I frequently mention HIIT – high-intensity interval training – on Facebook and Twitter because it’s my get-it-done cardio method. I get bored doing long bouts on the elliptical and HIIT makes the time go fast. Not only can I burn calories but I feel energetic for hours after HIIT and have seen my aerobic endurance increase.
And just as with weightlifting, you need to vary your cardio workouts to continue seeing results. If you use the same speed, for same amount of time, on the same 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, building more endurance, and gaining more strength.
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 says:
“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. It also increases your cardiorespiratory endurance.
HIIT is not for everyone and requires an intermediate to advanced level of fitness. You need to have the ability to stay at about 90% of your maximum heart rate for 30 seconds and return to a lower heart rate fairly quickly. You can work up to longer bouts of intense “sprint” intervals and do HIIT at a lower intensity until you get there.
You can use a succession of bodyweight exercises for HIIT, outdoor running/sprinting, or cardio machines such as the elliptical, treadmill, or stationary bike. You also need access to a heart rate monitor (see below).
With HIIT, your sprint 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.
Using a Heart Rate Monitor for HIIT
You can use a heart rate monitor to get an instant, accurate reading of your heart rate (but keep in mind that the formula for knowing your max heart rate number can be very inaccurate). Using the monitors on the cardio machines means you have to grasp the bars and wait for the results. You’ll be doing short blasts (30 to 60 seconds) of work – you want an instant feedback so you can reduce the intensity a bit or amp it up accordingly.
The first step is to find your maximum heart rate. Subtract your age from 220. The three heart rate zones you need to target are:
Zone 1: 65-75% Used as a warm up and recovery zone
Zone 2: 80-85% Sprint zone
Zone 3: 86-90% Sprint interval zone for experienced HIIT users
Next, find out your target heart rates for each zone. Multiply your maximum heart rate by the percentage. For example, a 30-year-old’s heart rate max would be 190 (220-30). Her warm-up heart rate is around 133 (190 x .70), her recovery zone is around 161 (190 x .85), and her sprint zone is 171 (190 x .90).
Here’s a sample beginner HIIT routine:
- 5 minute warm up – 65-75% of maximum heart rate
- 30 seconds – 80-85% max
- 1 minute – 70-75% max (recovery)
- 30 seconds – 86-90% max (all-out effort)
- 90 seconds – 70-75% max (recovery)
- Repeat steps 2 through 5 for a total of 20 minutes.
- 5 minute cool down – 60% of max rate
Using RPE for HIIT
A simpler method of measuring how hard you’re working and which requires no equipment is rate of perceived exertion (RPE). Click here to learn more.