MICRO BURST INTERVALS ARE BACK - THE SEQUEL! An extended, progressive warm-up includes a series of short/sharp 'spikes' is designed to get you fully warmed-up and primed for six sets of varied micro burst intervals. The session feature three blocks of short (hard) intervals, repeated twice through. The intervals are 20/15/10 seconds respectively - but as the time decreases, we increased power / decrease rest and add an extra rep too.