PMID- 9189727
OWN - NLM
STAT- MEDLINE
DCOM- 19970801
LR  - 20190831
IS  - 0301-5548 (Print)
IS  - 0301-5548 (Linking)
VI  - 75
IP  - 5
DP  - 1997
TI  - Effects of 3 days of carbohydrate supplementation on muscle glycogen content and 
      utilisation during a 1-h cycling performance.
PG  - 407-12
AB  - This study compared the effects of supplementing the normal diets of six trained 
      cyclists [maximal oxygen uptake (VO2max) 4.5 (0.36) l.min-1; values are mean 
      (SD)] with additional carbohydrate (CHO) on muscle glycogen utilisation during a 
      1-h cycle time-trial (TT). Using a randomised crossover design, subjects consumed 
      either their normal diet (NORM) for 3 days, which consisted of 426 (137) g.day-1 
      CHO [5.9 (1.4) g. kg-1 body mass (BM)], or additional CHO (SUPP) to increase 
      their intake to 661 (76) g.day-1 [9.3 (0.7) g. kg-1 BM]. The SUPP diet elevated 
      muscle glycogen content from 459 (83) to 565 (62) mmol.kg-1 dry weight (d.w.) (P 
      < 0.05). However, despite the increased pre-exercise muscle glycogen stores, 
      there was no difference in the distance cycled during the TT [40.41 (1.44) vs 
      40.18 (1.76) km for NORM and SUPP, respectively]. With NORM, muscle glycogen 
      declined from 459 (83) to 175 (64) mmol.kg-1 d.w., whereas with SUPP the 
      corresponding values were 565 (62) and 292 (113) mmol.kg-1 d.w. Accordingly, both 
      muscle glycogen utilisation [277 (64) vs 273 (114) mmol.kg-1 d.w.] and total CHO 
      oxidation [169 (20) vs 165 (30) g.h-1 for NORM and SUPP, respectively] were 
      similar. Neither were there any differences in plasma glucose or lactate 
      concentrations during the two experimental trials. Plasma glucose concentration 
      averaged 5.5 (0.5) and 5.6 (0.6) mmol.l-1, while plasma lactate concentration 
      averaged 4.4 (1.9) and 4.4 (2.3) mmol.l-1 for NORM and SUPP, respectively. The 
      results of this study show that when well-trained subjects increase the CHO 
      content of their diet for 3 days from 6 to 9 g.kg-1 BM there is only a modest 
      increase in muscle glycogen content. Since supplementary CHO did not improve TT 
      performance, we conclude that additional CHO provides no benefit to performance 
      for athletes who compete in intense, continuous events lasting 1 h. Furthermore, 
      the substantial muscle CHO reserves observed at the termination of exercise 
      indicate that whole-muscle glycogen depletion does not determine fatigue at this 
      exercise intensity and duration.
FAU - Hawley, J A
AU  - Hawley JA
AD  - Department of Physiology, University of Cape Town Medical School, South Africa.
FAU - Palmer, G S
AU  - Palmer GS
FAU - Noakes, T D
AU  - Noakes TD
LA  - eng
PT  - Clinical Trial
PT  - Journal Article
PT  - Randomized Controlled Trial
PT  - Research Support, Non-U.S. Gov't
PL  - Germany
TA  - Eur J Appl Physiol Occup Physiol
JT  - European journal of applied physiology and occupational physiology
JID - 0410266
RN  - 0 (Blood Glucose)
RN  - 0 (Dietary Carbohydrates)
RN  - 33X04XA5AT (Lactic Acid)
RN  - 9005-79-2 (Glycogen)
SB  - IM
MH  - Adult
MH  - Bicycling/*physiology
MH  - Blood Glucose/metabolism
MH  - Cross-Over Studies
MH  - Dietary Carbohydrates/*administration & dosage
MH  - Exercise/*physiology
MH  - Food, Fortified
MH  - Glycogen/*biosynthesis
MH  - Humans
MH  - Lactic Acid/blood/metabolism
MH  - Male
MH  - Muscle, Skeletal/*physiology
EDAT- 1997/01/01 00:00
MHDA- 1997/01/01 00:01
CRDT- 1997/01/01 00:00
PHST- 1997/01/01 00:00 [pubmed]
PHST- 1997/01/01 00:01 [medline]
PHST- 1997/01/01 00:00 [entrez]
AID - 10.1007/s004210050180 [doi]
PST - ppublish
SO  - Eur J Appl Physiol Occup Physiol. 1997;75(5):407-12. doi: 10.1007/s004210050180.