You may have heard of pace per mile or VO2 Max as guides for how fast you should run. Heart rate when running is also a great tool to use to determine how hard you should be working during a run or workout. Most sports training programmes use the following variables: frequency, duration and intensity. It’s under intensity where heart rate training comes in. But if you’re confused about your heart rate and how it should be used during your training, this guide has got you covered!