Orangetheory Fitness’ new location, which has been under construction at 25 Hudson in the former Ninja space just south of Duane since last September, is coming together. Starting this month they are holding classes for the “founding members;” the official opening will be in early October. (There is absolutely no remnant of Ninja — it’s impossible to imagine the space as a spooky theme restaurant.)

It looks ready to go to me! This studio — it’s a franchise — has room for 16 people at each of three stations. So a class can run with as many as 48, with each group leaving its station and moving to a different one every 20 minutes or so. This is the biggest studio in Manhattan.

In addition to the one workout room, the gym has five stall showers and four stall bathrooms — all gender neutral — plus a mirrored dressing room with several seats and hair dryers.

The workout is interval training designed to keep your heart rate in what they call the “orange” zone, higher than baseline but not all-out. They do that with coaching on each of the three stations: treadmill, rowing machine and a bench with access to free weights, a bosu ball and resistance bands. (They have a couple of bikes and elliptical machines for people with an specific issue and can’t use a treadmill,) Members wear a heartrate monitor and log in at each station; their vitals are displayed on a screen in front of them at each machine. Stats are collected after each workout, so you can check your progress on an app.

“Our job as coaches is to push people to get their heart rate into 85-91 percent,” said Erica Kennedy, a coach for this location. “That’s what makes us so close to personal training. Everyone’s push can be individualized. We can look at your average speeds or inclines over time. That allows you to instantly challenge yourself at each workout, and coaches can look at data and help clients reach their goals.”

The franchisee, Empire Portfolio Group, has seven other Orangetheorys in Manhattan as well as another 130+ locations on the East Coast. The Fidi location on William is run by a different group; the Soho location is independent.

Orangetheory itself was founded in 2010 in Fort Lauderdale by physiologist Ellen Latham, a highly trained physiologist whose first designed what she calls The Ultimate Workout. That evolved into Orangetheory, which now has more than 1500 locations worldwide.