In regards to comments about the chest strap and heart rate, it depends on the strap condition, the battery in the transmitter and then finally your watch. Lots of variables. The calories burned that are suggested on programs, cardio machines , etc. are averages which can either be encouraging or completely the opposite. Just remember they are based on algorithms and we are all different for so many reasons. If you are cardio-fit and trained, the numbers are going to be lower and the more fit you are the lower the heart rate and calorie burn. Also depends on other variables such as age and sex and how you feel, overfed, starving, hot, cold, etc. Not to mention sports watches...holy cow! I've had 7 different multi-sport watches in the past 10 years, including the latest Apple Watch Series 5 this past December (took it back for several reasons). The latest Polar offering (Vantage Series) which I also returned. I have had a few Garmins and a Suunto . I'm currently using a Polar V800, probably the most popular multi-sport watch ever. Anyway, that watch is so accurate, I bought 3 more, yup, that good, and because they don't make them anymore...replaced with the Vantage series, which needs a lot of work. Wearing that watch with a clean strap and transmitter with a solid battery is the holy grail. The only way to realize that is having used several watches and knowing yourself completely. I've been a sport racer for years, and we all talk about this very subject, but it comes down to knowing the way we feel, I'm pretty sure I don't even need to wear a watch anymore and I have accurately compared rides with and without a sports watch. The reason why I wear the V800 is it has the most sublime way of telling me when I'm overtraining and I follow that explicitly. Probably all sounds way to serious and technical, unfortunately, there is quite a bunch of crap on the market and over-hyped products with color screens and streaming music and a billion apps that have nothing to do with the main goal. I would stick to the basics. I still will buy a lower end Polar versus the top other 3 because of their algorithm models. Just keep the strap clean, and when you get dicier numbers, change the battery in the transmitter and/or get a new strap.