title: Muscle glycogen depletion and subsequent replenishment affect anaerobic capacity of horses.
abstract: The purpose of this study was to determine the effect of muscle glycogen depletion and subsequent replenishment on anaerobic capacity of horses. In a blinded crossover study, seven fit horses performed glycogen-depleting exercise on two occasions. Horses were infused after glycogen-depleting exercise with either 6 g/kg body wt of glucose as a 13.5% solution in 0.9% NaCl (Glu) or with 0.9% NaCl (Sal) of equivalent volume. Subsequently, horses performed a high-speed exercise test (120% of maximal rate of oxygen consumption) to estimate maximum accumulated oxygen deficit. Replenishment of muscle glycogen was greater (P < 0.05) in Glu [from 24.7 +/- 7.2 (SE) to 116.5 +/- 7 mmol/kg wet wt before and after infusion, respectively] than in Sal (from 23.4 +/- 7.2 to 47.8 +/- 5.7 mmol/kg wet wt before and after infusion, respectively). Run time to fatigue during the high-speed exercise test (97.3 +/- 8.2 and 70.8 +/- 8.3 s, P < 0.05), maximal accumulated oxygen deficit (105.7 +/- 9.3 and 82.4 +/- 10.3 ml O(2) equivalent/kg, P < 0.05), and blood lactate concentration at the end of the high-speed exercise test (11.1 +/- 1.4 and 9.2 +/- 3.7 mmol/l, P < 0.05) were greater for Glu than for Sal, respectively. We concluded that decreased availability of skeletal muscle glycogen stores diminishes anaerobic power generation and capacity for high-intensity exercise in horses.
authors.affiliation: Equine Exercise Physiology Laboratory, Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Tharp St., Columbus, OH 43210, USA.
authors.forename: V A
authors.initials: VA
authors.lastname: Lacombe
authors.forename: K W
authors.initials: KW
authors.lastname: Hinchcliff
authors.forename: R J
authors.initials: RJ
authors.lastname: Geor
authors.forename: C R
authors.initials: CR
authors.lastname: Baskin
mesh_terms: D015308:Anaerobic Threshold / Q000502:physiology*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000502:physiology; D002153:Calorimetry, Indirect; D005260:Female; D005947:Glucose / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D006400:Hematocrit; D006736:Horses / Q000502:physiology*; D007700:Kinetics; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D006003:Glycogen; D005947:Glucose