XC skiing has been an Olympic event since the very first Winter Games in Chamonix, France, in 1924. Over the past decades, considerable developments in skiing techniques and improvements in equipment and track preparation have increased skiing speed. In contrast to the numerous investigations on the physiological determinants of successful performance, key biomechanical factors have been less explored. Today’s XC skier must master a wide range of speeds, terrains, and race distances and formats (e.g., distance races with individual start, mass-start or pursuit; knock-out and team-sprint; relays), continuously adapting by alternating between various sub-techniques. Moreover, several of the new events in which skiers compete head-to-head favor technical and tactical flexibility and encourage high-speed techniques (including more rapid development of propulsive force and higher peak forces), as well as appropriate training. Moreover, the trends toward more extensive use of double poling and skiing without grip wax in classical races have given rise to regulations in connection with Olympic distances that appear to have preserved utilization of the traditional classical sub-techniques. In conclusion, although both XC equipment and biomechanics have developed significantly in recent decades, there is clearly room for further improvement. In this context as well, for analyzing performance and optimizing training, sensor technology has a potentially important role to play.

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A Novel Free-Gliding Ski Tribometer for Quantification of Ski–Snow Friction with High Precision

Sandberg,

Kalliorinne,

Hindér

et al. 2023

Tribol Lett

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The nature of snow and the ever-changing environment makes measuring friction on snow and ice challenging. Additionally, due to the low friction involved, the equipment used must exhibit high sensitivity. Previous investigations of ski–snow friction have ranged from small-scale model experiments performed in the laboratory to experiments with full-sized skis outdoors. However, few have been conducted under conditions similar to those encountered during actual skiing. Here, we present a novel sled tribometer which provides highly reproducible coefficient of friction (COF) values for full-sized skis gliding at relevant speeds (approximately 5.9 m/s) in a controlled indoor environment. The relative standard deviation (RSD) of the COF is as low as 0.5%. The continuous recording of velocity allows for innovative investigations into COF variations when skis are permitted to free-glide in a natural setting. Different methods of analysing the results are presented which shows that the precision is not a single number, but a function of the range of velocities over which the average COF is calculated. Graphical abstract

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High-resolution friction measurements of cross-country ski bases on snow

Cited by 18 publications

References 11 publications

Following a Long-Distance Classical Race the Whole-Body Kinematics of Double Poling by Elite Cross-Country Skiers Are Altered

Following a Long-Distance Classical Race the Whole-Body Kinematics of Double Poling by Elite Cross-Country Skiers Are Altered

Developments in the Biomechanics and Equipment of Olympic Cross-Country Skiers

A Novel Free-Gliding Ski Tribometer for Quantification of Ski–Snow Friction with High Precision

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