Frustrating early heart rate highs MAF training

by Stuart
(Stratford upon Avon )

Hi Nicole,
I am really confused and frustrated (early days) after this morning’s MAF run. We ran 10k and spent the whole time stopping to walk every 20/30 metres. Average pace was over 9 minutes per km! However, yesterday morning I ran with my daughter on only her second attempt at 10k. I decided to just run with her for her and not watch my heart rate. We ran very steady at a sub 7 minutes per km pace. When I looked at my heart rate afterwards it was fascinating. For the first 2k it was up in the 140’s, well above my 126 “MAF” pace. But then it appears to have settled into a very consistent rate in the low 120’s, perfectly within my MAF expectations for the remaining 8 km. I simply can’t understand this. I welcome your thoughts.

Many thanks

Nicole's Reply:
Hi Stuart, thanks for your question. Erratic heart rate readings are a common problem. It is difficult to say why your HR jumped about but it could be one of a couple of reasons.

Sometimes we just have off days. Maybe you didn't sleep well or were feeling stressed, perhaps you were coming down with something or maybe you were looking at your watch too often so it was making you anxious or maybe you drank an extra coffee or had coffee too close to starting your run. There is also the weather, the terrain, time of day and so on.

The second reason, is your heart rate monitor. I don't know if you are using a chest strap or your watch but the watch HR monitors are often known to be unreliable. I use a Garmin Fenix 5S and I find that the first few minutes it often picks up my cadence rather than my HR. I also need to make sure that the contact point with my wrist is tight and I find that after I start to sweat a bit the contact improves. Chest HR monitors seem to be more consistent and reliable but then some people find them uncomfortable.

As you progress with your MAF training, you will begin to work out what makes your HR spike or be extra high. Either way, try not to stress about it too much as that in itself makes your HR jump. I hope that helps :).

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