Few things are tracked as fastidiously as fitness. From beats-per-minute to miles-per-minute, winning, it seems, is all in metrics these days. But you needn’t be a mathlete to compete with the fitness hipsters. Thanks to technological leaps and fashion bounds, it’s now easy to muscle in on a numerical advantage yourself.

And thank the tech gods for that. Gone is that weird guy in the gym with a heart rate monitor strapped to his chest like some sort of disco Terminator. Now all you need to view almost every marker of exertion is a cursory glance at the wrist. But the question that boggles runners and gym bros alike remains: what to watch out for when buying a fitness watch?

Simple, says Kerry McCarthy, gear editor at Runner’s World magazine. There are some fundamental requirements that make for a good fitness timepiece; you need those and nothing else. Here’s his list of essential tracking metrics, with tips on putting the stats to use.

The Stats You Need To Know

Stride Length

“Mo Farah gobbles up around 2m of ground with every stride thanks to his long legs and super-flexible hips. Yours is likely to be less than half of that, but you should be aiming for between 1-1.3m with each stride. Shorter and it means you’re scuttling (and thus wasting energy); longer and it means unless you’re also a yogi you’re probably over-reaching, which can lead to injury.”

Cadence

“Here’s one elite habit you can aspire to. All the top runners take around 180 strides per minutes, which is seen as optimal. If you’ve never paid any attention to it, it’s more likely yours is currently around 160. Work on turning your feet over a little quicker to make yourself the most efficient runner you can be.”

Heart Rate

“There are numerous online algorithms to help you work out your own target maximum heart rate but the old formula of 220 minus your age is still a more than adequate guide for beginners. So if you’re 45 years old your maximum heart rate should be 175. And that’s when you’re eyeballs out. For easy to steady runs you should be somewhere around 50-60 percent of your maximum.”