SPRINT PYRAMID
  Today's  workout may look complicated, but it really isn't. Run sprints of 10,  15, 20, 30, 20, 15, and 10 seconds with 1 minutes recovery in between  (90 seconds on each side of the 30 second sprint).
 - 5 minutes - Run or Run-walk
 - 10 seconds – Sprint
 - 1 minute – Recovery
 - 15 seconds – Sprint
 - 1 minute – Recovery
 - 20 seconds – Sprint
 - 90 seconds – Recovery
 - 30 seconds – Sprint
 - 90 seconds – Recovery
 - 20 seconds – Sprint
 - 1 minute – Recovery
 - 15 seconds – Sprint
 - 1 minute – Recovery
 - 10 seconds – Sprint
 - 1 minute – Recovery
 - 5 minutes - Run or Run-walk