Document Detail


Himalayan porter's specialization: metabolic power, economy, efficiency and skill.
MedLine Citation:
PMID:  17015318     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Carrying heavy loads in the Himalayan region is a real challenge. Porters face extreme ranges in terrain condition, path steepness, altitude hypoxia and climate for 6-8h a day, many months a year, since they were boys. It has been previously shown that, when carrying loads on level terrain, porters' metabolic economy is higher than in Caucasians but the reasons are still unknown. We monitored Nepalese porters both during 90 km trekking in Khumbu Valley and at two different altitudes (3490 and 5050 m above sea-level), where they were compared to Caucasian mountaineers during (22%) gradient walking. Both subject groups carried a load of up to 90% body mass. The remarkably higher performance of porters during uphill locomotion (+60% in speed, +39% mechanical power) is only partly explained by the lower cost of loaded walking (-20%), being also the result of a better cardio-circulatory adaptation to altitude, which generates a higher mass-specific metabolic power (+30%). Consequently, Nepalese porters show higher efficiency, both during uphill and downhill loaded walking. Their higher economy on steep paths cannot be ascribed to a better exchange between potential and kinetic energy, as in our experiments the body centre of mass travelled monotonically uphill (or downhill). A different oscillation pattern of the loaded head-trunk segment, together with the analysis of the different components of the mechanical work during load carrying, suggests that achieved motor skills in balancing the loaded body segment above the hip could play a role in determining the better economy of porters.
Authors:
Alberto E Minetti; Federico Formenti; Luca P Ardigò
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Proceedings. Biological sciences / The Royal Society     Volume:  273     ISSN:  0962-8452     ISO Abbreviation:  Proc. Biol. Sci.     Publication Date:  2006 Nov 
Date Detail:
Created Date:  2006-12-14     Completed Date:  2007-02-01     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  101245157     Medline TA:  Proc Biol Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  2791-7     Citation Subset:  IM    
Affiliation:
Faculty of Medicine, Institute of Human Physiology, University of Milan, Milan 20133, Italy. alberto.minetti@unimi.it
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MeSH Terms
Descriptor/Qualifier:
Adult
Altitude
Energy Metabolism*
Humans
Lifting*
Male
Nepal
Oxygen Consumption
Physical Endurance
Physical Exertion*
Walking*
Weight-Bearing*
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