As Apple continues to build up hype for the upcoming Watch launch on April 24th, the company has given ABC News an exclusive look at the health and fitness lab used for developing the activity features for the new wearable. Jeff Williams, who introduced ResearchKit on stage earlier this month, is featured in the video interview discussing the Apple Watch’s potential impact on health, while Jay Blahnik, formerly of Nike, leads a tour inside Apple’s fitness test facility.

Williams says that Apple employees including engineers and managers have volunteered to perform a wide range of workout activities including “rowing, running, yoga” and more at the high-tech lab in order to testing the fitness functionalities of the Apple Watch. Employees volunteering to be a part of the fitness data collection activities were not briefed on the Apple Watch device specifics ahead of last September’s reveal, Williams adds.

In the video, Jay Blahnik walks through a brief tour of the advanced fitness facility,  which he says includes climate chambers. The lab can simulate various environments that Apple Watch wearers might be in during workout activities, although Blahnik adds that the Watch was tested in locations ranging from Alaska to Dubai as well.

“[The employees] knew they were testing something, but they didn’t know it was for the Apple Watch,” said Jeff Williams, Apple’s senior vice president of operations. “We hooked them up with all the masks and so forth, but we would put on an Apple Watch covered up.”

You can see the Apple Watch fitness development lab below, and ABC News says the full story will be featured on Nightline tonight at 12:35 AM EST:

[youtube https://www.youtube.com/watch?v=LsgOmiStJ04]

(Update: ABC News removed the video from YouTube, but you can catch the video here in the United States for now.)

In terms of fitness features, each model of the Apple Watch including the Sport and Edition collections features a custom heart rate sensor for measuring intensity of workouts and an accelerometer for collecting movement data while using WiFi+GPS from the iPhone for capturing speed and distance during activities.

The Apple Watch pre-order kicks off April 10th when the new device will be able to preview in Apple Stores. Two weeks later, the Apple Watch will begin shipping in 9 countries on April 24th with prices ranging from $349 to $17,000.