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Optimal slopes and speeds in uphill ski mountaineering: a laboratory study

Abstract

Purpose

The purpose of this study was to estimate the energy cost of linear (EC) and vertical displacement (ECvert), mechanical efficiency and main stride parameters during simulated ski mountaineering at different speeds and gradients, to identify an optimal speed and gradient that maximizes performance.

Methods

12 subjects roller skied on a treadmill at three different inclines (10, 17 and 24 %) at three different speeds (approximately 70, 80 and 85 % of estimated peak heart rate). Energy expenditure was calculated by indirect calorimetry, while biomechanical parameters were measured with an inertial sensor-based system.

Results

At 10 % there was no significant change with speed in EC, ECvert and mechanical efficiency. At 17 and 24 % the fastest speed was significantly more economical. There was a significant effect of gradient on EC, ECvert and mechanical efficiency. The most economical gradient was the steepest one. There was a significant increase of stride frequency with speed. At steep gradients only, relative thrust phase duration decreased significantly, while stride length increased significantly with speed. There was a significant effect of gradient on stride length (decrease with steepness) and relative thrust phase duration (increase with steepness).

Conclusion

A combination of a decreased relative thrust phase duration with increased stride length and frequency decreases ECvert. To minimize the energy expenditure to reach the top of a mountain and to optimize performance, ski-mountaineers should choose a steep gradient (~24 %) and, provided they possess sufficient metabolic scope, combine it with a fast speed (~6 km h−1).

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Fig. 1

Abbreviations

ANOVA:

Analysis of variance

HRmax :

Maximum heart rate

HRmean :

Mean heart rate

HR:

Heart rate

\({\dot{V}}{\text O}_{2}\) :

Oxygen uptake

\({\dot{V}}{\text O}_{2max}\) :

Maximal oxygen uptake

References

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Acknowledgments

This work was supported by the Swiss federal office of sports.

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Authors and Affiliations

Authors

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Correspondence to Bengt Kayser.

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Conflict of interest

There are no competing interests.

Additional information

Communicated by Jean-René Lacour.

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Cite this article

Praz, C., Fasel, B., Vuistiner, P. et al. Optimal slopes and speeds in uphill ski mountaineering: a laboratory study. Eur J Appl Physiol 116, 1011–1019 (2016). https://doi.org/10.1007/s00421-016-3371-5

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  • DOI: https://doi.org/10.1007/s00421-016-3371-5

Keywords

  • Endurance
  • Skiing
  • Energy expenditure
  • Biomechanics