HIIT workouts are efficient, but to enjoy their calorie-burning, heart-healthy benefits you're going to have to push yourself. HIIT is all about spiking the heart rate and feeling sweaty, out of breath and uncomfortable.
The good news is the workout will be over before you know it. All high-intensity workouts, no matter your fitness level, should last no longer than 30 minutes, including warm up and cool down.
Anything longer than that, says Erin Beck, a fitness coach and owner of eTONE Fitness, and you're sacrificing intensity and power for duration. Pushing the duration too long means you aren't hitting the sweet spot of intensity.
The length and frequency of HIIT workouts - 30 minutes, three to five times a week - is fairly standard, but the ideal work-to-rest ratio within each session depends on your fitness level.
Beginners and those new to high intensity training should start with a 1:2 ratio of high intensity to rest. This means you push the intensity for 30 seconds, then rest for a minute. Intermediate athletes can work at a 1:1 ratio, either a minute on and a minute off or 30 seconds on and 30 seconds off, depending on the exercise. Advanced athletes can hit a 2:1 work to rest ratio, 30 seconds on and 15 seconds off.
If you're not sure where you fall in the beginner-to-advanced spectrum, listen to your body. How do you know if you're pushing hard enough during these intervals? One way is by checking your heart rate during the rest periods.
First, determine your maximum heart rate by subtracting your age from 220. If you're 40, your maximum is 180. You want to hit 80 to 95 percent of this number in your work interval, so during your rest interval take your pulse and count the beats for six seconds. Multiply that number by ten and you'll have your heart rate. A 40-year-old needs to keep her heart rate at about 16 or 17 beats per six seconds, for a heart rate of 160 or 170.
If, like me, you prefer to spend your rest time hunched over and panting, you can use a heart rate monitor or just go by your feeling of breathlessness.
If you're gasping for breath at the end of the interval, you're doing it right. "Your body never lies. Your heart rate sometimes will."
You don't need equipment or even much space to hit your target zone. Exercises that use your entire body, like shadow boxing or kickboxing, are excellent low-impact ideas for a HIIT workout. Other great low impact options are lunges and squats, and you can add a punch at the top of your squat for a full-body move.
How to motivate on your own
As I've discovered during my months of solitary sweating, the hardest part of solo HIIT workouts is finding the motivation to push yourself without a coach telling you to keep moving.
Atkinson has two tricks to keep her motivated. The first is using an interval timer app. The clock ticking down "creates a sense of urgency. So if you can attach that thought process, 'I'm blowing it if I don't get to breathless before this is done,' that can help," said Debra Atkinson, founder of Flipping Fifty, which offers hormone-balancing exercise for women in menopause
Her second trick is putting on fast music - between 160 and 180 beats per minute. "Your body will naturally try to go faster to the beat during a faster song," she said. (Spotify has playlists organized by BPM in the Running section.)
Consider finding an accountability partner or friend to keep you on track. Many fitness trackers can sync with another person's tracker, which means no more pretending you worked out in your garage when you really stayed in bed repeatedly hitting the snooze button.
For Beck, the best way to stay motivated is by tracking and measuring your progress. She recommends what she calls "marking your start," which means writing down what you accomplished on day one of your workout program.
"Train for a week, then check back on those numbers and see how much you've improved," she says. "The only way we'll be able to see if we're getting stronger is if we know where we started. Then we can see how far we've come."
Hilary Achauer is a health, wellness, and parenting writer based in San Diego.