Endurance in high-fat-fed rats: effects of carbohydrate content and fatty acid profile.
The purpose of this experiment was to study endurance performance and substrate storage and utilization in fat- or carbohydrate-fed rats. Ninety-nine rats were randomly divided into three groups and over 4 wk were fed either a carbohydrate-rich [CHO; 10% total energy content in the diet (E%) fat, 20 E% protein, 70 E% carbohydrate] diet or one of two fat-rich diets (65 E% fat, 20 E% protein, 15 E% carbohydrate) containing either saturated (Sat) or monounsaturated fatty acids (Mono). Each dietary group was randomly assigned to a trained (6 days/wk, progressive to 60 min, 28 m/min at a 10% incline) or a sedentary group. Rats were killed either before or after a treadmill endurance run to exhaustion. Training increased endurance (206%), but diet composition did not affect endurance in either trained or sedentary rats. beta-Hydroxyacyl-CoA dehydrogenase activity was increased in fat-fed but not carbohydrate-fed rats (P < 0.05). Respiratory exchange ratio during the initial phase of exercise was lower after the Mono compared with the Sat diet (P < 0. 05) and higher after the CHO than the Sat diet (P < 0.05). Thus adaptation to a high-fat diet containing a moderate amount of carbohydrates did not induce enhanced endurance in either trained or untrained rats; however, substrate utilization was modulated by both amount and type of dietary fat during the initial stage of exercise in trained and sedentary rats.
Helge
J W
JW
Copenhagen Muscle Research Centre, August Krogh Institute, DK-2100 Copenhagen O, Denmark. Jhelge@aki.ku.dk
Ayre
K
K
Chaunchaiyakul
S
S
Hulbert
A J
AJ
Kiens
B
B
Storlien
L H
LH
D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D050260:Carbohydrate Metabolism; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005080:Exercise Test; D005227:Fatty Acids / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D009928:Organ Specificity; D010805:Physical Conditioning, Animal / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D014280:Triglycerides / Q000378:metabolism*
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005227:Fatty Acids; D008112:Liver Glycogen; D014280:Triglycerides; D015094:3-Hydroxyacyl CoA Dehydrogenases