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Muscle Glycogen Metabolism in Horses: Interactions Between Substrate Availability, Exercise Performance and Carbohydrate Administration

Lacombe, Véronique Anne
http://rave.ohiolink.edu/etdc/view?acc_num=osu1041621577

Abstract Details

2003, Doctor of Philosophy, Ohio State University, Veterinary Clinical Sciences.
Horses undertake recreational activities that decrease muscle glycogen stores. Similar to humans, muscle glycogen availability may influence exercise performance. In the first study, a model of glycogen depletion was developed and used to investigate the effect of muscle glycogen availability on the athletic capacity of horses. We demonstrated that exercise-induced muscle glycogen depletion was associated with a 60% decrease in anaerobic capacity during subsequent exercise, without effect on aerobic capacity. To rule out any confounding effects of other exercise-induced changes, a second study investigated the effects of muscle glycogen depletion and subsequent replenishment on athletic capacity. In a blinded crossover study, seven fit horses received either an intravenous glucose or saline infusion after exercise. Run time to fatigue, accumulated oxygen deficit and blood lactate concentration during a subsequent high-speed exercise test were greater for the horses with normal muscle glycogen concentration than for the horses with persistent muscle glycogen depletion. It was concluded that muscle glycogen availability influences anaerobic capacity and ability to perform high-intensity exercise in horses. Given the critical role of adequate glycogen stores in enabling optimal performance, the factors and mechanisms affecting muscle glycogen replenishment in horses were studied. We first demonstrated that intravenous glucose infusion (6g/kg) hastened muscle glycogen resynthesis compared to saline infusion. The effect of 3 isoenergetic diets of varying glycemic indices on the rates of muscle glycogen synthesis after exercise was evaluated in a crossover study. Seven horses received either a high soluble carbohydrate diet (grain, HCO), or a low soluble carbohydrate diet (hay, LCO), or a mixed diet (M) every 8 hours for 72 hours after exercise. We demonstrated that muscle glycogen resynthesis is slower in horses than in humans. Feeding high-glycemic index (HCO) meals hastened muscle glycogen replenishment compared to LCO and MCO diets by increasing blood glucose and insulin availability to skeletal muscle. Finally, insulin-sensitive glucose transporters (GLUT-4) were characterized in equine muscles by Western blotting. We demonstrated that exercise increased GLUT-4 protein content by 27%. Replenishment of muscle glycogen stores after carbohydrate administration, either by glucose infusion or diet, attenuated the increase in GLUT-4 protein content of skeletal muscle.
Kenneth Hinchcliff (Advisor)
226 p.
Biology, Veterinary Science
Anaerobic capacity; muscle glycogen resynthesis; glycemic index; GLUT-4 glucose transporter; lactate

Recommended Citations

Citations

  • Lacombe, V. A. (2003). Muscle Glycogen Metabolism in Horses: Interactions Between Substrate Availability, Exercise Performance and Carbohydrate Administration [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1041621577

    APA Style (7th edition)

  • Lacombe, Véronique. Muscle Glycogen Metabolism in Horses: Interactions Between Substrate Availability, Exercise Performance and Carbohydrate Administration. 2003. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1041621577.

    MLA Style (8th edition)

  • Lacombe, Véronique. "Muscle Glycogen Metabolism in Horses: Interactions Between Substrate Availability, Exercise Performance and Carbohydrate Administration." Doctoral dissertation, Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1041621577

    Chicago Manual of Style (17th edition)

osu1041621577
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This open access ETD is published by The Ohio State University and OhioLINK.