Threshold and slope adjustment

• by bhdavis
• 2017-04-05 10:19:21
• Exercise & Sports
• 1980 views
• 3 comments

HI all,

I'm a 67 year old male that had a St. Judes 2-wire pacemeker installed last November in response to the development of Afib.  I needed the Packemaker because the 25mg of Metoprolol my cardiologist wanted me to start taking was going to slow my heart rate.  After 35 years of running I had a resting rate in the low to mid 40's and a sleeping rate in the low 30's.  The pacemaker is set on the low end at 60 bpm.

I began running again about six weeks after the pacemaker implant.  Now 5 months in my running distances are back up to my pre-pacemaker half marathon distance level but my strength, endurance and speed are way down.  The first half mile of my runs have required a significant effort and during the runs my heart rate for the most part has stayed in the 95 to 120 bpm range.  I felt the pacemaker was not kicking up the heart rate quickly enough towards its high limit setting of 130 bpm and as such I wasn't getting enough oxygen through my system.

I saw my cardiologist yesterday and after discussing all this he kept the high end at 130 bpm but adjusted the threshold and slope levels with the goal being to kick up the heart rate 10 to 20 bpm while running.

This morning I tested it out.  I did a 4 mile run and it was indeed easier then in the past months so I'm optimistic.  It's only the first day on the new settings though so time will tell if this adjustment is heading me in the right direction.

I'm posting all this because my Garmin heart rate monitor watch (confirmed by physical checks during the run) shows that after an initial high error reading at the start of the run (typical for Garmin watches) the heart rate leveled out to a 129 to 131 bpm rate.  It's as though the new slope that was set for the pacemaker might have set the rate to kick up all the way to 130 too quickly.  The heart rate did not vary by more than 2 or 3 bpm for 3 1/2 miles, not even when going up and down the hills on the route.  Plus this was a loosen up run after a long run this past weekend so I wasn't really pushing very hard.  While the run felt good I'm wondering if maybe the threshold and/or slope adjustments need to be brought back down a little.  It's very strange to have the heart rate the same whether I'm cruising down a hill or working hard to get up one.

Since this is just one day into the new settings, and I don't feel like there are any particularly negative impacts from the changes, I don't want to bother my doctor with this.  I'll give it at least a week or two and then call him if I think it's necessary.  It's just so strange to see the pacemaker level out at the 130 bpm high limit.  The Gramin graph looks like a flat line at 130 bpm over 3 1/2 miles whereas in the past the graph shows the heart rate going up or down depending upon the elevation changes on the route as one would expect.

Does anyone else out there have any experience in this area? 

Thanks,

BH Davis