Meredith Dietz Meredith Dietz Senior Staff Writer Experience Meredith is a marathon runner and stand-up comedian. As Lifehacker’s Senior Staff Writer, she covers personal fitness tech, home gym equipment, and more. Read Full Bio April 20, 2026 Add as a preferred source on Google Add as a preferred source on Google We may earn a commission from links on this page. Credit: EF Stock / Shutterstock Table of Contents I spent the last month testing and reviewing the Garmin Forerunner 970 , and my biggest disappointment (one of only a few) was that I couldn't use it to test my running economy, since it requires a heart rate monitor like Garmin's HRM-600 chest strap . At the same time, it does lend a lot of legitimacy to Garmin's running economy metric, knowing it requires key inputs like heart rate, stride length, ground contract time, vertical oscillation, and step speed loss. "Running economy" has a lot of buzz around it right now.…