HRM vs Noom

christenwypy

I usually trust my Polar HRM but I also use Noom on my phone to track my miles when I walk/run. I put in that I am walking since I only run intermittently. What I usually do now is run as long as I can (maybe 2 minutes or so) and then I walk until my heart rate is down to 120-130 and then I run again. Anyway, I noticed today while running I glanced at my HRM and it said my heart rate was 55! I could feel it was more like 155 but it still scared and shocked me. My heart rate is not even 55 first thing when I wake up. It fixed itself after a minute or so and was 153. When I was done with my walk/run Noom said I burned 288 calories and my HRM says I burned 412. Since Noom thinks I am just walking I am assuming that is why this is lower. But with the other mishap, I want to be sure. Which would you trust?