I'm addicted to a boot camp-style workout that's taking over America -- here's what it's like

Orange Theory studioOrange Theory FitnessOrange Theory Fitness classes focus on high-intensity interval training.

If you haven’t tried Orange Theory Fitness, it’s likely you know someone who has.

The boutique fitness franchise now has 728 studios in 16 countries and is in 45 states in the US.

The company, which was named the fastest-growing woman-owned company in 2017 by Forbes, brought in $US451 million in revenue last year.

I’ve been going to Orange Theory for about eight months now, and I’m totally hooked. Its 60-minute classes leave me feeling like I’ve given my all, and I’ve gotten a lot stronger since I started going.

Here’s everything you need to know about the fitness company that’s popping up everywhere across the US.¬†

Orange Theory's group workout classes are 60 minutes long and focus on high-intensity interval training. In each class, you'll cycle through workouts on a treadmill, on a rower, and on the floor.

Source: YouTube

Each class has a distinct focus. Endurance classes feature long stretches on the treadmill and high rep counts on the floor. Strength classes have a lot of uphill climbs on the treadmill and heavy weights on the floor. In power classes, you'll work on speed.

The class is generally broken up into two groups. One starts on the treadmill, and one starts on the floor and rowers.

Source: YouTube

You'll spend about 28 minutes on the treadmill. The instructor will guide you through the workout, calling out when to increase or decrease your speed and incline. I run about three miles in each class.

Before I started Orange Theory, I hated running. But the running portion of the class has made me a much more confident runner, even though it leaves me breathless. You can choose to ride a stationary bike or strider if running really isn't your thing.

The other half of the class is spent on rowers and on the floor, where you'll do everything from lifting weights to push-ups.

Everyone in the class wears a heart rate monitor so you can keep track of exactly how hard you're working at any given time.

Orange Theory Fitness

Screens throughout the studio display your heart rate.

Source: YouTube

Orange Theory breaks heart rates down into five colour-coded zones that range from grey -- 50-60% of your maximum heart rate -- to red, or 92-100%. The goal is to spend as much time in the orange and red zones as possible.

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Every class at Orange Theory is different, and studios don't advertise what the focus of each day's workout will be beforehand.

However, there's an active Orange Theory community on Reddit where workouts are posted. Every studio generally follows the same workout routine each day, so you can be doing the same workout as someone across the globe.

After each class, you get a summary of how you did. Splat points refer to the number of minutes spent in the orange and red heart rate zones, or anything above 84% of your maximum heart rate.

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Orange Theory instructors say that if you spend 12 or more minutes in these top heart-rate zones, it produces an 'after-burn' effect, which causes your body to burn more calories in the 24-36 hours following your workout.

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Classes aren't cheap. At the studio I go to in Brooklyn, a single drop-in class costs $32, and a 10-pack costs $290, though prices vary across the country. For comparison, a 45-minute class at SoulCycle in New York City costs $34.

Alli Harvey / Stringer / Getty Images

Orange Theory, which was founded in Fort Lauderdale, Florida in 2010, is expanding rapidly. It's on track to have 900 studios by the end of 2017.

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As of last month, the company had a little over 526,000 members, up from 439,000 in 2016. Revenue was $451 million last year.

Orange Theory Fitness

I've tried a ton of trendy workouts from spinning to barre, but nothing gives me as good of a workout as Orange Theory does. I have many friends who say the same.

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I try to go to Orange Theory about twice a week and do other exercises like pilates and barre the rest of the week. My hope is that Orange Theory keeps me motivated and that I don't get tired of it like I do with most other fitness classes.

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