Heart rate

Your heart rate (or pulse) is the number of heartbeats per minute. It tells you two things: at rest, how fit your heart is, and during exercise, how demanding an activity really is at that moment.

In adults, resting heart rate is usually between 60 and 80 beats per minute; in children it's higher (often 70 to 110 in primary school children). Measure it in the morning before you get up. Regular endurance training often lowers it by five to ten beats, because the heart pumps more blood with each beat. A resting heart rate that is clearly above your normal value for several days is a sign of an infection, stress or not enough recovery.

To gauge your training intensity, you need your maximum heart rate. The well-known rule of thumb of 220 minus your age (Fox, 1971) is simple but inaccurate – the actual deviation is a good ten beats either way. The Tanaka formula (2001) is somewhat more accurate: 208 minus 0.7 × age. For a 40-year-old, that comes to around 180. Neither formula applies to children; their maximum heart rate is usually around 195 to 205, regardless of age.

This gives you training zones: 60 to 70% of your maximum heart rate for easy base training, 70 to 80% for brisk endurance work, and over 85% for short, intense intervals. If you don't have a heart rate monitor, use the talk test: full sentences = easy, short sentences = moderate, single words = intense.

Important for people with high blood pressure, heart disease or on medication such as beta blockers (which lower the heart rate): these formulas don't apply, and a medical check-up before you start is a must. The same goes for anyone over 45 who wants to get back into sport after a long break.