Sprint Intervals!
Make sure you warm up effectively before jumping into this one. Run about 3 min, followed by 30 sec each of:
High Knees
Butt Kicks
Side Shuffle (Right and Left)
Carioca (Right and Left)
Skips
Then 10 meter sprints. Perform 10 runs, increasing pace with each one until you finish at a full sprint.
Workout:
Find a hill for this one! You'll need a distance of about 30-40 yards. Every 90 seconds, do 5 burpees as fast as possible, then sprint hard up the hill. Walk back down. Rest until for the remainder of the 90 seconds. Do 10 rounds for intermediate, 15 for advanced.