Orangetheory Fitness classes focus on high-intensity interval training. Orange Theory Fitness If you haven't tried Orangetheory 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 $451 million in revenue last year.

I've been going to Orangetheory 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.