Don't forget to warm up properly before each of these workouts.
Example sprint run
2 rounds: 5x20-40 meter sprints w/full recovery in between each (2 minutes) and 4 minutes rest between sets. "Effort is key here," Holder says. "Progressively increase the amount of sprints and distance you do as you move through weeks." If you can find a hill to do this on, even better. You can also do this on a stationary bike, Holder says. "A good circuit is 8-second bike sprint, 12-second recovery for 20 minutes, 3x a week; this has been proven to promote fat loss and muscle gain," he adds.