Tuning pacemaker for exercise

I'm 68, Ironman triathlete and ultramarathon cyclist. Resting HR 32 and I typically train 14-16 hours per week. I've been an endurance athlete for 50 years.

Last week I got a Medtronic pacemaker due not to bradycardia but to heart block and asychrony between the atria and venticles. Now I'm back exercising, although I'm not lifting weights (for the next 5 weeks), I am cycling and running. My pacemaker rate floor is set to 40 bpm and the ceiling is set to 150.

The symptom I see is that my pacemaker will, somewhat randomly, peg itself at the max HR setting during moderate to high intensity training. Yesterday, I was out for a relatively easy 6 mile run at a very consistent pace on a very flat and even surface and my HR would be 124 or so and in the next instant jump to 150 and remain there for 2-3 minutes before dropping back to 124.  This happened several times during the run. On the bike, I'm seeing similar effects with moderate tempo work, but especially during HITT intervals.

Does anyone have similar experiences and a solution?




by Tracey_E - 2023-09-12 12:50:41

When it jumped up, were you relying on the hrm for data or counting manually? Monitors aren't always particularly accurate for us so always count manually if something weird is going on. 

Ask if rate response is turned on. It will give a boost to the atria when we exert. If you have av block only, in theory the atria beats normally and rate response isn't needed. Sometimes they turn it on anyway and it can compete with our natural sinus rhythm. If this is what's happening, they an simply turn it off.

It's normal to take a few tries to get the settings fine tuned for athletes. Don't hesitate to go back if you don't feel right. If they aren't able to get it, sometimes a stress test is helpful to do it. They can watch what your heart and the pacer are doing in real time and adjust accordingly.

All doctors are different, but did they say it's ok to work up a sweat this soon? It has nothing to do with how good you feel, your heart, or your pacer. It's about infection risk. I was told to not do anything strenuous or swim for 4 weeks until the incision was fully healed. (if your doctor said it's ok, then go for it and ignore me!)

Your rate

by Good Dog - 2023-09-12 13:00:00

It sounds as though you have rate rate response feature turned-on, but you did not indicate that? Assuming that you do and in light of the fact that you just received your PM, it is most likely that you need adjustments to the rate response. That can take some time and often multiple adjustments need to be made to optimize the settings for your activity type and level. If it is turned-on and the Max rate is 150 bpm, then that could explain what happened at least to some extent. Have you discussed your return to this activity so quickly after the surgery with your Doc? It seems a bit soon, but that is a decision you and your Doc should make. 

If your rate response is not turned on, then it could be that your heart is just not responding on its own. Without the rate response turned-on the PM will not increase your rate with excercise. The PM only functions to keep it in sync and above the low limit setting. So it is difficult for me to guess what may be going-on. You really should contact your doc and discuss these concerns with him.



Exercise and pacemakers.

by Selwyn - 2023-09-12 14:09:40

It is difficult to know what is going on.  As Tracy_E says electronic monitoring can be inaccurate.

Rate response has differing rates of onset and offset. Your pacemaker EP can discuss with you what suits. 

The other thing to look at is the timing cycle- blanking time  - that is the period when the ventricles may not respond to an atrial impulse. Heart block itself may be intermittent. The balance between atrial activity and ventricular activity is important, especially for sport. 

I have just had my blanking time tweaked to stop excessive ventricular pacing. My heart rate would drop 20 bpm as ventricular pacing switched itself off after a period of time  Ultimately, settings are individualised to the persons pacemaker type, their activity, and their own intrinsic rhythm, if any.  I feel much better exercising as I now get some decent atrial filling. 

As long as you don't strain the upper body, like yourself, I was back to cycling within a few days of my pacemaker insertion as it is a shame to loose physical fitness. Of course, I couldn't swim until the wound was completely healed.  Cycling can give the pacemaker people a problem as the upper body may not trigger the rate response. I am told for the Boston Scientific ( which I had fitted for exercise) that the respiratory rate response for heart rate is best left off - UNLESS you are a competitive cyclist. 

You will find lots of advice about exercise settings under the search facility in the upper right corner.

Welcome to the club. Do let us know how you get on as well all learn from each other.

With best wishes. 

Exercise and Pacemakers

by sensitivebigguy - 2023-09-12 15:17:39

Tracy_E - The HR is being monitored with a chest strap and a Garmin Fenix 7 watch. As for returning to working out, I am doing less (only 11 hours this week) and with the advice of my cardiologist who said I could go for a run the day after surgery (in actual fact, I took the next day off from working out :-)).

Good Dog - Heart rate does increase with activity and mostly in ways that seem physiological. It's just these spikes for no discernable reason that seem abnormal.

Selwyn - that's a good thought. I'm not sure what the pacemaker uses as an indicator of need for increased cardiac output (other than increase SA node activity). I know some early pacemakers from Medtronic used a piezo electric crystal to identify physical movement, but I can imagine increased respiration rate being used too. I'll have to ask the doctor when I go see them next week. I have suggested we check it out on a treadmill but they didn't seem enthusiastic about the suggestion.

As for cycling, I've done all my riding indoors since surgery but I was thinking of going outside this weekend. For the indoors workouts: Zone 2 (easy) workouts result in slightly elevated heart rate (100-120) as expected. When I did VO2 Max intervals (1-3 minutes very hard, followed by 1-3 minutes of recovery), then HR would do a smooth increase to upper 120s to 130s and then spike to the max rate and remain there for a few minutes.

Thanks for your support and suggestions everyone!

heart rate

by georgeazarmitchell - 2023-09-13 18:21:23

When I exercise at times I will feel somewhat dizzy it lasts about 11 seconds . When that happens I sit down and I can feel the ICD 3-wire system pacing me out of a fast heart rate . My new device paces me when I need it . In the past I have been shocked many times so I know what that feels like by the earlier ICDS I have had but the new one tries to pace you out of  a high heart rate,It does this two times before administering a shock . I have not experienced a shock from my new ICD 3-wire system,but I have been paced out of any problems several times. Before this device, I would have to get Cardioversion every two months or so, not anymore. I got so sick of going to the hospital that I asked my Electrophysiologist to just do the shocking in her office . She said are you sure I said just tell me when it's going to shock me .She said when you hear a beep the shock is coming.By the time you feel it it's over, no big deal. Don't be afraid of getting a shock, it's not that bad and it is saving your life! Geo

You know you're wired when...

You make store alarms beep.

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As for my pacemaker (almost 7 years old) I like to think of it in the terms of the old Timex commercial - takes a licking and keeps on ticking.