Abstract & Authors:展开
Context: Pre-exercise nutrient availability alters acute metabolic responses to exercise, which could modulate training responsiveness.
Objective: To assess acute and chronic effects of exercise performed before versus after nutrient ingestion on whole-body and intramuscular lipid utilization, and postprandial glucose metabolism.
Design: 1) Acute, randomised, crossover design (Acute Study); 2) 6-week, randomised, controlled design (Training Study).
Setting: General community.
Participants: Men with overweight/obesity (mean±SD, BMI: 30.2±3.5 kg.m-2 for Acute Study, 30.9±4.5 kg.m-2 for Training Study).
Interventions: Moderate-intensity cycling performed before versus after mixed-macronutrient breakfast (Acute Study) or carbohydrate (Training Study) ingestion.
Results: Acute Study - exercise before versus after breakfast consumption increased net intramuscular lipid utilization in type I (net change: -3.44±2.63% versus 1.44±4.18% area lipid staining, p < 0.01) and type II fibres (-1.89±2.48% versus 1.83±1.92% area lipid staining, p < 0.05). Training Study - postprandial glycemia was not differentially affected by 6-weeks of exercise training performed before versus after carbohydrate intake (p>0.05). However, postprandial insulinemia was reduced with exercise training performed before, but not after carbohydrate ingestion (p=0.03). This resulted in increased oral glucose insulin sensitivity (25±38 vs -21±32 mL.min-1.m-2; p=0.01), associated with increased lipid utilization during exercise (r=0.50, p=0.02). Regular exercise before nutrient provision also augmented remodelling of skeletal muscle phospholipids and protein content of the glucose transport protein GLUT4 (p<0.05).
Conclusions: Experiments investigating exercise training and metabolic health should consider nutrient-exercise timing, and exercise performed before versus after nutrient intake (i.e., in the fasted state) may exert beneficial effects on lipid utilisation and reduce postprandial insulinemia.
R M Edinburgh
J T Gonzalez
R M Edinburgh,H E Bradley,N-F Abdullah,S L Robinson,O J Chrzanowski-Smith,J -P Walhin,S Joanisse,K N Manolopoulos,A Philp,A Hengist,A Chabowski,F M Brodsky,F Koumanov,J A Betts,D Thompson,G A Wallis,J T Gonzalez