In “The Valsalva & Stroke” (10 Sept 2013, Starting Strength), Jonathon Sullivan, MD, PhD, SSC, writes:
Athletes who engage in serious, programmatic, heavy resistance training will do so under Valsalva – whether they want to or not, as we shall see. And a very small number of them do, in fact, suffer hemorrhagic strokes. But is this a cause-effect relationship? Is there either a physiologic or evidentiary basis for claiming that the Valsalva is unsafe under a load? Are you going to die?
Good article with good food for thought.
The Valsalva maneuver is something we do naturally when we push a car, strain under a load, even (sorry to the queasy) sometimes when we go to the bathroom. And, Dr. Sullivan points out:
In the three centuries since Valsalva’s death, the physiologic consequences of holding breath against a closed glottis have led to the use of the maneuver in basic research and clinical medicine. In my own practice, I have asked patients to “take a deep breath and bear down” on hundreds if not thousands of occasions – during deliveries (where it has been pro forma for centuries), during vascular procedures (to fill the jugular or subclavian with blood and make it easier and safer to insert or remove a central venous catheter), or in the setting of supraventricular tachycardia, to restore sinus rhythm (where it occasionally works, but not nearly as often as we would like). To date, no patient has ever stroked in front of me during a medical Valsalva. But I’m getting ahead of myself.
So, for most people, all good. Pretty much the only issue to worry about is when you have a pre-existing condition (in which case, you shouldn’t be lifting heavy, anyway):
Looking at the literature on ICH and lifting, we find that most ICHs were of the SAH variety, and those that underwent anatomical investigation were almost always associated with ruptured berry CAs. The epidemiology of this rare phenomenon is still sketchy, but it is fair to say the literature gives us no indication that resistance training increases the risk of ICH in the absence of severe uncontrolled hypertension, coagulopathy, congenital aneurysm or other underlying cerebrovascular pathology. In other words, if you don’t already have a time bomb in your head, it probably won’t go off, no matter how much you lift and grunt.
This means that any consideration of an increased risk of hemorrhagic stroke while lifting under Valsalva is practically restricted to those who have such lesions. This is both a reassurance (because the incidence of such lesions in the population is so low) and a concern (because people who have such a monster in their head generally don’t know it, and there’s no quick-cheap-and-easy way to screen for them).
So go for it — as long as you are smart and healthy. If you go hard without being smart, you might go home in a coffin. So please be smart.
If you want some practical tips about it, read e.g., “Valsalva Maneuver: A Weight Training Breathing Technique” (1 December 2012, King of the Gym) by Alex.