Heart rate training can be very useful for runners hoping to train more effectively by helping us to avoid those dreaded junk miles. Heart rate monitors can be purchased as chest straps and some GPS watches now even have built-in optical sensors on the wrist.

Since I’ve been training with heart-rate for quite a few years myself, and as an ambassador for Suunto, I often get asked about training with heart-rate. I’ve also realized in talking with people that there’s quite a bit of confusion on how heart rate can and can’t be used.

Here are 5 common mistakes that runners make when training with heart rate.