Why HIIT Is a Fit-for-Wherever Workout

Fast and flexible, high-intensity interval training is ideal for our increasingly unpredictable work lives.

By Erin Wong April 2, 2021

Our hearts took a beating in 2020, but some managed to come out stronger. Online fitness classes surged during coronavirus and, yoga aside, one form of exercise outpaced the rest: HIIT. High-intensity interval training was the second-most popular digital workout worldwide, according to a ClassPass analysis of 30,000 boutique studios and gyms. And among gyms that restarted in-person classes last year? HIIT placed first.

In Seattle, more than two dozen studios offer HIIT sessions via ClassPass’s monthly subscription system, while others recruit newcomers entirely on their own. The training method’s rise is a years-long fitness trend across the country. But its flexibility has never been more valuable with work schedules and daily routines upended. Here’s why.


These workouts consist of a short warm-up, followed by several intervals in the “red zone”—80 to 90 percent of your maximum heart rate—with short periods of rest or low-intensity exercise in between. HIIT emphasizes efficiency; it can provide the same cardiovascular benefits and calorie burn as a steady-state jog or swim, in a shorter amount of time. Outdoors, reaching the red zone might involve sprints or cycling uphill. At home or in the gym, a variety of aerobic and resistance training exercises—high knees, burpees, mountain climbers—can get you there.

How Intense Is That “Intensity”?

Saman Kouretchian of fitness studio the Six in Westlake recommends starting with a 1:1 ratio—one minute at 80 to 90 percent of your max heart rate per one minute of recovery. As your fitness level increases, you’ll need less rest per interval, but that recovery time is key to receiving the full benefits.

Over time, getting your heart rate up to those sprints improves your VO2 max, a measure of fitness that recognizes the body’s ability to intake oxygen and produce carbon dioxide. The better your heart sprints, the longer it’ll be until you get too tired. Pairing HIIT workouts with resistance training—push-ups and squats, versus the pure cardio of jumping jacks or jump rope—helps build muscle and burn body fat efficiently too. Local brands like Sensoria and Wyze make wearables that can measure your maximum heart rate.

No Equipment Necessary (Until It Is)

The majority of HIIT workouts fit any setting because they use only bodyweight: lunges, squat jumps, straight-leg sit-ups, and many, many more. Still, NW Fitness Project in Fremont hands out sliders, kettlebells, and elastic bands to ratchet up the resistance for more intensive strength training.

Others get creative with objects around the house. Local practitioners have been known to fill a backpack with books and rice to power planks, or use a coffee table for tricep dips. Even those who go light on equipment might want to invest in a yoga mat and keep a sweat towel handy.

An Interval of HIIT History

Over a century ago, long-distance runners started using interval training—accelerating for 400 to 1,000 meters at a time—pioneered by the coach of Finnish Olympic gold medalists Hannes Kolehmainen and Paavo Nurmi. The first scientific publication on HIIT, however, didn’t come out until the 1960s. Follow-up studies over the next several decades expanded research to consider applications of strength training and anaerobic exercises. By the 2000s, HIIT had spread to sports like soccer and football and, eventually, gyms everywhere.

In Seattle, trainer Saman Kouretchian points to the arrival of Barry’s Bootcamp, an international fitness chain, next to Denny and Westlake as a sign of HIIT’s popularity in the Emerald City. Others cite the expansion of Barry’s competitors, Orangetheory or F45, and the growing density of boutique gyms offering this style of workout.

Ergonomic Edge

Jennifer Heap of Community Fitness in Roosevelt bases her brand of HIIT on building strength for simple, everyday postures: planks and push-ups to get your back out of that computer-facing C posture, and to strengthen wrists that have been typing all day.

The Top Digital Workouts of 2020

According to ClassPass.
➊ Yoga
➌ Pilates
➍ Barre
➎ Dance

Local Stream Celebs

With an infinity wall set up in their Seattle-area garage, years of training experience, and some relatable huffing and puffing, Daniel and Kelli Segars have built a virtual fitness empire from home. The couple behind Fitness Blender posts free workout videos on YouTube that have earned them more than 6.5 million subscribers. A wide range of HIIT workouts is core to those gains; a 36 percent increase in video views last year was driven in part by Daniel’s “Brutal HIIT Ladder Workout” and Kelli’s “Ultimate HIIT Workout for People Who Get Bored Easily.”

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