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.
Copenhagen Muscle Research Centre, August Krogh Institute, DK-2100 Copenhagen O, Denmark. Jhelge@aki.ku.dk
J W
JW
Helge
K
K
Ayre
S
S
Chaunchaiyakul
A J
AJ
Hulbert
B
B
Kiens
L H
LH
Storlien
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