The optimum gradient of mountain paths.
Minetti, Alberto E.
Istituto Tecnologie Biomediche Avanzate, Reparto Fisiologia del
Lavoro Muscolare, C.N.R. Via Amp[grave]ere 56 - 20131 Milano,
Italy
APStracts 2:0291A, 1995.
By combining the experimental results from R. Margaria (1938)
regarding the metabolic cost of gradient locomotion together with
recent insights on gait biomechanics, a prediction about the most
economical gradient of mountain paths (about 25%) is obtained and
interpreted. The pendulum-like mechanism of walking produces a waste
of mechanical work against gravity within the gradient range of up to
15% (the overall efficiency is dominated by the low 'transmission'
efficiency), while for steeper values only the muscular efficiency is
responsible for the (slight) metabolic change (per meter of vertical
displacement) with respect to gradient. The speeds at the optimum
gradient turned out to be about 0.65 m/s (+0.16 m/s vertical) and
1.50 m/s (-0.36 m/s vertical), for uphill and downhill walking
respectively, and the ascensional energy expenditure was 0.4 and 2.0
mlO2 per kg of body mass and per vertical meter climbed or descended.
When the metabolic power becomes a burden, as in high altitude
mountaineering, the optimum gradient should be reduced. A sample of
of real mountain path gradients, experimentally measured, mimic the
obtained predictions.
Received 20 March 1995; accepted in final form 20 June 1995.
APS Manuscript Number A302-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.