PMID- 11896023
OWN - NLM
STAT- MEDLINE
DCOM- 20020708
LR  - 20220317
IS  - 8750-7587 (Print)
IS  - 0161-7567 (Linking)
VI  - 92
IP  - 4
DP  - 2002 Apr
TI  - Heat stress increases muscle glycogen use but reduces the oxidation of ingested 
      carbohydrates during exercise.
PG  - 1562-72
AB  - The aim of the present study was to test the hypothesis that the oxidation rate 
      of ingested carbohydrate (CHO) is impaired during exercise in the heat compared 
      with a cool environment. Nine trained cyclists (maximal oxygen consumption 65 +/- 
      1 ml x kg body wt(-1) x min(-1)) exercised on two different occasions for 90 min 
      at 55% maximum power ouptput at an ambient temperature of either 16.4 +/- 0.2 
      degrees C (cool trial) or 35.4 +/- 0.1 degrees C (heat trial). Subjects received 
      8% glucose solutions that were enriched with [U-13C]glucose for measurements of 
      exogenous glucose, plasma glucose, liver-derived glucose and muscle glycogen 
      oxidation. Exogenous glucose oxidation during the final 30 min of exercise was 
      significantly (P < 0.05) lower in the heat compared with the cool trial (0.76 +/- 
      0.06 vs. 0.84 +/- 0.05 g/min). Muscle glycogen oxidation during the final 30 min 
      of exercise was increased by 25% in the heat (2.07 +/- 0.16 vs. 1.66 +/- 0.09 
      g/min; P < 0.05), and liver-derived glucose oxidation was not different. There 
      was a trend toward a higher total CHO oxidation and a lower plasma glucose 
      oxidation in the heat although this did not reach statistical significance (P = 
      0.087 and P = 0.082, respectively). These results demonstrate that the oxidation 
      rate of ingested CHO is reduced and muscle glycogen utilization is increased 
      during exercise in the heat compared with a cool environment.
FAU - Jentjens, Roy L P G
AU  - Jentjens RL
AD  - Human Performance Laboratory, School of Sport and Exercise Sciences, University 
      of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
FAU - Wagenmakers, Anton J M
AU  - Wagenmakers AJ
FAU - Jeukendrup, Asker E
AU  - Jeukendrup AE
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Appl Physiol (1985)
JT  - Journal of applied physiology (Bethesda, Md. : 1985)
JID - 8502536
RN  - 0 (Blood Glucose)
RN  - 0 (Carbon Isotopes)
RN  - 0 (Dietary Carbohydrates)
RN  - 33X04XA5AT (Lactic Acid)
RN  - 9005-79-2 (Glycogen)
RN  - IY9XDZ35W2 (Glucose)
SB  - IM
MH  - Adult
MH  - Bicycling
MH  - Blood Glucose/metabolism
MH  - Body Mass Index
MH  - Carbon Isotopes
MH  - Dietary Carbohydrates/*pharmacokinetics
MH  - Digestive System/physiopathology
MH  - Glucose/pharmacokinetics
MH  - Glycogen/*metabolism
MH  - Heart Rate
MH  - Heat Stress Disorders/*metabolism
MH  - Humans
MH  - Lactic Acid/metabolism
MH  - Male
MH  - Muscle, Skeletal/*metabolism
MH  - Oxidation-Reduction
MH  - Perception
MH  - Physical Exertion/*physiology
MH  - Plasma Volume
EDAT- 2002/03/16 10:00
MHDA- 2002/07/09 10:01
CRDT- 2002/03/16 10:00
PHST- 2002/03/16 10:00 [pubmed]
PHST- 2002/07/09 10:01 [medline]
PHST- 2002/03/16 10:00 [entrez]
AID - 10.1152/japplphysiol.00482.2001 [doi]
PST - ppublish
SO  - J Appl Physiol (1985). 2002 Apr;92(4):1562-72. doi: 
      10.1152/japplphysiol.00482.2001.