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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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EFFECTS OF ENDURANCE RUNNING AND DIETARY FAT ON CIRCULATING GHRELIN AND PEPTIDE YY |
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Ryan R. Russel1,2, Kentz S. Willis3, Eric Ravussin1 and Enette D. Larson-Meyer1,3  |
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1Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA, 2Department of Kinesiology, Louisiana State University, Baton Rouge, LA, and 3University of Wyoming, Laramie, WY, USA . |
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© Journal of Sports Science and Medicine (2009) 8, 574 - 583 |
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| ABSTRACT | |||
| Ghrelin and peptide YY (PYY) are newly recognized gut peptides
involved in appetite regulation. Plasma ghrelin concentrations are elevated
in fasting and suppressed following a meal, while PYY concentrations are
suppressed in fasting and elevated postprandially. We determine whether
ghrelin and PYY are altered by a low-fat, high-carbohydrate (10% fat, 75%
carbohydrate) or moderate-fat, moderate-carbohydrate (35% fat, 50% carbohydrate)
diet and; whether these peptides are affected by intense endurance running
(which is likely to temporarily suppress appetite). Twenty-one endurance-trained
runners followed a controlled diet (25% fat) and training regimen for 3
days before consuming the low-fat or isoenergetic moderate-fat diet for
another 3 days in random cross-over fashion. On day 7 runners underwent
glycogen restoration and then completed a 90-minute pre-loaded 10-km time
trial on day 8, following a control breakfast. Blood samples were obtained
on days 4 and 7 (fasting), and day 8 (non-fasting) before and after exercise
for analysis of ghrelin, PYY, insulin and growth hormone (GH). Insulin,
GH, Ghrelin and PYY changed significantly over time (p < 0.0001) but
were not influenced by diet. Ghrelin was elevated during fasting (days 4
and 7), while insulin and PYY were suppressed. Following the pre-exercise
meal, ghrelin was suppressed ~17% and insulin and PYY were elevated ~157
and ~40%, respectively, relative to fasting (day 7). Following exercise,
PYY, ghrelin, and GH were significantly (p < 0.0001) increased by ~11,
~16 and ~813%, respectively. The noted disruption in the typical inverse
relationship between ghrelin and PYY following exercise suggests that interaction
of these peptides may be at least partially responsible for post-exercise
appetite suppression. These peptides do not appear to be influenced by dietary
fat intake.
Key words: Exercise-induced anorexia, gut peptides, appetite regulation, hunger, exercise. |
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