As stated in the title, do we have any evidence that having a big muscular arm influence BP measurement?
There is evidence that a muscular arm will produce a higher systolic reading if the wrong sized cuff is applied.
There are two measurements in a blood pressure reading, the systolic and the diastolic. The systolic blood pressure (SBP) is the first number in a reading (Such as the 120 in 120/60), and the diastolic blood pressure (DBP) is the second number.
The method for taking an arm blood pressure is to wrap the cuff around the upper arm, place the stethoscope over the brachial artery, and inflate the cuff until you cannot hear any sounds. Slowly bleed the air out of the cuff, and note the number when the first sound appears, and when the sound disappears to get your reading.
The study I refer to above was performed at a Mexican bodybuilding competition. When a medium cuff was used, the SBP was significantly higher than with the larger cuff. Blood pressure overall was slightly lower with the correct sized cuff as well.
So while being muscular is not really a factor, clinicians should be aware of using the correct sized cuff to avoid artificially inflated blood pressure readings.