Differences in cardiorespiratory responses in winter mountaineering according to the pathway snow conditions

Abstract

Locomotion during ascent requires higher energetic consumption than in flat terrain. Efficiency in locomotion decreases in snowy terrain, presumably because of the changes in the biomechanical pattern of walking. This study aims to observe differences in cardiorespiratory responses and energetic expenditure between locomotion in a snowy terrain with an already fixed footstep pathway (FP) and in fresh virgin snow (FS) that has not been previously compacted. 15 volunteers participated in the study, all of them with experience in mountain activities at a competition level, with a regular training regime up to 10 hours a week. Estimated maximal theoretical oxygen consumption showed a mild increase (2,6% CI 95%: 0.9-4.5%, t=3.2, p=0.005) when subjects progressed in FP. Time necessary to complete FS (4 min and 15 sec ± 30 sec) itinerary was longer than for FP (3 min 45 sec ± 29 sec). Uphill walking velocity improved in 0.43 ± 0.11 Km·h-1 (t=4.2 p=0,01) when progressing in CT. Respiratory rate was higher for FS (2.3 ± 2.4 b·min-1, 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.