Polar, the longtime makers of heartrate-monitoring watches and chest straps, has launched a Bluetooth Smart-enabled, iPhone-connected activity tracker. The Polar Stride Sensor Bluetooth Smart is a small device that clips to the shoe and tracks stride-length, speed, running cadence, and distance.

Activity tracker maker Fitbit notably uses Bluetooth Smart in its devices, but while Fitbit is geared at tracking all-day, every-day movement, Polar is catering to the the dedicated runner crowd, tracking indicators that the company calls "intelligent training data."

The data collects can be accessed via an iPhone 4S, iPhone 5, iPod touch, iPad and iPad mini, or any Bluetooth SmartReady device, according to the product page. On an iPhone, it's compatible with Polar's training app called Polar Beat. Polar Beat recently added a "smart coaching" feature that helps runners improve their efficiency from run to run. Polar also has a free personal training website.

The device is water- and shock-resistant and tracks speed and distance without using a GPS, which both reduces power requirements and also allows it to function in indoor or remote areas areas without a strong data signal. The device costs $79.99.

Polar launched its original s3+ stride sensor in the fall of 2006, but it is only compatible with particular Polar sports watches. Polar also launched a Bluetooth Smart chest strap heartrate sensor, the H7, in June 2012.

When Bluetooth SIG chief marketing officer Suke Jawanda spoke to MobiHealthNews about the technology in April, he cited the H7 as an example of how impactful the low energy consumption can be.

"Polar created a Bluetooth heart rate monitor," Jawanda said at the time. "Under normal use cases, the coin cell battery that was powering that heart rate monitor would only last a few months. That same heart rate chest strap now, with Bluetooth Smart, is going to last a couple of years."

At the time, IMS research projected that by 2016 more consumer medical devices would use Bluetooth Smart for wireless than any other technology. Last week, ON World released a report on sports and fitness trackers, predicting that 500 million mobile fitness and health sensors will ship in 2017, with two-thirds for activity tracking.