(Image credit: Future)

Easy runs, otherwise known as zone 2 training , are having a moment. I mean, it has always existed, but as more and more people take on serious training plans ahead of half marathons, marathons, or even ultramarathons, preparation is key. And as any running coach will tell you, easy runs should feel easy.

If you're guilty of negative splits (your pace getting quicker as your run progresses), you could run the risk of overtraining and getting injured before you reach the start line.

Zone 2 refers to around 60-70% of your maximum heart rate, where you tap into fat for fuel. Training in this zone helps your body to become more efficient and producing energy without generating heaps of lactic acid. In short, you won't need days of recovery after these types of runs.

But if you're wearing a Coros Pace 4 and you're not sure how to tell whether you're in the correct heart rate zone, this quick how-to will help you set yours up.

On a scale of 1-10, Zone 2 should feel like a 3/4 out of 10.…