What would my max heart rate be during exercise while on Inderal. I'm 52 and overweight and my resting HR is 89 without Inderal?

MAximal HR. In the absence of your beta blocker (Inderal), your max HR would be around 170, and your exercise target would then be around 120 or 130. Beta blockers blunt the HR-increasing effect of exercise, so you may notice it’s harder to get up that 120-130 range. As another gauge, your cardio should be intense enough that you feel winded but are still able to carry on a conversation with sentences.