The Cupertino-based company continues to assess the utility of the Apple Watch band as a location for medical sensors.
The studies will be conducted in collaboration with leading medical institutions to examine hearing, women's, mobility and heart health.
The best smartwatch in the world just got better with a slew of new features that will help Apple cement its position at the top of the market.
Tension has been increasing within the team in recent months, according to eight people familiar with the situation.
The early-stage study took place over 12 weeks and included an 82-person healthy control group and 31 individuals with varying stages of cognitive decline.
New capabilities include women cycle tracking, Noise app, Activity Trends and App Store right on the wrist; also, there are new watch faces.
The Cupertino-based company has a few key advantages over its technology rivals, including privacy and the huge base of iPhone and Apple Watch users.
Such technology would enable owners of future iPhones and Apple Watches to detect things like spoiled food, body odor and perhaps even blood sugar levels.
Part of the watchOS 5.2 update, the ECG app can capture heart rhythm in a moment when users experience symptoms such as a rapid or skipped heart beat.
The largest study ever of its kind enrolled over 400,000 participants from all 50 states in a span of only eight months.