It’s obvious to highlight that heart rate (beats per minute) increases significantly during exercise, let alone when you’re running a marathon.
And while few runners actually target or think about a specific heart rate threshold during a run, there are so many variables that can affect it – such as pace, body temperature, energy levels (carbs and glycogen stores) and the weather on the day.
Last Friday, it’s fair to say most of us experienced the cardiovascular drift – a natural, progressive increase in heart rate when running. But, even if you were running at a constant pace, there can still be change with ups and downs in your heart rate as the following statistics show.
My average resting heart rate, according to my Garmin Forerunner 35, is around 44 bpm and during my Dubai Marathon run (overall finishing time 3:33:39) – my heart rate hit a peak of 186 around the half-marathon mark and my average was 167.
My average pace per km between the startline and 30km was between 4.20 and 4.60, before injuries took their toll and my speed decreased during the last phase of the race.
But for the bulk of the marathon, as the graphs below help to illustrate, my aerobic threshold zone (80-85% of your maximum heart rate) was close to my overall average.
Basically, the quicker you run – the faster this tends to be. For elite athletes – they will be hitting the summit of their maximum zone for a lengthy part of the distance.
GRAPH 1 – MY AVERAGE AND MAXIMUM HEART RATE
GRAPH 2 – THE WHITE LINE SHOWS MY AVERAGE
My heart rate plummeted towards the backend of the race.
WHAT DOES IT ALL MEAN?
Basically, the more time you are immersed in your aerobic threshold – the more you are getting out of yourself, using your energy in the right way, maximising your effort and managing fatigue levels.
Having an idea of your training threshold and keeping track of it is a good thing, but getting bogged down by statistics isn’t the way forward.
Continue to focus on your nutrition, training, routine and running goals – and your training threshold should look after itself.