PMID- 20535618
OWN - NLM
STAT- MEDLINE
DCOM- 20110214
LR  - 20211020
IS  - 1439-6327 (Electronic)
IS  - 1439-6319 (Linking)
VI  - 110
IP  - 3
DP  - 2010 Oct
TI  - Fuel oxidation in relation to walking speed: influence of gradient and external 
      load.
PG  - 515-21
LID - 10.1007/s00421-010-1523-6 [doi]
AB  - People intuitively walk at a speed that minimizes energy cost per meter. 
      Therefore, the selective advantages of energetic efficiency are thought to drive 
      individuals' preferred walking speed (PWS). This presumption disregards fuel 
      partitioning, which may, in fact, be significant due to the disparate sizes of 
      the carbohydrate (CHO) and fat reservoirs, coupled with the necessity of CHO for 
      high intensity exercise. Potentially, PWS may reflect CHO conservation more than 
      energetic efficiency per se. This study was designed to determine if PWS over a 
      variety of conditions conforms to the CHO sparing hypothesis. Six subjects walked 
      on a treadmill at five speeds: their PWS and speeds 0.45 and 0.22 m/s below and 
      above PWS, under loads of 0, 10, and 20% of body weight, as well as at grades of 
      -6.25, 0 and +6.25%. Oxygen consumption, carbon dioxide production and 
      respiratory exchange ratio were measured over each 10 min bout to calculate total 
      energy, CHO and fat usage. The subjects' mean (+/-SD) unloaded, level PWS was 1.32 
      +/- 0.11 m/s. PWS was reduced by the 20% load and uphill grade, but not affected by 
      the 10% load or downhill grade. Carbohydrate provided >/=50% of required energy in 
      all conditions. The CHO oxidation rate was related to speed such that the gain 
      was greater at speeds above than below the PWS; however, differences in CHO 
      oxidation between conditions did not correspond to differences in PWS. We 
      conclude that CHO sparing is not the primary determinant of PWS during externally 
      loaded or grade walking.
FAU - Entin, Pauline L
AU  - Entin PL
AD  - SA Rasmussen Exercise Physiology Laboratory, Department of Biological Sciences, 
      Northern Arizona University, Flagstaff, AZ 86011, USA. Pauline.entin@nau.edu
FAU - Gest, Colleen
AU  - Gest C
FAU - Trancik, Susan
AU  - Trancik S
FAU - Richard Coast, J
AU  - Richard Coast J
LA  - eng
PT  - Clinical Trial
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20100610
PL  - Germany
TA  - Eur J Appl Physiol
JT  - European journal of applied physiology
JID - 100954790
SB  - IM
MH  - Adolescent
MH  - Adult
MH  - Carbohydrate Metabolism/physiology
MH  - Energy Metabolism/*physiology
MH  - Exercise Test
MH  - Female
MH  - Humans
MH  - Lipid Metabolism/physiology
MH  - Male
MH  - Oxidation-Reduction
MH  - Oxygen Consumption/physiology
MH  - Pulmonary Gas Exchange/physiology
MH  - Walking/*physiology
MH  - Weight-Bearing/*physiology
MH  - Young Adult
EDAT- 2010/06/11 06:00
MHDA- 2011/02/15 06:00
CRDT- 2010/06/11 06:00
PHST- 2010/05/21 00:00 [accepted]
PHST- 2010/06/11 06:00 [entrez]
PHST- 2010/06/11 06:00 [pubmed]
PHST- 2011/02/15 06:00 [medline]
AID - 10.1007/s00421-010-1523-6 [doi]
PST - ppublish
SO  - Eur J Appl Physiol. 2010 Oct;110(3):515-21. doi: 10.1007/s00421-010-1523-6. Epub 
      2010 Jun 10.