If I told you that there was a way to burn more calories, lose more fat, and improve your cardiovascular fitness level while spending less time doing cardio, you’d probably reach for your phone to report me to the consumer fraud hotline, right?
Well, this is one of those rare times when your natural it’s-too-good-to-be-true reaction could be mistaken. If you want to take your fitness and fat loss to the next level—without spending more time in the gym—then high intensity interval training (also known as HIIT) could be exactly what you're looking for.
Before getting into the details, notice that I didn’t say HIIT would be easier, just that it would take less of your time. In fact, the HIIT approach to cardio exercise is very physically demanding and isn’t for everyone. If you have any cardiovascular problems or other health concerns that limit your ability to exercise at very intense levels, or if you are relatively new to aerobic exercise or not already in good shape, HIIT is not for you—at least for now. If you have any doubts or concerns about whether it might be safe for you, check in with your medical professional before trying HIIT.
What It Is and How It Works
- HIIT is a specialized form of interval training that involves short intervals of maximum intensity exercise separated by longer intervals of low to moderate intensity exercise. Because it involves briefly pushing yourself beyond the upper end of your aerobic exercise zone, it offers you several advantages that traditional steady-state exercise (where you keep your heart rate within your aerobic zone) can’t provide:
- HIIT trains and conditions both your anaerobic and aerobic energy systems. You train your anaerobic system with brief, all-out efforts, like when you have to push to make it up a hill, sprint the last few hundred yards of a distance race, or run and hide from your spouse when they won't stop nagging you about the dishes.
- HIIT increases the amount of calories you burn during your exercise session and afterward because it increases the length of time it takes your body to recover from each exercise session.
- HIIT causes metabolic adaptations that enable you to use more fat as fuel under a variety of conditions. This will improve your athletic endurance as well as your fat-burning potential.
- HIIT appears to limit muscle loss that can occur with weight loss, in comparison to traditional steady-state cardio exercise of longer duration.
- To get the benefits HIIT, you need to push yourself past the upper end of your aerobic zone and allow your body to replenish your anaerobic energy system during the recovery intervals.
The key element of HIIT that makes it different from other forms of interval training is that the high intensity intervals involve maximum effort, not simply a higher heart rate. There are many different approaches to HIIT, each involving different numbers of high and low intensity intervals, different levels of intensity during the low intensity intervals, different lengths of time for each interval, and different numbers of training sessions per week. If you want to use HIIT to improve performance for a particular sport or activity, you’ll need to tailor your training program to the specific needs and demands of your activity.
General HIIT GuidelinesHIIT is designed for people whose primary concerns are boosting overall cardiovascular fitness, endurance, and fat loss, without losing the muscle mass they already have.
Before starting any HIIT program, you should be able to exercise for at least 20-30 minutes at 70-85% of your estimated maximum heart rate, without exhausting yourself or having problems.
Because HIIT is physically demanding, it’s important to gradually build up your training program so that you don’t overdo it. (The sample training schedule below will safely introduce you to HIIT over a period of eight weeks.)
Always warm up and cool down for at least five minutes before and after each HIIT session.
Work as hard as you can during the high intensity intervals, until you feel the burning sensation in your muscles indicating that you have entered your anaerobic zone. Elite athletes can usually sustain maximum intensity exercise for three to five minutes before they have to slow down and recover, so don’t expect to work longer than that.
Full recovery takes about four minutes for everyone, but you can shorten the recovery intervals if your high intensity intervals are also shorter and don’t completely exhaust your anaerobic energy system.
If you experience any chest pain or breathing difficulties during your HIIT workout, cool down immediately. (Don't just stop or else blood can pool in your extremities and lightheadedness or faintness can occur.)
If your heart rate does not drop back down to about 70% of your max during recovery intervals, you may need to shorten your work intervals and/or lengthen your recovery intervals.
HIIT (including the sample program below) is not for beginner exercisers or people with cardiovascular problems or risk factors. If you have cardiovascular problems or risk factors should NOT attempt HIIT unless your doctor has specifically cleared you for this kind of exercise.
A Sample Progressive HIIT ProgramPlease adhere to the general HIIT guidelines above for this program. To maximize fat loss, maintain an intensity level of 60-70% of your maximum heart rate (RPE of 5-6 on the 10-point scale) during warm up, cool down and recovery intervals.
After completing this eight-week program, you can continue working to increase the number of work intervals per session, the duration of work intervals, or both.
You can adjust this training plan to accommodate your particular needs and goals. If you find that this schedule is either too difficult or too easy for your current fitness level, you can make adjustments to the duration and/or number of high intensity intervals as necessary. For example, if you want to train yourself for very short, frequent bursts of maximum intensity activity, your program could involve sprinting for 20 seconds and jogging/walking for 60 seconds, and repeating that 15-20 times per session.
You don’t need to swap all of your aerobic exercise for HIIT to gain the benefits. A good balance, for example, might be two sessions of HIIT per week, along with 1-2 sessions of steady-state aerobic exercise. As usual, moderation is the key to long-term success, so challenge yourself—but don’t drive yourself into the ground. Get ready to see major changes in your body and your fitness level!