Originally Posted by
Maybach
The blue book discusses lightheadedness on the press, and as you say, is generally thought to be due to increased pressure on the carotid sinus, which can provoke a baroreflex action at the heart which causes a rapid drop in blood pressure (similar to a "sleeper hold"). The solution given is to take a new breath between each rep (and therefore reduce the exposure of the sinus to high pressure). I have had...mixed success with this technique. The times I get lightheaded on the press seem to be due to the actual muscle contraction in the area (since it appears to be randomly and uniformly distributed among "heavy" reps, such as first reps or singles, rather than merely later or especially effortful reps). This would seem to jibe with your experience of it on the pin press more than the full press. And the loss of "tightness" required to take a breath can in some cases costs at least a full rep. It is perhaps a matter of insufficient skill on my part on taking a shallow enough breath to alleviate pressure but not to lose tightness, but that's as may be.
It is possible, I suppose, that a "heady" Valsalva could increase pressure on the carotid sinus sufficient to provoke this action, and if so, a mouth guard could alleviate this. Then again, a well executed "heady" Valsalva at the right time can also work to alleviate this faintness if it's not too severe.