Physiological and metabolic responses to a hill walk.

Full Abstract

The physiological and metabolic demands of hill walking have not been studied systematically in the field despite the potentially deleterious physiological consequences of activity sustained over an entire day. On separate occasions, 13 subjects completed a self-paced hill walk over 12 km, consisting of a range of gradients and terrain typical of a mountainous walk. During the hill walk, continuous measurements of rectal (T(re)) and skin (T(sk)) temperatures and of respiratory gas exchange were made to calculate the total energy expenditure. Blood samples, for the analysis of metabolites and hormones, were taken before breakfast and lunch and immediately after the hill walk. During the first 5 km of the walk (100- to 902-m elevation), T(re) increased (36.9 +/- 0.2 to 38.5 +/- 0.4 degrees C) with a subsequent decrease in mean T(sk) from this time point. T(re) decreased by approximately 1.0 degrees C during a 30-min stop for lunch, and it continued to decrease a further 0.5 degrees C after walking recommenced. The total energy intake from both breakfast and lunch [5.6 +/- 0.7 (SE) MJ] was lower than the energy expended [14.5 +/- 0.5 (SE) MJ; P < 0.001] during the 12-km hill walk. Despite the difference in energy intake and expenditure, blood glucose concentration was maintained. The major source of energy was an enhanced fat oxidation, probably from adipose tissue lipolysis reflected in high plasma nonesterified fatty acid concentrations. The major observations were the varying thermoregulatory responses and the negative energy balance incurred during the hill walk. It is concluded that recreational hill walking can constitute a significant metabolic and thermoregulatory strain on participants.

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Author information

Author/s: Ainslie, P N (PN); Campbell, I T (IT); Frayn, K N (KN); Humphreys, S M (SM); Maclaren, D P M (DP); Reilly, T (T);

Affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool L3 2ET, United Kingdom. humpains(-atsign-)livjm.ac.uk

Journal and publication information

Publication Type: Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't

Journal: Journal of applied physiology (Bethesda, Md. : 1985) (J Appl Physiol), published in United States. (Language: eng)

Reference: 2002-Jan; vol 92 (issue 1) : pp 179-87

Dates: Created 2001/12/17; Completed 2002/04/10; Revised 2006/11/15;

PMID: 11744658, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adolescent
Adult
Affect - physiology
Body Temperature Regulation - physiology
Calorimetry, Indirect
Catecholamines - urine
Dietary Carbohydrates - metabolism
Dietary Fats - metabolism
Dietary Proteins - metabolism
Energy Metabolism - physiology
Exercise - physiology

Female
Heart Rate - physiology
Humans
Male
Oxygen Consumption - physiology
Physical Fitness - physiology
Psychomotor Performance - physiology
Pulmonary Gas Exchange - physiology
Stress, Mechanical
Temperature
Walking - physiology

Associated Chemicals: Catecholamines (0) ; Dietary Carbohydrates (0) ; Dietary Fats (0) ; Dietary Proteins (0)

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