Exercise time to exhaustion during HIE was not significantly different between trials: nor were the rates of muscle glycogen utilization during HIE different between trials, although starting muscle glycogen content was lower [...] after the HIGH-FAT diet. Despite a lower muscle glycogen content at the onset of MIE [...], exercise time to exhaustion during subsequent MIE was significantly longer after the HIGH-FAT diet [...].
In plain English? The difference in time from start to exhaustion is not significant, despite the glycogen storage being lower in the high fat group.
Conclusion? The body needing carbs for training is a myth.