OK, we agree...that's why people who are experts and very practiced in their fields often report that UNDER PRESSURE their heartbeat slows down. It's very difficult for a person who experiencing adrenaline spikes and erratic heartbeats to be PRECISE with their movements. So often "everything slows down"... but most often it's due to how the mind is remembering the moment and how detailed the recording of that moment is in the brain. The brain is on fire, but the heartbeats are smooth and easy. Again, not everytime, but that's what experts marksmen and others report.