PMID- 11039653
OWN - NLM
STAT- MEDLINE
DCOM- 20010208
LR  - 20190831
IS  - 0195-9131 (Print)
IS  - 0195-9131 (Linking)
VI  - 32
IP  - 10
DP  - 2000 Oct
TI  - Effect of fluid intake volume on 2-h running performances in a 25 degrees C 
      environment.
PG  - 1783-9
AB  - PURPOSE: In this study, we examined the effects of greater than ad libitum rates 
      of fluid intake on 2-h running performances. METHODS: Eight male distance runners 
      performed three runs on a treadmill at 65% of peak oxygen uptake (VO2peak) for 90 
      min and then ran "as far as possible" in 30 min in an air temperature of 25 
      degrees C, a relative humidity of 55% and a wind speed of 13-15 km x h(-1). 
      During the runs, the subjects drank a 6.9% carbohydrate (CHO)-electrolyte 
      solution either ad libitum or in set volumes of 150 or 350 mL x 70 kg(-1) body 
      mass (approximately 130 or 300 mL) every 15-20 min. RESULTS: Higher 
      (approximately 0.9 vs 0.4 L x h(-1)) rates of fluid intake in the 350 mL x 70 
      kg(-1) trial than in the other trials had minimal effects on the subjects' urine 
      production (approximately 0.1 L x h(-1)), sweat rates (approximately 1.2 L x 
      h(-1)), declines in plasma volume (approximately 8%), and rises in serum 
      osmolality (approximately 5 mosmol x L(-1)) and Na+ concentrations (approximately 
      7 mEq x L(-1)). A greater (approximately 1.0 vs 0.5 g x min(-1)) rate of CHO 
      ingestion in the 350 mL x 70 kg(-1) trial than in the other trials also did not 
      affect plasma concentrations of glucose (> or = 5 mmol x L(-1)) and lactate 
      (approximately 3 mmol x L(-1)) during the performance runs. In all three 
      performance runs, increases in running speeds from approximately 14 to 15-16 km x 
      h(-1) and rises in exercise intensities from approximately 65% to 75% of VO2peak 
      elevated plasma lactate concentrations from approximately 1.5 to 3 mmol x L(-1) 
      and accelerated CHO oxidation from approximately 13 to 15 mmol x min(-1). The 
      only effect of the additional intake of approximately 1.0 L of fluid in the 350 
      mL x 70 kg(-1) trial was to produce such severe gastrointestinal discomfort that 
      two of the eight subjects failed to complete their performance runs. CONCLUSION: 
      Greater rates of fluid ingestion had no measurable effects on plasma volume and 
      osmolality and did not improve 2-h running performances in a 25 degrees C 
      environment.
FAU - Daries, H N
AU  - Daries HN
AD  - University of Cape Town Bioenergetics of Exercise Research Unit, Sports Science 
      Institute of South Africa, Newlands.
FAU - Noakes, T D
AU  - Noakes TD
FAU - Dennis, S C
AU  - Dennis SC
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Med Sci Sports Exerc
JT  - Medicine and science in sports and exercise
JID - 8005433
RN  - 0 (Blood Glucose)
RN  - 0 (Rehydration Solutions)
RN  - 33X04XA5AT (Lactic Acid)
RN  - 9NEZ333N27 (Sodium)
RN  - RWP5GA015D (Potassium)
SB  - IM
MH  - Abdominal Pain/etiology
MH  - Adult
MH  - Blood Glucose/metabolism
MH  - *Drinking
MH  - Humans
MH  - Lactic Acid/blood
MH  - Male
MH  - Plasma Volume
MH  - Potassium/blood
MH  - Rehydration Solutions/adverse effects/*therapeutic use
MH  - Running/*physiology
MH  - Sodium/blood
MH  - Temperature
MH  - Time Factors
MH  - Water-Electrolyte Balance/physiology
EDAT- 2000/10/20 11:00
MHDA- 2001/03/03 10:01
CRDT- 2000/10/20 11:00
PHST- 2000/10/20 11:00 [pubmed]
PHST- 2001/03/03 10:01 [medline]
PHST- 2000/10/20 11:00 [entrez]
AID - 10.1097/00005768-200010000-00019 [doi]
PST - ppublish
SO  - Med Sci Sports Exerc. 2000 Oct;32(10):1783-9. doi: 
      10.1097/00005768-200010000-00019.