Regulation of fuel metabolism by preexercise muscle glycogen content and exercise intensity.

To date, the results of studies that have examined the effects of altering preexercise muscle glycogen content and exercise intensity on endogenous carbohydrate oxidation are equivocal. Differences in the training status of subjects between investigations may, in part, explain these inconsistent findings. Accordingly, we determined the relative effects of exercise intensity and carbohydrate availability on patterns of fuel utilization in the same subjects who performed a random order of four 60-min rides, two at 45% and two at 70% of peak O(2) uptake (Vo(2 peak)), after exercise-diet intervention to manipulate muscle glycogen content.

Reduced neuromuscular activity with carbohydrate ingestion during constant load cycling.

The purpose of this study was to determine the effect of carbohydrate ingestion before and during intense constant load cycling to volitional fatigue on surface electromyographic (sEMG) activity from the vastus lateralis (VL) and vastus medialis (VM) muscles. After 24-h diet and training control, 8 well-trained subjects (maximal O(2 )uptake (VO(2max )) 66+/- 2 ml. kg-1.

Regulation of metabolic genes in human skeletal muscle by short-term exercise and diet manipulation.

Changes in dietary macronutrient intake alter muscle and blood substrate availability and are important for regulating gene expression. However, few studies have examined the effects of diet manipulation on gene expression in human skeletal muscle. The aim of this study was to quantify the extent to which altering substrate availability impacts on subsequent mRNA abundance of a subset of carbohydrate (CHO)- and fat-related genes.

Effect of carbohydrate ingestion on metabolism during running and cycling.

The effects of carbohydrate or water ingestion on metabolism were investigated in seven male subjects during two running and two cycling trials lasting 60 min at individual lactate threshold using indirect calorimetry, U-14C-labeled tracer-derived measures of the rates of oxidation of plasma glucose, and direct determination of mixed muscle glycogen content from the vastus lateralis before and after exercise. Subjects ingested 8 ml/kg body mass of either a 6.4% carbohydrate-electrolyte solution (CHO) or water 10 min before exercise and an additional 2 ml/kg body mass of the same fluid after 20 and 40 min of exercise.

Pacing strategy in simulated cycle time-trials is based on perceived rather than actual distance.

This study determined the pacing strategies and performance responses of six well-trained cyclists/triathletes (peak O2 uptake 66.4+/-3.7 ml x kg(-1) x min(-1), mean+/-SD) during seven simulated time-trials (TT) conducted on a wind-braked cycle ergometer.