Palpitations with a burst of fast heart beats while blowing up pool float. happens right after i stop blowing. thought this was suppose to slow hr?

Normal response: Not sure where you got that information. As we expend energy in any form we require increased blood flow, to in this case the chest wall muscles and diaphragm, to keep them fed and oxygenated. One of the ways our body does this is by increasing the heart rate just like it does if you start running or perform any other activity, even digesting food expends energy.