The Best of Both Worlds
This isn’t meant to be an indictment of interval training. As Jamieson points out, “It increases the endurance of the faster- twitch muscle fibers,” the big ones you use to lift heavy weights or run fast. Intervals can play a critical role in preparing you for any quick-burst sports you engage in. HIIT also burns calories and makes for fun workouts you can do when short on time. But because it’s so intense by nature, you have to use it sparingly. “With lower-intensity training,” says Jamieson, “we can do more work without being worried about what it might do to recovery. High-intensity training has to be managed properly because it’s very easy to overtrain.”
So, to maximize your cardiovascular fitness, he advises that you cap your HIIT sessions at 20–30 minutes, and spread them out—do intervals on Monday and Thursday, for example. Aerobic training, on the other hand, can be done virtually every day, although you need only three to four sessions of 20–30 minutes per week—building up to 90 minutes over time—to see results. The right balance of aerobic and anaerobic cardio conditions the body to perform any activity better—and does as much as cardio can to help you burn fat.