The keys to performing lactic intervals are: • Use a work period of 30-40 seconds at 100% intensity • Cover as much distance during the work period as possible while maintaining proper technique • Cover as close to the same distance as possible during each work period • Actively recover 1-4 minutes, depending on the level of the athlete • Perform 2-5 reps, depending on the level of the athlete This is a highly fatiguing method, so it’s important to train proper technique as fatigue develops. Use mechanical cues rather than speed cues to help athletes reinforce good movement habits. This is an ideal method for using dynamic energy control to drive the heart rate down between work periods. Gauge the athlete’s 60-second heart rate recovery to measure his/her effectiveness at controlling energy output. Keep in mind that the rest interval is just as important as the work interval. The rest interval, when done effectively, adequately prepares athletes to perform the next work interval. You can help athletes develop core stability under fatigue by transitioning them to a plank immediately following their lactic intervals.