Today’s workout is a simple interval training session that can be performed on a treadmill, out on a track or, if you prefer not to run, using a rower.
Starting every 3rd minute run/row 400 meters. Perform five intervals.
The faster you run/row, the longer you get to rest (!)
Start your next interval at the top of each three minutes.
Try to keep your pace relatively even across all your intervals. 
