A 1% error in approximating a second by a heartbeat will cause an approx 4hz error in the frequency. Here's a chart of the distribution of heartrates found in

A 1% error in approximating a second by a heartbeat will cause an approx 4hz error in the frequency. Here's a chart of the distribution of heartrates found in random middle-aged people measured over 24hours: https://d1ieb9vw5zjdt6.cloudfront.net/content/europace/7/2/104/F1.large.jpg https://d1ieb9vw5zjdt6.cloudfront.net/content/europace/7/2/1... Source: http://europace.oxfordjournals.org/content/7/2/104 http://europace.oxfordjournals.org/content/7/2/104