title: Ingestion of starch-rich meals after exercise increases glucose kinetics but fails to enhance muscle glycogen replenishment in horses.
abstract: Fatiguing exercise substantially decreases muscle glycogen concentration in horses, impairing athletic performance in subsequent exercise bouts. Our objective was to determine the effect of ingestion of starch-rich meals after exercise on whole body glucose kinetics and muscle glycogen replenishment. In a randomized, cross-over study seven horses with exercise-induced muscle glycogen depletion were either not fed for 8 h, fed half of the daily energy requirements ( approximately 15 Mcal DE) as hay, or fed an isocaloric amount of corn 15 min and 4 h after exercise. Starch-rich meals fed after exercise, when compared to feed withholding, resulted in mild to moderate hyperglycemia (5.7+/-0.3 vs. 4.7+/-0.3 mM, P<0.01) and hyperinsulinemia (79.9+/-9.3 vs. 39.0+/-1.9 pM, P<0.001), 3-fold greater whole body glucose kinetics (15.5+/-1.4 vs. 5.3+/-0.4 micromol kg(-1)min(-1), P<0.05), but these only minimally enhanced muscle glycogen replenishment (171+/-19 vs. 170+/-56 and 260+/-45 vs. 294+/-29 mmol/kg dry weight immediately and 24 h after exercise, P>0.05). It is concluded that after substantial exercise-induced muscle glycogen depletion, feeding status only minimally affects net muscle glycogen concentrations after exercise, despite marked differences in soluble carbohydrate ingestion and availability of glucose to skeletal muscle.
authors.affiliation: Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH 43210, USA. eduard.jose-cunilleras@aht.org.uk
authors.forename: Eduard
authors.initials: E
authors.lastname: Jose-Cunilleras
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Hinchcliff
authors.forename: Veronique A
authors.initials: VA
authors.lastname: Lacombe
authors.forename: Richard A
authors.initials: RA
authors.lastname: Sams
authors.forename: Catherine W
authors.initials: CW
authors.lastname: Kohn
authors.forename: Lynn E
authors.initials: LE
authors.lastname: Taylor
authors.forename: Steven T
authors.initials: ST
authors.lastname: Devor
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D018592:Cross-Over Studies; D005260:Female; D005947:Glucose / Q000493:pharmacokinetics*; D006003:Glycogen / Q000378:metabolism*; D006736:Horses / Q000378:metabolism*; D007328:Insulin / Q000097:blood / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D013213:Starch / Q000494:pharmacology*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D013213:Starch; D006003:Glycogen; D005947:Glucose