It’s nearly impossible to count all of the fitness trackers on the market; there are ones tailored for hard-core runners, stylish designs pegged for women, even ones that alert you when you've been in the sun for too long. But there’s never quite been one developed specifically for those in manual wheelchairs before.

Last month, Apple announced on stage at its annual Worldwide Developers Conference that it was adding a way for wheelchair users to monitor their activity levels, mostly powered by upper body strength used to move the wheels.

The move is a part of the company’s effort to turn the Apple Watch into the first wheelchair-accessible wearable. The device will track pushes, rather than steps, and encourages users to meet daily goals, burn more calories and nudges them to keep moving throughout the day. For the 2.2 million people who use manual wheelchairs, staying active each day is extremely important to reduce greater health risks such as diabetes or a stroke.

Starting this fall, watchOS 3’s Activity app experience will be optimized for wheelchair users. The software will still include Apple's signature three-ring tracker that highlights how close you are to hitting daily goals. Pushes from wheelchair users wearing the Apple Watch will contribute to all-day calorie goals ( the red ring) and instead of a “time to stand” reminder (the blue ring), wheelchair users will receive a “time to roll” notification. Apple is also adding a collection of dedicated wheelchair-specific workouts -- exercise information will be logged via the green ring with a goal of 30 minutes each day. 

Meanwhile, the Workout App will have two additional options: Wheelchair Run and Wheelchair Walk. All data is accumulated with Apple’s Health app, similar to what happens for Apple Watch users running its standard mode. 

When the company sought to add a wheelchair tracking mode to the Apple Watch as early as version one in 2015, it didn’t realize what a massive challenge adding those features would be to the platform. Apple's Ron Huang, director of software engineering for location and motion technologies, told Mashablethe complications stemmed from the limited amount of fitness research that’s been conducted among wheelchair users in the past.

As a result, the company started from the ground up to gather information and develop algorithms that could accurately measure pushes and fitness metrics on the Apple Watch. To conduct the research, Apple partnered with San Diego-based Challenged Athletes Foundation to monitor more than 3,500 hours from 300 people (across 700 sessions) about how they responded to the technology.

Apple also worked alongside the Lakeshore Foundation, which closely follows the long-term physical and emotional effects of physical fitness on people with disabilities. Its facilities have also served as the official U.S. Olympic & Paralympic Training Site and is the official home of USA Wheelchair Rugby since 2003.

The teams loaded sensors, accelerometers and GPS technology onto wheelchairs to monitor distance and speed.

The teams loaded sensors, accelerometers and GPS technology onto wheelchairs during the study period which were later used to monitor distance, speed and how much they were using their arms.

Apple studied three wheelchair push styles -- semi-circular, arc and single loop over -- to determine how it impacted fitness and were different as users when up or downhill. With the help of VO2 masks, it also measured how much oxygen they were using throughout the duration. 

When the features debut in the fall, it will join an abundance of new additions and an overall refreshed look. WatchOS 3 will become more like the iPhone, with the ability to swipe up from the bottom of the watch for a control panel, a dock with most-used apps and several strategic changes. For example, you'll only be able to access the app bubbles cluster when you press the digital crown.

Apple is also giving more attention to its health and fitness capabilities, which it calls the most used features on the Apple Watch, with more screen space and new features. Emphasizing its greater commitment to health in general, the company most recently announced iPhone users can register as organ, eye and tissue donors on the National Donate Life Registry, right from the Health app.

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