#1 The sweat and heavy breathing (or lack of it) are a sign of effort, but how hard you’re working out is objectively gauged by measuring your heart’s beats per minute.
#2 BPM is the basic unit of measurement for heart-rate training, i.e. keeping your heart rate within a certain range or zone of BPM during your workout. This zone is usually based on a percentage of your maximum heart rate.
#3 By keeping your heart rate in certain recommended zones, you’re supposedly exerting enough effort to optimise your workout’s effectiveness. The recommended zones can be personalised to take into account not just age, gender and fitness level, but also environmental conditions and your current energy levels.
#4 Get started! First, know your max heart rate. There are many ways to calculate this, but those that rely on age and gender alone are of limited use because they rely on averages. Some of us are built for endurance (lower max heart rate), and others, for speed (higher).
One way of calculating your max heart rate is to subtract your age from 220. If you’re 30, this would be 220-30=190 bpm. From here, you calculate your target heart rate for your workout by deducting your resting heart rate from your max heart rate. Your target heart rate is a percentage of this figure, e.g. 60%, as recommended by your trainer depending on your workout goals. Complicated? No fear, your trainer is there to help.
#6 Only after doing #5, then invest a good heart-rate monitor for training. Be wary of optical wrist-based trackers; research shows they’re inaccurate.
#7 Your resting heart rate is a great measure of how much fitter you’re becoming whether you’re on an aerobic or muscle-building workout plan. The lower it gets, the fitter you generally are. If it goes up instead, you might be overtraining or OD’ing on caffeine. Bear in mind that it will take a while before you get to 60 BPM and below, like pro athletes. The point is to observe whether it trends upwards or downwards.
#8 So you’ve now got a bunch of data and they seem rather alarming/encouraging. Don’t try to be a human fitness algorithm and interpret them yourself. Google’s not your best friend here. It’s your trainer.