Cycling heart rate

I am 72 years old and been cycling for 17 months, did 2200 miles last year and 400 this year. It is April in Penna.  I am struggling on hills and this manifests as not getting enough oxygen; really short of breath on hills. My heart rate does not increase at a rate that correlates to my exertion.  Throughout the winter I did SPIN classes 3X week, HITT on a stepper machine and rowing machine (same results) and EWOT on the stepper machine (the 90% oxygen worked well).  I do at least two 3 hour rides a week to build a good base. BUT the hills reveal the disconnect of effort and heart rate manifested by seamingly lack of oxygen. I have a St. Jude PM2240 device placed in summer 2017.

If you have had a similar issue, please advise what worked for you. 



by Tracey_E - 2020-04-09 15:53:41

If you are depending on the pacer to get your rate up on exertion, the St Judes models are activated by movement. So if you go for a run or lift weights, it senses movement and raises your rate. That's why you might sometimes notice your rate going up if you drive on a bumpy road. Bikes, not so much because your torso isn't moving. Rowing and stairsteppers are hit or miss, depends how you are using your arms. There are some sensitivity settings they can tinker with, that should help with rowing and step. I've never heard of a good solution for the bike, sorry.

When it's time for replacement, talk to your doctor because there are some other brands that go by breathing and don't depend on movement so they are better for sports like cycling. 

Get a better PM!

by crustyg - 2020-04-10 05:19:33

Sorry to hear that you've got this problem: not enough was discussed about your preferred activities before your EP doc chose and implanted your PM.

Road cycling (and rowing machines) produce little upper body movement and as Tracey_E says, that means that the accelerometer in your PM doesn't detect much movement so it doesn't drive the rate response feature to increase your HR.

There are only two PM vendors worldwide who have a breathing measurement feature that also feeds into rate response: BostonScientific is probably the better known (got the technology from their acquisition of Guidant - based in Belgium, the other based in Italy).

Sadly I don't think there's much you can do to fix this: certainly get your EP doc to turn the accelerometer sensitivity up to maximum, perhaps increase the delay before it takes effect (so you don't overdrive your heart from walking to the kitchen or upstairs).  Mountain biking is likely to be better - much more vibration which your PM can detect - both up and down hill.

I'm a keen road cyclist, done 1600k and 22,000m of climbing so far this year and my Accolade was deliberately tuned for road cycling on a static bike.  My PM isn't much good during Yoga and Pilates, but that's life.

One thing: what's your permitted maxHR? Many EP docs are very nervous about giving athletes a high enough maxHR.  I had to really charm my doc to give me more than 130bpm (and I'm younger than you) but I've had it tweaked and have a sensible compromise at 165bpm.  I wouldn't be surprised to hear that you are stuck at 130bpm?

Accelerometer , breathing, . pacemakers for exercise.

by Selwyn - 2020-04-10 06:04:01

As mentioned above, the problem lies with the accelometer in your pacemaker. This is used to change the rate response  to exercise of your PM.

The accelometer is sensitive to movement ( like a little ball bearing at the centre of a tilting clock face, as used in smart phones to turn the image from portrait to landscape.). If your upper body does not move a lot, you are not going to get a heart rate increase of any significance, given your type of PM. You can have adjusted speed of onset ( for heart rate) and offset, and upper rate and lower rate. 

Newer pacemakers are in development to try to overcome these problems. I believe the PMs that try to increase heart rate by measuring transthoracic impedence ( ie. breathing,  such as those made by Boston Scientific ) are fraught with problems according to my PM department - the techs. tell me they often have to turn off these features  as folk are experiencing  difficulties.  

Always interested to hear other people's experience of the Boston Scientific range of PMs using their RightRate® technology.

( see

and similar).


Cycling heart rate

by DOG - 2020-04-10 10:23:11

It is great to read this information about my PM  (St Jude PM2242).  I thought I was not training hard enough or needed to lose more weight. Weight 174 at 5' 9.5" -- high school weight. Could anyone tell me more about this acceleomter, that must be in my device?  I do not know where max herat rate is set.    I know on some difficult hills, when I am getting light headed my HR will be 145 to 149.  This would be at my calculated max.   Where should my HR max be set?

Your EP tech/team set this for you

by crustyg - 2020-04-10 12:19:51

The maxHR that your PM will provide/allow is set in the PM itself - you can't get at it.  One of the frustrations of a PM is that it's like being in the 1950s - your doc tells you what you will have and that's it.  Medication you can choose to take or not (but there are significant risks in this), but with your PM you have to accept what you've been given.

Ok, so you're into the charm and negotiation.  You convince your EP doc (and sometimes EP tech) that you understand what's going on and why you need a higher maxHR and that it's a sensible value given your heart health (esp. coronary artery health) and they graciously allow you the requested value.  Actually 150bpm isn't that low, but perhaps you're having to work too hard to get there.

The accelerometer is a tiny chip in your PM exactly like the one in a smartphone that tells it which way is up (detects gravity), and as the PM moves around the accelerometer produces signals which are fed into a software routine that is written to push your heart rate up - the assumption being that more movement means you need greater output from your heart and for most of us that means more heartbeats per minute =>increased HR.  The software will wait a while after movement increases to avoid overpacing your heart, and will provide a certain amount of HR increase for any given level of exercise (the sensitivity).  These factors are also able to be set by your EP tech.

You should be able to find a reference manual for your PM on the manufacturer's website - well worth downloading and reading.  Any questions post them here, and next time you see your EP team you will know how to phrase your requests and requirements.  Once they hear you start to use the EP jargon they will usually listen to you a lot more carefully.

@Selwyn: interesting what you say - my first follow up by the big EP team the tech nonchalantly said 'Oh, you've got Minute Ventilation enabled - we normally turn that off.  My somewhat emotional response was in the 'Touch that and Die' category (see my post about how happy PM owners become unhappy).  All ended well.  Properly set up and correctly tuned the MV feature is brilliant, reliable (but not perfect) and enables me to enjoy road cycling).  Sad to say, many EP docs/techs don't really understand how to tune MV, IMHO.

Rd Cycling with a Boston PM

by Deano768 - 2020-04-18 10:22:54

Good Afternoon,

I've just joined the club so hello to all. I'm also struggling with a lock of oxygen and when exercising. I had my PM (Boston) fitting at 39. Now 40 and trying to get back into my fitness as close to what I was before I starting having problems (1st n 2nd Degree AV heart block.  I've been back twice for check-ups and all was fine, bar a few settings being changed in an attempt to make the PM react a little quicker.  I currently have it set to a Max 185 which i can reach at times when training hard. However more often than not when cycling or running when hitting the hills, I also run low on oxygen as it’s like a funny swoosh through my back and is an instant stopper. When looking at my heartrate on my watch (which I cross ref with the EP Tech's machine it was only one beat out in comparison so I do trust the watch) it could be reading anything from 90 - 120 and at times going down as appose to up near my max where it should be as I would be pushing hard. 

The question is has anyone else experienced this with a Boston PM, is playing up or do I need to have some settings changed. 

Thank you in advanced.


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