Pacemaker tuning for mountain biking

I am a 71 year old mountain bike enthusiast but I can't keep up with my friends anymore. I had my pacemaker put in about 5 months ago. After the initial disorientation I started taking data on heart rate during my rides (apple watch). I felt that my heart rate was too low (130 bpm) during steep pitches. Gradually we've increased that over the months to 150 bpm with the slowest recovery time possible and supposedly a pretty sensitive to motion response.  I am learning how to "fool" the pacemaker with unnecessary upper body movements to get the rate up. But, in my data collection effort I am seeing that the higher I keep my heart rate the slower my times on a known circuit. Do I have the reslationship between heart rate and muscle power output confused? Should I dial back on worrying about heart rate and just relax? I would like to get back to keeping up with my friends. Thanks for advice.

2 Comments

Numerous factors to consider

by crustyg - 2020-09-11 17:41:18

Your health profiile is pretty thin - why do you have a PM? - so I'm guessing a little here.

HR is only a proxy for cardiac output - which is what you really care about.  So, no, you don't have things wrong.  Up to a point, increasing HR increases blood supply to the big muscles you're using when climbing.  But other factors matter too: filling volume, A=>V synchrony, Hb levels, blood oxygenation (%sat), and %LVEF.  You probably know that athletes *tend* to increase cardiac output more by increasing stroke volume than stroke rate - at least at first.  And return to nearly normal HR is a good measure of fitness.  You can find several comments from AgentX86 and myself about the importance of A=>V synchrony - it makes a *lot* of difference to athletic performance.

Ideally, your leg muscles will be reaching their maximum capability at around the same level where HR/cardiac output is also max.  No point having a huge heart belting out blood with tiny or unfit leg muscles, and obviously a low HR will make it difficult to climb.

Sounds as though your EP team are being sensible: your maxHR might still be a *little* low, but a lot depends on the health of your heart muscle and capabilities of your coronary arteries.  Heart muscle only gets oxygenated blood when relaxed, while higher HRs increase cardiac muscle oxygen need at exactly the time that oxygen delivery is being reduced due to the high rate of contraction.  Even teens/twenty-somethings go into HF with sustained atrial tachy of 200+ (e.g. untreated WPW) - and quite quickly.  A couple of hours can do it.

Lots of things for you to consider: normal haemoglobin levels, healthy heart/coronaries, A/V sync, good pre-filling (salt and water in your diet and no diuretics), drugs (e.g. beta-blockers).

HTH.

I would say if you feel good

by PacedNRunning - 2020-09-13 22:16:27

I would say if you feel good, I wouldn't worry about heart rate.  If your heart is not giving you what you need, you will feel it.  

You know you're wired when...

You participate in the Pacer Olympics.

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I have an ICD which is both a pacer/defib. I have no problems with mine and it has saved my life.