PMID- 14767872
OWN - NLM
STAT- MEDLINE
DCOM- 20040309
LR  - 20190725
IS  - 0026-0495 (Print)
IS  - 0026-0495 (Linking)
VI  - 53
IP  - 2
DP  - 2004 Feb
TI  - During exercise in the cold increased availability of plasma nonesterified fatty 
      acids does not affect the pattern of substrate oxidation.
PG  - 203-8
AB  - Exercise in the cold was investigated to establish if the relative contribution 
      of fat to energy expenditure is affected by the increased availability of 
      circulating nonesterified fatty acids (NEFA). Seven men after an overnight fast 
      cycled at approximately 70% of peak oxygen uptake for 60 minutes at an ambient 
      temperature of 0.0 degrees C +/- 0.1 degrees C. Fifteen minutes prior to exercise 
      and then throughout the exercise, subjects were infused with either heparin 
      (heparin) or saline (control). Immediately before exercise NEFA concentration 
      (control, 0.27 +/- 0.04 mmol. L(-1); heparin 1.09 +/- 0.13 mmol. l(-1)) was 
      significantly higher (P <.05) in the heparin trial. Pre-exercise concentration of 
      plasma triacylglycerol (TG), blood glycerol, glucose, oxygen consumption (VO(2)) 
      and respiratory exchange ratio (RER) were not significantly different between 
      heparin and control trials. During exercise, plasma NEFA and blood glycerol 
      concentrations were significantly higher (P <.05) in the heparin trial, and 
      levels of plasma TG and glucose were not different between trials. Over the 
      exercise period rectal temperature, mean skin temperature, VO(2), RER, and heart 
      rate (HR) were not different between the 2 trials. Gross energy expenditure of 
      cycling (control, 3.3 +/- 0.1 MJ; heparin 3.3 +/- 0.1 MJ), the oxidation rates of 
      fat (control, 0.67 +/- 0.05 g. min(-1); heparin, 0.71 +/- 0.06 g. min(-1)) and 
      carbohydrate (CHO) (control, 1.68 +/- 0.04 g.min(-1); heparin, 1.62 +/- 0.17 g. 
      min(-1)) and the proportion of energy derived from fat (control, 43 +/- 4%; 
      heparin trial, 44 +/- 9%) and CHO (control, 57 +/- 4%; heparin trial, 56 +/- 4%) 
      were not different between the 2 trials. These findings suggest that despite 
      increased availability of plasma NEFA, the pattern of substrate oxidation during 
      exercise in cold temperatures does not change. This implies that uncoupling 
      between the availability and oxidation of plasma NEFA may be a mechanism involved 
      in the reduced oxidation of fat seen during cold exposure. Further research is 
      needed on the utilization of intramuscular TG and circulating plasma TG-rich 
      lipoproteins in the cold.
FAU - Layden, Joseph D
AU  - Layden JD
AD  - Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 
      Glasgow, UK.
FAU - Malkova, Dalia
AU  - Malkova D
FAU - Nimmo, Myra A
AU  - Nimmo MA
LA  - eng
PT  - Clinical Trial
PT  - Journal Article
PL  - United States
TA  - Metabolism
JT  - Metabolism: clinical and experimental
JID - 0375267
RN  - 0 (Blood Glucose)
RN  - 0 (Fats)
RN  - 0 (Fatty Acids, Nonesterified)
RN  - 0 (Hemoglobins)
RN  - 0 (Triglycerides)
RN  - PDC6A3C0OX (Glycerol)
SB  - IM
MH  - Adult
MH  - Algorithms
MH  - Anaerobic Threshold/physiology
MH  - Blood Gas Analysis
MH  - Blood Glucose/metabolism
MH  - Body Temperature/physiology
MH  - Carbohydrate Metabolism
MH  - *Cold Temperature
MH  - Exercise/*physiology
MH  - Exercise Test
MH  - Fats/metabolism
MH  - Fatty Acids, Nonesterified/*blood
MH  - Glycerol/blood
MH  - Hematocrit
MH  - Hemoglobins/metabolism
MH  - Humans
MH  - Kinetics
MH  - Male
MH  - Muscle, Skeletal/physiology
MH  - Oxidation-Reduction
MH  - Triglycerides/blood
EDAT- 2004/02/10 05:00
MHDA- 2004/03/10 05:00
CRDT- 2004/02/10 05:00
PHST- 2004/02/10 05:00 [pubmed]
PHST- 2004/03/10 05:00 [medline]
PHST- 2004/02/10 05:00 [entrez]
AID - S0026049503004608 [pii]
AID - 10.1016/j.metabol.2003.09.018 [doi]
PST - ppublish
SO  - Metabolism. 2004 Feb;53(2):203-8. doi: 10.1016/j.metabol.2003.09.018.