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Physiological and metabolic responses to a hill walk
P N Ainslie1, I T Campbell, K N Frayn
1Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool L3 2ET, United Kingdom. humpains@livjm.ac.uk
Journal of Applied Physiology (Bethesda, Md. : 1985)
|December 18, 2001
Summary
Hill walking creates a significant energy deficit, with expenditure far exceeding intake. Participants experienced varying thermoregulation and relied on fat oxidation for energy.
Area of Science:
- Exercise Physiology
- Environmental Physiology
- Human Metabolism
Background:
- Physiological and metabolic demands of sustained hill walking are not well-documented.
- Recreational hill walking can pose significant physiological challenges.
Purpose of the Study:
- To systematically investigate the physiological and metabolic responses to a typical 12-km hill walk.
- To assess energy expenditure, thermoregulation, and metabolic changes during field-based hill walking.
Main Methods:
- 13 subjects undertook a 12-km self-paced hill walk with varying gradients and terrain.
- Continuous monitoring of core (rectal) and skin temperatures, and respiratory gas exchange.
- Analysis of blood metabolites and hormones pre- and post-exercise.
Main Results:
- Core body temperature initially rose, then fell, particularly during rest periods.
- Energy expenditure (14.5 MJ) significantly exceeded energy intake (5.6 MJ), creating a negative energy balance.
- Blood glucose was maintained, with enhanced fat oxidation as the primary energy source, indicated by elevated nonesterified fatty acids.
Conclusions:
- Hill walking induces significant metabolic and thermoregulatory strain.
- Participants enter a notable negative energy balance during prolonged hill walking.
- Enhanced fat mobilization is crucial for sustaining energy demands during this activity.