For those who train with heart rate monitors, you have probably encountered a session where your HR graph just doesn’t make sense. With my garmin it used to start fine then my HR would skyrocket up to the 180’s 190’s and I would be dead if I was there 200’s. With my Suunto – sometimes I would get no reading before it kicked into life …
After you finish your activity and get back to your computer, you’ll probably see something like this – a major HR spike a dropout or even a level no read situation, followed by more normal HR activity: Below is my reading from the Alloa Half Marathon on the weekend with flouro yellow highlights of bits that don’t make sense ….
Frustrated, you wonder if the battery needs changing but then the next time it is fine so you forget about it …but here is a reason why this might be happening.
I presume everyone can put their strap on correctly – that is the right way up and against the skin just under the ribcage …
So assuming that you’ve got it fitted right then let’s look at what typically causes the spike or dropout in HR
1) Are you wet yet?
During the winter months and in the case of Alloa on Sunday the air is often fairly cold, and fairly dry. This means that you’re less likely to have moist perspiration on your skin (from heat) and even less likely to be generating any sweat right from the start of the workout. This in turns lowers your belt’s conductivity ability to read your heart rate beats ….. Simply introducing any moisture at all will usually remedy the situation – at least until you begin sweating enough to let sweat do its job.
2) Synthetic quick dry shirts:
At Alloa I was wearing a synthetic shirt as opposed to my ‘normal’ nicer smelling Merino. An unfortunate side effect of synthetics is that they can dry out the body and the skin’s sweat making the belt so dry that it can’t ‘read’ the skin. Another issue is that synthetic material can build up static which can cause electrical interference with the HR belt.
3) Your mum is a gorilla:
I have heard some people of the hirsute variety have more errors ….. you need to be very hairy for this to affect the HR belt but if you are this way inclined … a) shave or groom b) stay swinging in the trees instead of running c) if female remain indoors and plait that hairy back …..
How to lick the problem:
It is pretty easy to fix
1) Sweat it: This first one is a bit obvious – but will explain why the problem often goes away after just a few minutes of activity. Once you start sweating it improves conductivity. This in turn makes the HR strap work …. but you still have the earlier misread ….
2) Lick it: This is the simplest option and what I do all the time. I just give the sensors a good gobbing – but hold onto your bogeys for the run.
3) Heart Rate Gel: If you suck at licking, then you can instead use electrode gel to improve conductivity. This is what’s typically used in medical environs for scans and using TENS machines …. it just ensures a good contact moisture seal between belt and skin. They are cheap as chips – about £5 for a big tube that will last years … If it is a dry very cold day and I remember then I use gel on the belt before heading out.
4) Shift the strap:
If you spot a dodgy reading then adjust the strap – a quick shift up and down normally gets the belt to rub against some sweat and the belt normal corrects pretty quickly. Some people shift the strap so it is half on back and front or even all on the back … i have not tried but it seems to work as an option.
5) Replace the batteries:
Finally, it could be as simple as old depleted batteries – most belts use CR2032 batteries so i always make sure I have a handful around ….