Review on Coros Performance Optimization Efficiency Strength by Nick Reddy

I bought this product to train for an ultramarathon. The COROS pod attaches to the back of the running tights, mid-waist, to provide accurate information on stride length, size, power and efficiency. You need to download the app on your smartphone and keep it running while running. There are 3 reasons why I would not recommend this product. 1) It drains your phone's battery faster than other apps. It drained my phone battery so much it drained my phone battery in about 4 hours. If your phone turns off while running, no part of the run will be recorded and all information about that run will be lost. 2) The friction of the capsule when running will cause chafing after 5-6 miles. On longer runs, it rubs until it bleeds. 3) It doesn't track mileage accurately. At first it showed fewer kilometers than I ran. (I rode the route and mentally marked every kilometer.) It was always about 20% lower. Lately it turns out that I have driven more kilometers than I actually have. This morning I ran exactly 7 miles. The COROS module documented a run of 7.74 miles. Because mileage isn't accurate, pace per mile isn't accurate either. It makes me think that efficiency, power, walking speed. can also be inaccurate. I would not recommend this product for long distance runners.