Heart rate is typically used to measure the intensity of training, with runs often being prescribed as sticking to a particular heart rate zone to gauge one’s effort. However, in order to get the most out of it, you need to know the factors that might influence the readings so that you can interpret the data in a meaningful way.
Some of the following are factors that might influence your heart rate:
- Certain factors tend to increase heart rate readings at sub maximal intensities – these include heat, altitude, caffeine, a lack of sleep, an increase in stress, dehydration, sickness and many others.
- The time of day will have an effect on your heart rate. Typically, one’s resting heart rate will peak in the late afternoon / early evening
- Higher levels of fatigue will elevate your heart rate at sub-max intensities / rest, but may prevent you from reaching max HR
- Younger athletes will have a higher max heart rate
- Low glycogen levels will lower your max heart rate – which is why your HR may actually dip towards the end of a marathon
- Equipment readings are not entirely accurate; particularly when using wrist-based heart rate monitors. These readings are also influenced by factors such as moisture and the positioning of the strap on your wrist/body.
Typically, people focus too much on the specific numbers and exact readings, when in reality a small factor can have a pretty big influence on readings. Once we also factor in a degree of imprecision in our heart rate measurement tools, it’s clear that HR needs to be used with a degree of caution as a training tool.
With this in mind, HR data on its own is not entirely useful. However, when combined with other performance markers, resting and exercise HR are very useful variables.