Differences in Cardiorespiratory Responses in Winter Mountaineering According to the Pathway Snow Conditions

Abstract

Locomotion during ascent requires higher energy consumption than on flat terrain. Locomotion efficiency decreases in snowy terrain, with changes in the biomechanical pattern of walking. This study aims to evaluate differences in both cardiorespiratory responses and energy expenditure between locomotion over snowy terrain with an established footstep pathway (FP) and fresh snow (FS) that has not previously been compacted. Fifteen volunteers with experience in mountain activities at a competition level and a regular training schedule of up to 10 hours a week participated in the study. Estimated maximal theoretical oxygen consumption showed a mild increase (2.6%, 95% confidence interval: 0.9%-4.5%, t = 3.2, p = 0.005) when subjects followed the FP compared with FS. More time was necessary to complete locomotion in FS (256 ± 30 seconds) than FP (225 ± 29 seconds; p = 0.01). Uphill walking velocity increased by 0.43 ± 0.11 km/h (t = 4.2, p = 0.01) in FP compared with FS; and the FS respiratory rate was higher (by 2.3 ± 2.4 beats/min, t = 4.0, p = 0.001). For a same itinerary, locomotion in snow that has not been compacted before requires more time and represents a higher energetic cost, either at maximal or submaximal intensities. This should be considered in scheduling mountain ascents as part of the safety strategies. Climbing on virgin snow impedes developing maximal aerobic power, so athletes must regard the value of strength work of lower limbs to improve performance. Indirect calculation of maximal oxygen consumption based on time to complete locomotion in FP can have practical application as a field test.