[dsjoerg]

Can you offer a reference for this claim?

Here's a counter-claim: "A normal resting heart rate for adults ranges from 60 to 100 beats a minute.

Generally, a lower heart rate at rest implies more efficient heart function and better cardiovascular fitness. For example, a well-trained athlete might have a normal resting heart rate closer to 40 beats a minute."

Source: Mayo Clinic, http://www.mayoclinic.org/healthy-living/fitness/expert-answ...