Hands-on: Garmin Vivosmart 4, now with Pulse Ox and Body Battery | DC Rainmaker
Garmin Vivosmart 4 review: Garmin's new ultraslim Vivosmart 4 gets more features, easier to use - CNET
The validity of activity trackers is affected by walking speed: the criterion validity of Garmin Vivosmart® HR and StepWatch™ 3 for measuring steps at various walking speeds under controlled conditions [PeerJ]