Well, getting off the beta blocker certainly complicated my exercise. I was under orders to go just by feel until I could do another stress test on the treadmill, so I did. It takes some time for your body to adjust to being off the drug, and apparently there is some overcompensation in your heart rate that should dissipate in a couple of weeks. Anyway, my RPE was about the same off the beta blocker as on it, for similar power output on the bike or running speed. But predictably my heart rate settled much higher than it had before: on the bike at about 155-160, and running at about 165. These in comparison to my prior limit of 140.
I had some bloodwork done for my treadmill test appointment, and the rehab called me to say that my creatine kinase was pretty high, so they might need to tweak my cholesterol medication. I said I wasn't on any, and they looked at my file, then asked me surprisedly how hard and how much I've been exercising. Turns out I'd been overtraining! Creatine kinase rises in your blood when your muscle breakdown from exercise (or other reasons) is higher than is really sustainable. So I backed off, tapering for my all-important treadmill test.
Well I was ready to nail it at this test. I felt strong and fresh, and I was crestfallen when I was stopped after 9 minutes, at a fast uphill walk and before I felt like I was working at all. Turns out my blood pressure limit of 160 (due to the fact that I have an aorta graft) was going to be my limit. New HR limit is 145. Ugh. That limit should come off at my next cardiologist appointment hopefully, which should be in December.
So, I've been jogging very slowly and riding my bike very gently on the trainer. It feels like a big step backwards, but it isn't really. The beta blocker was masking this, and now I can see the real state of affairs. My resting heart rate has been quite high (mid-80s), though I think that's starting to creep down. I've also found that when I'm riding my bike my heart rate gets way over 145 very easily... that is unless I grind at a pretty low cadence, around 70rpm. This is very odd for me, as I've historically preferred to ride at around 100rpm, and my bike riding since surgery has been around 90rpm. But I guess there's something about that high cadence that my heart really needs to work for, so I'll do something new for now and grind.
My bike numbers were not showing any progress until I found this low cadence solution, and since then I've been able to track a steady improvement. When my low-cadence power at 145bpm is higher still, I'll try lower power at a high cadence and see what my heart does.
Patience, patience, patience...