Heart rate monitoring is especially useful in low-intensity runs. The reason is that, unlike pace, heart rate is not a performance metric. Runners don’t instinctively push to achieve higher heart rates that they can boast about the way they often push to achieve faster split times. When runners are given a heart rate “ceiling” to stay below, they usually have no trouble respecting it. But when they are given a pace target, they often try to beat it.
