Last night I did my first workout with my Apple Watch. It was a DailyBurn which would be similar to a P90X style workout. Looking at the data in the Health app my HR there are some moments where the data would stay in the 150-106's then drop back down to the 40-60's. I keep the watch snug on my wrist but did notice during some of the punching parts the green glow of the sensor was visible. Am I not wearing my watch tight enough or does movements prevent an accurate reading?