One of the newer members of the Spartan Pro Team, Rea Kolbl, shares one of her favorite training sessions.
Perform each set of two exercises in alternating fashion, executing 20 seconds of work with 10 seconds of rest. Complete each one four total times so that each set ends up being four minutes long. Rest 30 seconds between each set. Kolbl usually does this part with an elevation mask set at 12,000 feet.