Macro partitioning

Training with low muscle glycogen increases fat oxidation and muscle-derived triacylglycerol oxidation in well-trained cyclists without improving time trial performance compared to high glycogen training.

If you are a well-trained cyclist, you can train with low muscle glycogen (by doing two sessions close together without eating between them) to improve your body's ability to burn fat. However, this will not make you faster in time trials compared to training with full glycogen, and you will likely have to ride at a lower intensity during high-intensity intervals. This strategy is useful for metabolic flexibility but not for maximizing speed or power output.