Measuring heart rate while swimming

My heart rate reaches one peak just before getting on the block, and a second just before entering the warmdown pool. Heart rate while swimming could be deceptive. I read a scholarly paper (long time ago, no links, sorry) that said people's heart rates are much slower in water than doing the equivalent level of exercise on land. They said it wasn't clear why but the slow-down was extreme enough that aerobic levels of exercise did not have typical aerobic heart rates. I did google research on the topic and this was the first result: “hydrostatic (water) pressure pushes blood out to the extremities, and in combination with more supple blood vessels, stroke volume and cardiac output increases. This means that the heart becomes more efficient, pumping more blood. With this kind of blood flow, heart ratecan be lowered”

My heart rate reaches one peak just before getting on the block, and a second just before entering the warmdown pool. Heart rate while swimming could be deceptive. I read a scholarly paper (long time ago, no links, sorry) that said people's heart rates are much slower in water than doing the equivalent level of exercise on land. They said it wasn't clear why but the slow-down was extreme enough that aerobic levels of exercise did not have typical aerobic heart rates. I did google research on the topic and this was the first result: “hydrostatic (water) pressure pushes blood out to the extremities, and in combination with more supple blood vessels, stroke volume and cardiac output increases. This means that the heart becomes more efficient, pumping more blood. With this kind of blood flow, heart ratecan be lowered”