A mate and I have been meeting at the local pool each week to practice some static apnea, and my breath-hold time has steadily improved. Occasionally though, I have a week where I can’t even match the time I started with a couple of months ago.
I realize there are many factors at play here, like how much recent exercise I’ve had, and how much sleep, alcohol, caffeine, etc., but I’ve noticed that on the two occasions I’ve had really poor breath-hold. times it’s been after a delicious dinner of spaghetti and garlic bread the night before.
I seem to remember a sign in the local hospital asking people coming in for surgery not to eat garlic the night before, and I’ve often wondered what effect garlic has on my cardiovascular system. Is it a potent substance I should avoid before, say, deep decompression diving?
Along with its ability to deter vampires, a large number of health benefits have been claimed for garlic over the years, from lowering cholesterol to fighting cancer. Very few appear to have a legitimate basis; the majority remain inadequately studied or appear ineffective.
Here’s how the National Institutes of Health Division of Complementary and Alternative Medicine views garlic: http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-garlic.html
As regards to your questions, garlic has mild anti-clotting activity. Therefore, excessive bleeding may be a concern, so patients preparing for surgery may be asked to refrain from eating it starting a day to a week (depending upon the source) prior to the scheduled procedure. This is of particular concern for those who also are taking other products that may predispose to bleeding.
Taken in anything resembling normal concentrations, garlic is not a “potent substance” (other than for the effects eating it has on the breath) and there is no apparent reason for the diver with a normal blood-clotting profile to avoid it before diving, deep decompression or otherwise.
Regarding your observation that you’ve had poor breath-hold times after a spaghetti-and-garlic-bread the night before, while it’s possible your breath-hold times may somehow have been adversely impacted by the amounts and nutritional composition of what you ate the prior evening, as well as by how much wine or other alcohol accompanied the meal, and how late you partied, I can pretty much assure you that garlic in and of itself didn’t contribute.