The standard formula for calculating one's maximum heart rate is "220 minus your age". But experts suggest the textbook is wrong: everyone's maximums, from heart rate to output, are different. Understanding yours is the key to peak performance.
To learn how to unlock my potential for next year's Standard Chartered Hong Kong Marathon, I meet Dr Michael Tse from the Active Health Clinic and University of Hong Kong's Institute of Human Performance. Tse is a former trainer and performance consultant to many of the territory's elite athletes.
A number of factors make a great runner, he says, including body composition, running mechanics and strength. "But when you're starting out, what you really want to know to become a faster, more economical distance runner, is how to benchmark your fitness. Doing so allows you to see your inherent ability, as well as what sort of training will help you."
There are two measurements that are key, says Tse. First, VO2 max, or the maximum capacity of your body to transport and utilise oxygen to fuel muscle movement. (Think of it as the size of your "engine".) Second, the lactate threshold, which is the point where pushing yourself harder becomes counterproductive during a long-distance race.
Knowing your VO2 max gives you a good indicator of your condition and shows you where you can push the boundaries of your training to improve.
Next, as running intensity increases, you produce lactate in the blood. Lactate (or more accurately, its negative by-product) is responsible for that burning sensation in your legs when running. While the good news is your body is pretty effective at processing lactate, there's a point where its production exceeds its removal: the "lactate threshold". It's the point where fatigue sets in.