Today's session is designed to increase your FTP by working at a hard, sustainable power.Start with a solid 15 min warm-up then 5 min at Z3. Ride easy 5 min before the first effort. Do 3 X 12 min efforts in Z4/Z5, resting 10 min between each effort. You should aim for 10-15 watt below your FTP. This is as mentally demanding as it is physically!