I can find copious health sites that cite (heh) the fact that squeezing a ball reduces blood pressure, but my Google-fu is failing me, and I can’t actually find the trials/experiments that demonstrated this.
Does anyone know the original article(s) that showed this to be the case?
Did some further digging, and it turns out that using the term “isometric exercise” rather than “squeezing a ball” increases one’s success in Googling this. Ignorance self-fought! 
BTW - It seems to me that squeezing the wrong ball might actually increase blood pressure - at least temporarily. 
Dran - I was going to say that it probably depend on who is doing the squeezing.
The first time I read the title, the idea of a non-biological ball didn’t even enter my mind.
LOL! Now, the kernel of truth to your little jape is that one review article I read said that there was concern that isometric exercise may in fact acutely raise the blood pressure of hypertensive patients to a potentially dangerous degree. But it would appear that those concerns have been alleviated, and that modest chronic decreases have been observed.
So on the dope, even smart-ass comments can lead to insights! 
I am a smart ass, and don’t you forget it! 