I think you should be looking for a study that
proves there is a correlation between increased risk for cardiovascular damage and piracetam/modafinil consumption, rather than looking for studies which
dismisses a correlation. Typically what sparks a study is first an observation "oh, Subject X took modafinil and then died running on the treadmill later today", and as far as I know there's no cases of that happening. Exercise is good for you, and taking nootropics/stimulants doesn't really change that. Besides, if anything bad was going to happen, on say amphetemines, when your blood pressure is above normal...your body would start saying "STOP RUNNING!" before you had a heart attack. The young body is also designed to cope with this drug-induced high blood pressure. It's the reason that kids using adderall don't keel over and die on MODERATE doses.
In fact, here's a study where they measure
exhaustion time during
intense exercise:
http://journals.lww....xercise.23.aspx.
If these guys are literally sprinting to the point of exhaustion on modafinil, surely no acute risks exist.
Still, I wouldn't recommend using modafinil to become superhuman and run faster than normal. So in short, if you're using modafinil "occasionally" TO STUDY, there's nothing that will do to your running abilities or cardiovascular health.
As for piracetam, that's like asking if table sugar will make running unsafe.
