In a HIIT workout, the movements typically change every day. Some days are technical, when you focus on a snatch for 30 minutes before doing an intense 10-minute workout. Other days, you’ll do a “chipper,” moving for 40 minutes between a power clean (an Olympic lift), running, kettlebells, and throwing a medicine ball overhead at a wall, for example. The high-intensity part of the workout comes from the nonstop element; you do the prescribed movements until time is up or you’ve completed a set number of reps.
The goal is to improve overall fitness and home in on areas you can get stronger. You’ll find movements you love and ones you struggle with. If you’ve never done strength training, you may be surprised at how quickly you progress. If you want to improve your cardio and aerobic capacity, have no fear—your body’s ability to get oxygen to your muscles will skyrocket.
Once you get more experienced in cross-functional fitness, the benefits increase, studies have shown, with better aerobic capacity and more strength. Although you may hear about potential injuries, research has shown that the frequency of HIIT-related injuries is consistent with those associated with any type of fitness activity.
I was lured in by HIIT’s short workouts. Emily was effusive about how efficient the workouts were, and I loved the idea of pushing hard for 10 minutes—though I would soon find out many workouts lasted longer than that. I also hadn’t joined a new fitness community in years, and my interest was piqued when Emily described the program’s outgoing, encouraging culture. I wanted to meet new people, both to work out with and to build new friendships. Her CrossFit gym sounded like a jump-start for body and soul.
On the first day of the intro class, our trainer, Jenelle, eased us in. We learned proper squat technique and how to go deep into a squat by dropping our hips below our knees, and we worked on push-ups, modifying as needed with knees down. We made pull-ups easier by attaching a stretchy band to a bar and stepping into the bottom to get some needed lift up over the bar. I hadn’t attempted a pull-up in years and relied on the boost from the thick rubber band.
We did a timed workout—a HIIT staple—with a 200-meter sprint, running on pavement outside and around the block, followed by three rounds of air squats (squatting your hips below your knees), push-ups, and ring rows (holding a set of rings, walking your legs forward so your body is diagonal to the ground, and pulling your chest to the rings, a modification to build shoulder strength for pull-ups). We finished with a final sprint. Loud music pounded throughout the workout, and Jenelle shouted encouragement. I was breathing hard, but I liked it. We recorded our times in journals at the end of class.
I walked out of the gym energized by doing the workout and by meeting new people who lived close by and were intrigued by HIIT. I was excited about the next workout. Maybe it was the endorphins or an adrenaline buzz, but I almost skipped to my car.
Who was I? All it took was one workout to become one of them?
I thought about the workout for the next two days and couldn’t wait to go back, despite the soreness in my shoulders from the push-ups and pull-ups. I was excited every time I got to class; three times a week didn’t feel like enough.
As we progressed through the intro series, the workouts increased in length and intensity. The combination of cardio with strength training is brutal, if effective, even when the cardio is a short 200-meter sprint. I hate running, though I discovered I was a decent sprinter. But running tested my lungs; by the third round of sprinting, rowing, or jumping rope combined with pull-ups, squats, or lunges, I was gasping.
Finally, we had a workout with “no cardio.” We learned to do wallballs—taking a large, heavy medicine ball, squatting while holding the ball, and then standing up and heaving it up above a marked height on the wall.
Yes! I thought when I watched the demonstration. I was gonna love this.
Perhaps it was best I went in blind. Five rounds of wallballs combined with push-ups and pull-ups later, I was on the floor, panting (collapsing on the dirty gym floor became the norm; you get used to being grimy). In cross-functional fitness, the running joke is: Wanna do cardio? Lift faster.
I had heard from the internet that some gyms throw you in too hard, too fast, and I didn’t know if I would like the intensity. The intro series was a soft entry; I never felt overwhelmed, an indicator of a good gym.
HIIT also gave my competitive side a new outlet. It’s never far below the surface, but I hadn’t taken on a competitive physical activity since high school. With timed workouts, I wanted to come out on top every time. I watched the clock and other athletes, talking myself into moving even when I felt like another burpee was impossible.
After my intro series was over, I wanted to keep going.
I got strong fast doing cross-functional fitness, a common result when you go from no weightlifting to lifting three to four times a week. While I’d once thought I hated weightlifting, I found that what I actually hated was lifting weights on a machine. I fell in love with the dynamic movements of Olympic weightlifting.
I also discovered that it takes time to develop the endurance and capacity for the intense workouts, and I was sore a lot, sometimes hobbling for a couple of days. But I was amazed to see how much stronger I got.
With the ever-changing workouts found in HIIT, it’s difficult to avoid exercises you dislike. It took me a year to do more than one double-under in a row, whipping the jump rope around twice on one hop. I despaired when the options were a 5K run or a 5K row on the rowing machine. Throwing myself to the floor and hopping back up to jump and clap overhead for a burpee felt like the death of me.
It helps when others tackle a workout with you. I bonded with many members of my classes over workouts. As I got to know them, I figured out which people I was on par with physically. At night, I was glued to Facebook, where coaches posted workout times from the day, scrolling through everyone’s results. As I’ve said, I’m competitive.
I struggled for a while between pushing myself and overextending my body. My competitiveness got the best of me one summer, and I tweaked my shoulder. I took the injury seriously and scaled back until my shoulder healed. I modified my workouts, using a thicker band for pull-ups and reducing weight on my lifts. I found that even modified high-intensity interval workouts produce sweat and can cause post-workout collapse.
More importantly, HIIT had a huge impact on my perception of my own strength. Prior to the training, I couldn’t do a pull-up, or even come close, whereas I now consider doing one or two pull-ups a baseline.
Cross-functional fitness also shifted my approach to nutrition. I had done simple cleanses before, such as eliminating sugar or alcohol for a month. Otherwise, I assumed I ate well. Then I did my first-ever Whole30 nutrition challenge—hosted by my gym—and cut out sugar, processed carbs, dairy, alcohol, and grains. I realized that a diet packed with good protein and vegetables stabilized my energy and made me feel stronger during workouts.
The workouts became a staple in my life. For the first time ever, I loved going to the gym and pushing my body in new ways. I loved lifting heavy weights. It was a thrill to go to fitness classes and see how much stronger I was and how much more endurance I had.
Most HIIT programs emphasize meeting everyone at the start of class, cheering folks on until they finish, and building community. I loved giving people high fives as they ran past me and grimacing with my friends when workouts felt harder than I ever thought possible. I watched people of all shapes, sizes, ages, and fitness levels come in and get fit and strong.
For a friend’s 40th birthday, I went to a workout called the Fatal 40. Tons of us packed the gym, sweating through squats, power cleans, pull-ups, push-ups, burpees, and running. During one set of 40 burpees, I was exhausted. I didn’t want to do any burpees, let alone 40; I had a few moments when I was ready to skip the burpees to finish.