Why running with a heart rate monitor will improve your performances and detect the likelihood of injury.

Words: Damian Hall

“Running without a heart rate monitor (HRM) is a bit like driving a car without a speedometer,” says running coach Marcus Scotney. “You’ll be getting stopped by the police regularly, because you’re over the speed limit. Forced to guess, you thought you were going slow enough. But really it was too fast and you have another three points. Or, rather, an injury and a three week rest before you should run again.”

There are reams of gadgets around now which include HRM. But while fitness trackers, GPS watches, smartphone apps and even earphones can record your beating heart, they don’t tell runners how to best use the instantaneous data to improve performance.

In fact, with the Strava culture of constantly striving to set segment records and beat mates to become King of the Mountain, heart rate technology could be doing runners more harm than good. “I think a lot people believe that to become a better or faster runner they have to always be running fast and hard – at tempo pace or anaerobically,” says Marcus. “Training constantly at tempo pace leads to injuries. The body isn’t getting the opportunity to rest and develop aerobically.” Only data from our heart rate can reliably tell us how hard we’re working. If we rely on guesswork, numerous factors influence our estimations: the wind might be blowing directly at us, it’s muddier than usual, our pack’s heavier than normal on a run commute, perhaps we’re tired (from all that tempo running). Those instances and others conspire to give us false information about how hard we’re running. “With a HRM, you can clearly see how hard you are working when running,” says Marcus. “A HR monitor will show you that. And show when we we’re in danger of overtraining.”

Marathon Training

But how do you use a HRM to improve your running? According to the popular periodisation model for a marathon training programme, runners concentrate on building base endurance first. Which means lots of easy runs. “This strengthens the muscles,” says Marcus, “increases muscle capillaries and mitochondria (the power houses in our muscles). We recover quicker from easy, low-HR runs as well, meaning we aren’t tired for several days post-long run.” A HRM is a great way to ensure the easy runs really are easy, all below a runner’s lactic turnpoint. “After about six weeks of low HR training, the runner would introduce a mixture of higher HR training (in HR zones 3-5) to improve speed and stamina.” Each training run would be done in a specific heart rate zone – there are usually between one and five zones stipulated – sometimes switching between them during a session.

Everyone’s lactic levels will be different and therefore their heart rate zones too – and as you get fitter your levels will shift. There are equations online to help guesstimate HR levels. “These can help,” says Marcus, “but they will not show you the point where lactate acid increases in the blood and when the energy systems change from aerobic to anaerobic.” To use HRM training accurately, you need to have a lactate threshold test at a running shop or centre.

There’s a neat and simple way to see that training with a HRM is improving your fitness. “When you first start using a monitor, trying to keep your HR low and stable feels like you are running really slowly. However, over a period of four to eight weeks if you keep your HR low, it will become stable on your runs. You will see that you pace quickens at the same heart rate – you will be running faster at a low HR.” If you started out only being able to run nine-minute miles in your HR zone 2 (generally below about 150bpm), if done correctly, after a few weeks you may well be running eight-minute miles at the same effort level.

Rest Is Best

A HRM is also an excellent way to detect the likelihood of overtraining and potential subsequent injury. “Your heart is a muscle and it’s constantly working,” says Marcus. “When we run it works harder and beats faster, but when we sit down our HR should drop to a resting HR, which should be a lot lower. Our resting HR shows us how recovered we are from training.” Look at your resting HR when you wake up in the morning over a period of days, to learn your average resting HR. “You will notice that the day after a long run, tempo run or speed session, it will have increased by about five beats. So an active rest day is needed to recover. “Resting HR can also show us when are coming down with a cold or another illness. If so, resting HR can be 10 beats higher, meaning a duvet day! So our resting HR is a really clear gauge of how we are coping with training and whether we are overtraining, fatigued or ill.”

Using a HRM has revolutionised Marcus’ running. “I also took 20 minutes off my 100km PB in 2015, running 6:56.13 at the World 100km Championships in Winschoten,” he says. “And I have been able to increase my training load and not get injured.”



Marcus Scotney has represented Great Britain in the 100K World Championships and has a marathon PB of 2:32. He’s also a sports therapist and part of the experienced coaching team at Sheffield’s Accelerate Performance Centre.  You can connect with Marcus at his website or on Twitter.


First published in Running Magazine, April 2016