It was only a matter of time before wearables entered the group fitness world. While you won’t find tons of classes using fitness trackers yet, one studio is daring to give it a shot. Enter SweatBox, a new boutique fitness studio in Washington, D.C. I tried it to see how tracking my heart rate and power affected my workout.
WHAT IS SWEATBOX?
SweatBox is basically a 50-minute workout that uses heart-rate training and high-intensity intervals to whip its students in shape. You’ll switch quickly between 6–8-minute strength circuits working every muscle group and 3–6-minute high-intensity cardio circuits and active recovery sessions on spin bikes. The class sizes are small — mine had 5 students — so that the SweatBoss (their term for “instructor”) can offer personal attention to each person.
Before co-creating the programs at SweatBox, Isiah Munoz, who’s also SweatBox studio manager and trainer, tried different interval-based classes in New York and the D.C. area to suss out the market. “Many places advertise that they offer interval training when in fact they have their clients at a steady 80%-plus of their max heart rate for the entire class,” he explains. “This is not an interval; this is aerobic or excessive anaerobic training. Intervals require bursts of super-intense work followed by recovery.
The American College of Sport Medicine defines high-intensity interval training as “repeated bouts of high-intensity effort,” often at 80–95% of your maximum heart rate, “followed by varied recovery times.” Your heart rate is supposed to dip down in these recovery times. Like many people, I didn’t even realize I was doing interval workouts wrong by failing to vary my exertion level.
READ MORE > HEART RATE MONITORING BASICS
The bikes are the Matrix IC7 Coach by Color, which calculate your functional threshold wattage based on your age, weight and frequency of working out. Your FTW is fitness-speak for the max amount of power you produce over time (typically an hour) when pedalling on your bike. The bike has color-coded effort levels that help instructors see your intensity.
For the workout circuit, each student has their own area stocked with dumbbells (the lightest was 12.5 pounds, instead of the lighter 2 pounds at other bar and spin classes I’ve taken), XT trainers and a mat. Your FTW and heartbeat are displayed for all to see on the big screens on the walls — which, along with the bike’s color-coded effort levels — help instructors get a sense of how hard people are working at a glance.
HOW DID MY CLASS GO?
We started on the bikes, which are programmed to determine our individualized exertion levels by displaying colored lights that also flash on the leaderboards next to our names. This totally brought out my competitive side — and it made me push even harder to match or beat my sister, whom I pressured into coming.
With only five students, our instructor gave me tons of one-on-one attention, telling me to speed up when I was not keeping pace. (“Get in the green!” she shouted, pushing me to dial up the intensity.) At one point, she even surprised me by telling me to slow down, as I was exerting too much during my recovery.
After a few grueling minutes on the bike, it was time to switch things up. We moved to the floor, doing a series of exercises with our body weight. I started seriously regretting my lunch when I held that first plank. Then came lunges with resistance bands, then we planked again, with both feet hooked into the resistance band this time. At that point, I was shaking like a sweaty pendulum as I hovered above the floor and struggled to find my balance.
As soon as I started to get exhausted — or accustomed to — the workout circuit, we moved to the next surprise circuit. At the time, it didn’t feel like the happy kind of surprise. At one point, we were doing squat jumps on and off the raised platform, and my legs felt ready to give out. Of course I was in the red zone — maxed out. But we were not done yet, because then we did partner workout where I did a variation of burpees while my sister held planks until I was done. At that point, I was toast. But being accountable to my sister prompted me to hustle out of some sort of older sibling obligation — a tactic that turned out to work for me.
THE SWEATBOX FACTOR
“By monitoring every minute and second of our program in real-time, we can ensure that our clients have peaks and valleys during the entire workout,” says Munoz. The key to SweatBox is individualization: “I don’t want to put 23 people in a room and have them do what I’m doing, at my tempo, at my pace,” says Munoz. Instead, he wants to give people the tools to “quantify their own output and then make active decisions about when they need to work harder and when they want to recover.”
Munoz encouraged us to switch things up by integrating different interval sequences each time, and he stresses the importance of combining strength and cardio training in the same session: “If you just do cardio or just take a cycle class, you’re not going to burn as many fat calories all day, and during that class, as when you combine strength training and cardio,” he says.
His workout advice is grounded in science. According to a 2011 study in the Journal of Obesity, when you do aerobic workouts at a constant exertion level, the effect on body fat is “negligible.” But embracing a “high-intensity intermittent exercise routine” — which can feature high energy bursts on a spin bike, followed by lower-energy exercises like planks and short periods of rest — “may be more effective at reducing subcutaneous and abdominal body fat than other types of exercise.”
For the competitive among us, hitting your target numbers can be a reward in itself. After class, I checked in with Munoz to see if the quantified effort level I saw on the screen at the end of class — 84% of my max — is what I should have been aiming for.
“That’s high. That’s good,” he says, making my inner nerd swell with pride as if I just aced a major exam.
GEAR UP FOR YOUR NEXT WORKOUT