PMID- 16141377
OWN - NLM
STAT- MEDLINE
DCOM- 20060201
LR  - 20130926
IS  - 8750-7587 (Print)
IS  - 0161-7567 (Linking)
VI  - 100
IP  - 1
DP  - 2006 Jan
TI  - Fat adaptation followed by carbohydrate loading compromises high-intensity sprint 
      performance.
PG  - 194-202
AB  - The aim of this study was to investigate the effect of a high-fat diet (HFD) 
      followed by 1 day of carbohydrate (CHO) loading on substrate utilization, heart 
      rate variability (HRV), effort perception [rating or perceived exertion (RPE)], 
      muscle recruitment [electromyograph (EMG)], and performance during a 100-km 
      cycling time trial. In this randomized single-blind crossover study, eight 
      well-trained cyclists completed two trials, ingesting either a high-CHO diet 
      (HCD) (68% CHO energy) or an isoenergetic HFD (68% fat energy) for 6 days, 
      followed by 1 day of CHO loading (8-10 g CHO/kg). Subjects completed a 100-km 
      time trial on day 1 and a 1-h cycle at 70% of peak oxygen consumption on days 3, 
      5, and 7, during which resting HRV and resting and exercising respiratory 
      exchange ratio (RER) were measured. On day 8, subjects completed a 100-km 
      performance time trial, during which blood samples were drawn and EMG was 
      recorded. Ingestion of the HFD reduced RER at rest (P < 0.005) and during 
      exercise (P < 0.01) and increased plasma free fatty acid levels (P < 0.01), 
      indicating increased fat utilization. There was a tendency for the low-frequency 
      power component of HRV to be greater for HFD-CHO (P = 0.056), suggestive of 
      increased sympathetic activation. Overall 100-km time-trial performance was not 
      different between diets; however, 1-km sprint power output after HFD-CHO was 
      lower (P < 0.05) compared with HCD-CHO. Despite a reduced power output with 
      HFD-CHO, RPE, heart rate, and EMG were not different between trials. In 
      conclusion, the HFD-CHO dietary strategy increased fat oxidation, but compromised 
      high intensity sprint performance, possibly by increased sympathetic activation 
      or altered contractile function.
FAU - Havemann, L
AU  - Havemann L
AD  - University of Cape Town/Medical Research Council Research Unit for Exercise 
      Science and Sports Medicine, Department of Human Biology, University of Cape 
      Town, South Africa.
FAU - West, S J
AU  - West SJ
FAU - Goedecke, J H
AU  - Goedecke JH
FAU - Macdonald, I A
AU  - Macdonald IA
FAU - St Clair Gibson, A
AU  - St Clair Gibson A
FAU - Noakes, T D
AU  - Noakes TD
FAU - Lambert, E V
AU  - Lambert EV
LA  - eng
PT  - Journal Article
PT  - Randomized Controlled Trial
PT  - Research Support, Non-U.S. Gov't
DEP - 20050901
PL  - United States
TA  - J Appl Physiol (1985)
JT  - Journal of applied physiology (Bethesda, Md. : 1985)
JID - 8502536
RN  - 0 (Dietary Carbohydrates)
RN  - 0 (Dietary Fats)
SB  - IM
CIN - J Appl Physiol (1985). 2006 Jan;100(1):7-8. PMID: 16357078
MH  - Adaptation, Physiological/physiology
MH  - Adult
MH  - Cross-Over Studies
MH  - Dietary Carbohydrates/*metabolism
MH  - Dietary Fats/*metabolism
MH  - Exercise Test
MH  - Heart Rate/physiology
MH  - Humans
MH  - Male
MH  - Muscle, Skeletal/*physiology
MH  - Oxygen Consumption/physiology
MH  - Physical Endurance/*physiology
MH  - Physical Exertion/*physiology
MH  - *Psychomotor Performance
MH  - Running/*physiology
MH  - Single-Blind Method
EDAT- 2005/09/06 09:00
MHDA- 2006/02/02 09:00
CRDT- 2005/09/06 09:00
PHST- 2005/09/06 09:00 [pubmed]
PHST- 2006/02/02 09:00 [medline]
PHST- 2005/09/06 09:00 [entrez]
AID - 00813.2005 [pii]
AID - 10.1152/japplphysiol.00813.2005 [doi]
PST - ppublish
SO  - J Appl Physiol (1985). 2006 Jan;100(1):194-202. doi: 
      10.1152/japplphysiol.00813.2005. Epub 2005 Sep 1.