PMID- 9639351
OWN - NLM
STAT- MEDLINE
DCOM- 19980828
LR  - 20191024
IS  - 0958-0670 (Print)
IS  - 0958-0670 (Linking)
VI  - 83
IP  - 3
DP  - 1998 May
TI  - The effects of substrate and fluid provision on thermoregulatory, 
      cardiorespiratory and metabolic responses to prolonged exercise in a cold 
      environment in man.
PG  - 419-30
AB  - During prolonged exercise in a cold environment, fatigue is generally associated 
      with a depletion of endogenous glycogen stores. This has lead many authors to 
      hypothesize that the carbohydrate (CHO) content of fluids ingested in cool 
      environments should be high, yet this hypothesis has not been specifically 
      examined. In the present study, six healthy males cycled to exhaustion at 
      approximately 80% of their maximum oxygen consumption (V2O,max) with either no 
      drink (ND), a 15% CHO-electrolyte drink (15% CHO) or a 2% CHO electrolyte drink 
      (2% CHO). Dietary intake and exercise were replicated 2 days prior to each trial. 
      Mean (S.D.) ambient temperature was 10.0 (0.3) degrees C with a relative humidity 
      of 72 (2) % and an air velocity of approximately 0.7 m s(-1) on all trials. 
      Weighted mean skin temperature was calculated, and rectal temperature and heart 
      rate were recorded at rest, during exercise and at exhaustion. Venous samples 
      were drawn before and during exercise and at exhaustion for determination of 
      haemoglobin, haematocrit, blood metabolites and serum electrolytes and 
      osmolality. Expired air was collected for calculation of VO2 and respiratory 
      exchange ratio which were used to estimate rates of fuel oxidation. Ratings of 
      perceived exertion (RPE) were also obtained. Exercise capacity was not different 
      (P=0.49) between trials, with median (range) times to exhaustion of 90.6 
      (66.8-106.0), 97.7 (60.9-112.0) and 102.0 (77.1-170.7) min for the ND, 15% CHO 
      and 2% CHO trials, respectively. The 15% CHO drink significantly (P < 0.05) 
      elevated blood glucose concentration and total CHO oxidation compared with the ND 
      trial. The 2% CHO drink significantly (P < 0.05) reduced the estimated change in 
      plasma volume and resulted in a lower serum osmolality than the other two trials. 
      No differences were observed in any thermoregulatory or cardiorespiratory 
      responses between trials. These data suggest that maintenance of blood-borne 
      substrate and/or plasma volume does not influence exercise capacity in the cold, 
      as is commonly reported during this type and intensity of exercise in warmer 
      environments.
FAU - Galloway, S D
AU  - Galloway SD
AD  - Department of Environmental and Occupational Medicine, University Medical School, 
      Aberdeen, UK. s.d.r.galloway@strath.ac.uk
FAU - Maughan, R J
AU  - Maughan RJ
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - Exp Physiol
JT  - Experimental physiology
JID - 9002940
RN  - 0 (Electrolytes)
SB  - IM
MH  - Adult
MH  - Bicycling
MH  - Body Temperature Regulation/*physiology
MH  - *Cold Temperature
MH  - Electrolytes/blood/urine
MH  - Heart/*physiology
MH  - Humans
MH  - Male
MH  - Metabolism/*physiology
MH  - Oxygen Consumption/physiology
MH  - *Physical Exertion
MH  - Plasma Volume/physiology
MH  - Respiration/*physiology
EDAT- 1998/06/25 00:00
MHDA- 1998/06/25 00:01
CRDT- 1998/06/25 00:00
PHST- 1998/06/25 00:00 [pubmed]
PHST- 1998/06/25 00:01 [medline]
PHST- 1998/06/25 00:00 [entrez]
AID - 10.1113/expphysiol.1998.sp004125 [doi]
PST - ppublish
SO  - Exp Physiol. 1998 May;83(3):419-30. doi: 10.1113/expphysiol.1998.sp004125.