S4 sensors combined with S Health software enable handsets to be used to track exercise, eating, heart rate and other fitness factors.
The handsets were also designed to measure temperature and humidity to help people “understand what is going on around them.”
Samsung also took aim at the trend of people using their own smartphones for work with the addition of new Knox software that builds a secure wall between personal and business data on handsets.
“The Samsung Galaxy S4 is very good, but looks like an evolution to the S3, not a revolution,” technology analyst Jeff Kagan said.
Apple, which is known for keeping its plans private, is believed to be working on its own upgrades, including a new version of the iconic iPhone. However, Apple shares have slumped some 40 percent from highs hit last year.