Ever since I started living like a gerbil I've taken my blood pressure before and after running on the treadmill. At first, my BP readings were all over the place, typical of what I've observed over the years.
I've mentioned the pulse rate chest strap I wear on the treadmill before. Because I put this on to manage my treadmill speed and ramp, it is always on when I take my BP. The BP device also displays the PR. A while back I started comparing the PR from my chest strap, known to be accurate from testing at cardiac rehab, with the PR from the BP device. About half the time the two readings were extremely close, but the rest of the time the BP device was reading much lower indicating it was missing beats. If it can't properly read a beat, it can't produce a good BP reading. When it is missing beats it *always* reports a higher BP. For example, yesterday it reported 152/82 on the bad test, 108/59 on the good test.
Holy shit, you say? The bad reading could be justification for taking BP meds. Since I've started discarding all readings where the PR variance was more than two beats my post-exercise readings have been extremely consistent. Here are the last seven systolic: 108,108,106,106,101,114,106 and the last seven diastolic: 63,59,58,63,63,65,60
It's really easy to check your own pulse rate by counting your wrist or neck pulse for 10 seconds and multiplying by six. Next time you check your BP compare the machines PR with what you get. If they differ, discard that reading, adjust the cuff slightly, and try again.