Session - 6 x 3' rest 3' divided into 90 seconds at 90-95% followed by 60 seconds at 105-110% followed by a big second 30 seconds greater than 130%. Do a thorough warm up for at least 10'. I prefer a 15' progressive warm up with many 20-30 seconds sprints at target pace. Key here is in the first 3-5 strokes/rpm - big power extremely quick recovery, keep the drive tight and full. Use the 3' to gently recover, it's good to move rather than staying fixed.