PMID- 16188909
OWN - NLM
STAT- MEDLINE
DCOM- 20060222
LR  - 20081121
IS  - 0193-1849 (Print)
IS  - 0193-1849 (Linking)
VI  - 290
IP  - 2
DP  - 2006 Feb
TI  - Decreased PDH activation and glycogenolysis during exercise following fat 
      adaptation with carbohydrate restoration.
PG  - E380-8
AB  - Five days of a high-fat diet while training, followed by 1 day of carbohydrate 
      (CHO) restoration, increases rates of whole body fat oxidation and decreases CHO 
      oxidation during aerobic cycling. The mechanisms responsible for these shifts in 
      fuel oxidation are unknown but involve up- and downregulation of key regulatory 
      enzymes in the pathways of skeletal muscle fat and CHO metabolism, respectively. 
      This study measured muscle PDH and HSL activities before and after 20 min of 
      cycling at 70% VO2peak and 1 min of sprinting at 150% peak power output (PPO). 
      Estimations of muscle glycogenolysis were made during the initial minute of 
      exercise at 70% VO2peak and during the 1-min sprint. Seven male cyclists 
      undertook this exercise protocol on two occasions. For 5 days, subjects consumed 
      in random order either a high-CHO (HCHO) diet (10.3 g x kg(-1) x day(-1) CHO, or 
      approximately 70% of total energy intake) or an isoenergetic high-fat (FAT-adapt) 
      diet (4.6 g x kg(-1) x day(-1) FAT, or 67% of total energy) while undertaking 
      supervised aerobic endurance training. On day 6 for both treatments, subjects 
      ingested an HCHO diet and rested before their experimental trials on day 7. This 
      CHO restoration resulted in similar resting glycogen contents (FAT-adapt 873 +/- 
      121 vs. HCHO 868 +/- 120 micromol glucosyl units/g dry wt). However, the 
      respiratory exchange ratio was lower during cycling at 70% VO2peak in the 
      FAT-adapt trial, which resulted in an approximately 45% increase and an 
      approximately 30% decrease in fat and CHO oxidation, respectively. PDH activity 
      was lower at rest and throughout exercise at 70% VO2peak (1.69 +/- 0.25 vs. 2.39 
      +/- 0.19 mmol x kg wet wt(-1) x min(-1)) and the 1-min sprint in the FAT-adapt 
      vs. the HCHO trial. Estimates of glycogenolysis during the 1st min of exercise at 
      70% VO2peak and the 1-min sprint were also lower after FAT-adapt (9.1 +/- 1.1 vs. 
      13.4 +/- 2.1 and 37.3 +/- 5.1 vs. 50.5 +/- 2.7 glucosyl units x kg dry wt(-1) x 
      min(-1)). HSL activity was approximately 20% higher (P = 0.12) during exercise at 
      70% VO2peak after FAT-adapt. Results indicate that previously reported decreases 
      in whole body CHO oxidation and increases in fat oxidation after the FAT-adapt 
      protocol are a function of metabolic changes within skeletal muscle. The 
      metabolic signals responsible for the shift in muscle substrate use during 
      cycling at 70% VO2peak remain unclear, but lower accumulation of free ADP and AMP 
      after the FAT-adapt trial may be responsible for the decreased glycogenolysis and 
      PDH activation during sprinting.
FAU - Stellingwerff, Trent
AU  - Stellingwerff T
AD  - Department of Human Biology and Nutritional Sciences, University of Guelph, 
      Ontario, Canada. trent.stellingwerff@bw.unimaas.nl
FAU - Spriet, Lawrence L
AU  - Spriet LL
FAU - Watt, Matthew J
AU  - Watt MJ
FAU - Kimber, Nicholas E
AU  - Kimber NE
FAU - Hargreaves, Mark
AU  - Hargreaves M
FAU - Hawley, John A
AU  - Hawley JA
FAU - Burke, Louise M
AU  - Burke LM
LA  - eng
PT  - Journal Article
PT  - Randomized Controlled Trial
PT  - Research Support, Non-U.S. Gov't
DEP - 20050927
PL  - United States
TA  - Am J Physiol Endocrinol Metab
JT  - American journal of physiology. Endocrinology and metabolism
JID - 100901226
RN  - 0 (Dietary Carbohydrates)
RN  - 0 (Pyruvate Dehydrogenase Complex)
SB  - IM
MH  - Adaptation, Physiological/physiology
MH  - Adipose Tissue/*physiology
MH  - Adult
MH  - Cross-Over Studies
MH  - Dietary Carbohydrates/*metabolism
MH  - Exercise/physiology
MH  - Glycogenolysis/*physiology
MH  - Humans
MH  - Muscle, Skeletal/*physiology
MH  - Physical Endurance/*physiology
MH  - Physical Exertion/*physiology
MH  - Pyruvate Dehydrogenase Complex/*metabolism
EDAT- 2005/09/29 09:00
MHDA- 2006/02/24 09:00
CRDT- 2005/09/29 09:00
PHST- 2005/09/29 09:00 [pubmed]
PHST- 2006/02/24 09:00 [medline]
PHST- 2005/09/29 09:00 [entrez]
AID - 00268.2005 [pii]
AID - 10.1152/ajpendo.00268.2005 [doi]
PST - ppublish
SO  - Am J Physiol Endocrinol Metab. 2006 Feb;290(2):E380-8. doi: 
      10.1152/ajpendo.00268.2005. Epub 2005 Sep 27.