Originally Posted by
mr_pedro
The graph is not implying anyone to ride at 105% FTP for 1 hour. The unit of the vertical axis is kCal per hour, however that does not mean you need to ride for 1 hour, just like riding at 20 mph can also be done for 30 minutes.
How can they denote kCal per hour?
One person's 100% FTP may burn 1300 kCal an hour, whereas someone else's may only burn 600.