PMID- 16799816
OWN - NLM
STAT- MEDLINE
DCOM- 20061120
LR  - 20200304
IS  - 1439-6319 (Print)
IS  - 1439-6319 (Linking)
VI  - 98
IP  - 1
DP  - 2006 Sep
TI  - Effect of altered pre-exercise carbohydrate availability on selection and 
      perception of effort during prolonged cycling.
PG  - 62-70
AB  - This study assessed the effect of altered carbohydrate (CHO) availability on 
      self-selected work rate during prolonged time-trial cycling. Eight 
      endurance-trained men undertook two experimental cycling time-trials after 
      glycogen-depleting exercise and 2 days of: (a) high (9.3 +/- 0 g CHO kg(-1) 
      day(-1)) (HC) and (b) low CHO intakes (0.6 +/- 0.1 g CHO kg(-1) day(-1)) (LC), 
      via a double-blinded crossover design. All feedback regarding performance was 
      removed during both exercise trials. Self-selected external power output was not 
      different during the first 2 h of exercise between experimental conditions (P > 
      0.05), despite reported sensations of increased tiredness before and during 
      exercise, significantly reduced whole body CHO oxidation (P < 0.05), plasma 
      lactate concentrations (P < 0.05) and earlier onset of fatigue during exercise in 
      LC versus HC. Perceived exertion was not different throughout exercise between 
      conditions (P > 0.05). Mean power output declined significantly in LC versus HC 
      (P < 0.05) after approximately 2 h of exercise, and was associated with 
      significant reductions in cadence, heart rate and plasma glucose concentration (P 
      < 0.05). These results demonstrate that when compared with time-trial cycling 
      performed after a HC diet, reduced CHO availability does not initially alter 
      self-selected work rate in endurance athletes who are deceived of their CHO 
      status prior to exercise. This finding suggests that reduced work rate during 
      exercise following lowered CHO intake may, in part, be a consequence of the 
      subject's awareness of dietary CHO restriction rather than solely a 
      physiologically mediated action. Further research is required to distinguish the 
      influence of circulating glucose and peripheral glycogen availability on pacing 
      strategy during prolonged exercise.
FAU - Johnson, N A
AU  - Johnson NA
AD  - The School of Exercise and Sport Science, The University of Sydney, Lidcombe, 
      Australia. n.johnson@fhs.usyd.edu.au
FAU - Stannard, S R
AU  - Stannard SR
FAU - Chapman, P G
AU  - Chapman PG
FAU - Thompson, M W
AU  - Thompson MW
LA  - eng
PT  - Controlled Clinical Trial
PT  - Journal Article
DEP - 20060624
PL  - Germany
TA  - Eur J Appl Physiol
JT  - European journal of applied physiology
JID - 100954790
RN  - 0 (Dietary Carbohydrates)
SB  - IM
MH  - Adaptation, Physiological/*physiology
MH  - Adult
MH  - Bicycling/*physiology
MH  - Biological Availability
MH  - Dietary Carbohydrates/*metabolism
MH  - Exercise Test
MH  - Humans
MH  - Male
MH  - Perception/physiology
MH  - Physical Endurance/*physiology
MH  - Physical Exertion/*physiology
EDAT- 2006/06/27 09:00
MHDA- 2006/12/09 09:00
CRDT- 2006/06/27 09:00
PHST- 2006/05/22 00:00 [accepted]
PHST- 2006/06/27 09:00 [pubmed]
PHST- 2006/12/09 09:00 [medline]
PHST- 2006/06/27 09:00 [entrez]
AID - 10.1007/s00421-006-0243-4 [doi]
PST - ppublish
SO  - Eur J Appl Physiol. 2006 Sep;98(1):62-70. doi: 10.1007/s00421-006-0243-4. Epub 
      2006 Jun 24.