I get bored with long bouts of cardio on the elliptical, but high-intensity interval training (HIIT) makes the time go fast. Not only can I burn calories, but I feel energetic for hours after HIIT. When I’m consistent, I’ve also seen my aerobic endurance increase.
Plenty of studies have reported that HIIT raises your resting metabolism and burns 10% more calories over a 24-hour period than steady state. Other studies have shown that more body fat is dropped when using a HIIT program over a period of weeks than with steady state.
A researcher from a March 2010 study said:
“Doing 10 one-minute sprints on a standard stationary bike with about one minute of rest in between, three times a week, works as well in improving muscle as many hours of conventional long-term biking less strenuously.”
Keep in mind that low-intensity endurance cardio still has a place in your workouts. Endurance cardio also increases your mitochondria and thus you’re body’s ability to burn fat more efficiently. “Steady-state” cardio also increases your cardiorespiratory endurance.
- You need to start where you are with HIIT. If you’re not already doing some sort of cardio, you may find yourself winded very quickly. Sure, you’re resting between “sprints,” but you’ll still be tired out before finishing. Even if you already do cardio, HIIT might kick your ass. So it’s perfectly fine to work up using longer rest periods and lower intensities.
- As with strength training, you need to vary your HIIT workouts to continue seeing results. If you use the same speed, rest to work ratio, and machine day after day, your body will soon adapt and stop working as hard. You’ll be in a replay loop instead of losing more weight and building more endurance.
However, HIIT is made for variety: You can use bodyweight exercises, outdoor running/sprinting, or cardio machines such as the elliptical, treadmill, or stationary bike. You can use a heart rate monitor to gauge your workout intensity, but it’s easier to estimate using your rate of perceived exertion (RPE).
- With HIIT, your work periods need to be at a high intensity to get the benefits of the calorie burn and after-burn effect (EPOC). That’s not a level we can maintain for very long, thus the short intense periods of HIIT. The active recovery intervals can be longer and are just that – a chance for your heart rate to come back down to a moderate level. And that’s also why you need a heart rate monitor.
- Do not do HIIT more than two to three times per week and allow time to recover between workouts.
Methods for Monitoring Intensity
Since heart rate max formulas based on age are nebulous, I’m a proponent of listening to your body. If you’re using a heart rate monitor, you can figure out what your max is just by working hard as hell for a 30-second blasts and get instant feedback about what you can tolerate. I would not rely on the heart rate mechanisms in cardio machines.
A simpler method of measuring how hard you’re working and which requires no equipment is rate of perceived exertion (RPE), which lets you rate your level of exertion using a simple scale.
Here’s a sample beginner HIIT routine. Keep in mind that you may need a longer warm up, depending on your fitness level and age. It may also take longer than these rest periods to lower your heart rate. Take it at your own pace and work up to more intensity and shorter rests.
- 5-10 minute warm up – RPE of 2-3 or 65-75% of max HR
- 30 seconds work – RPE of 8-9 or 80-85% max HR
- 1 minute recovery – RPE of 6-7 or 70-75% max HR
- 30 seconds work – RPE of 8-9 or 85-90% max HR (all-out effort)
- 90 seconds recovery – RPE of 6-7 or 70-75% max HR
- Repeat steps 2 through 5 for a total of 20 minutes
- 5-10 minute cool down – RPE of 2-3 or 60% of max HR