Heart rate and cancer
Your heart rate is easy to measure reliably, non-invasively, and without using anything more technically advanced than a watch with a second hand.
It’s a good indicator of physical fitness and general health, and predictive of mortality not only from heart disease, which you might expect, but also from cancers such as those of the breast, colon, and lung cancer.
The relationship between heart rate and these cancers is as strong as the correlation with heart disease.
A difference in heart rate of 10 beats per minute is equivalent to a 10% to 20% difference in mortality.