Effects of feeding meals with various soluble-carbohydrate content on muscle glycogen synthesis after exercise in horses.
OBJECTIVE
To determine effects of feeding diets with various soluble-carbohydrate (CHO) content on rates of muscle glycogen synthesis after exercise in horses.


METHODS
7 fit horses.


METHODS
In a 3-way crossover study, horses received each of 3 isocaloric diets (a high soluble CHO [HC] diet, a low soluble CHO [LC] diet, or a mixed soluble CHO [MC] diet). For each diet, horses were subjected to glycogen-depleting exercise, followed by feeding of the HC, LC, or MC diet at 8-hour intervals for 72 hours.


RESULTS
Feeding the HC diet resulted in a significantly higher glycemic response for 72 hours and significantly greater muscle glycogen concentration at 48 and 72 hours after exercise, compared with results after feeding the MC and LC diets. Muscle glycogen concentrations similar to baseline concentrations were detected in samples obtained 72 hours after exercise in horses when fed the HC diet. Rate of glycogen synthesis was significantly higher when horses were fed the HC diet, compared with values when horses were fed the MC and LC diets. Glycogen synthase activity was inversely related to glycogen content. Protein content of glucose transporter-4 was the lowest at 72 hours after exercise when horses were fed the HC diet.


CONCLUSIONS
Muscle glycogen synthesis was slower after glycogen-depleting exercise in horses, compared with synthesis in humans. Feeding HC meals after strenuous exercise hastened replenishment of muscle glycogen content, compared with results for feeding of LC and MC diets, by increasing availability of blood glucose to skeletal muscles.
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
Véronique A
VA
Lacombe
Kenneth W
KW
Hinchcliff
Catherine W
CW
Kohn
Stephen T
ST
Devor
Lynn E
LE
Taylor
D000704:Analysis of Variance; D000818:Animals; D001786:Blood Glucose; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005470:Fluorometry; D051275:Glucose Transporter Type 4; D006003:Glycogen / Q000096:biosynthesis*; D006006:Glycogen Synthase / Q000378:metabolism*; D006736:Horses / Q000502:physiology*; D019344:Lactic Acid / Q000097:blood; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D010805:Physical Conditioning, Animal
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D019344:Lactic Acid; D006003:Glycogen; D006006:Glycogen Synthase