Blood and muscle metabolic responses to draught work of varying intensity and duration in horses.
Three standardbred trotters performed treadmill exercise at a velocity of 2 m s-1 with a draught load of both 34 kiloponds (kp) (test 1) and 80 kp (test 2), and also at 7 m s-1 with 34 kp (test 3). The heart rate increased to average values of 111 (+/- 5), 157 (+/- 10) and 197 (+/- 7) beats min-1 in tests 1, 2, and 3, respectively. Plasma free fatty acids increased only during tests 1 and 2. Blood lactate and muscle glucose-6-phosphate and lactate concentrations were low after tests 1 and 2, but high after test 3, where also muscle glycogen utilisation was greatest. Muscle creatine phosphate and adenosine triphosphate concentrations decreased after test 3 only. The study indicates that oxidative metabolism is most important for energy supply in muscles when exercise is performed with draught loads of both 34 and 80 kp at a low velocity. Glycogenolysis with lactate accumulation and phosphagen breakdown becomes much more important when, with a draught load of 34 kp, the velocity of exercise increases.
Swedish University of Agricultural Sciences, Faculty of Veterinary Medicine, Department of Medicine and Surgery, Uppsala, Sweden.
M
M
Gottlieb
B
B
Essén-Gustavsson
H
H
Skoglund-Wallberg
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D019298:Glucose-6-Phosphate; D005958:Glucosephosphates / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006339:Heart Rate; D006736:Horses / Q000097:blood / Q000378:metabolism* / Q000502:physiology; D007773:Lactates / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D005082:Physical Exertion
D005230:Fatty Acids, Nonesterified; D005958:Glucosephosphates; D007773:Lactates; D010725:Phosphocreatine; D019298:Glucose-6-Phosphate; D000255:Adenosine Triphosphate; D006003:Glycogen