Phosphatidylserine (PS) is a naturally occuring compound found in many foods such as vegetables, soybeans, rice amd fish. It is necessary for proper functionming for all mammalian cells and in humans it's found in very metabolic tissues such as skeletal muscle, the brain, the heart and the liver. It is involved in how cells communicate with each other and in the regulation and release of important hormones such as noradrenaline, dopamine and acetylcholine.

In the 1990's research showed that PS enhanced brain and cognitive functioning. At the same time, studies showed PS affected the secretion of the hormone cortisol after exercise. Highly elevated levels of cortisol post-workout are associated with immune supression and tissue breakdown-not a good scenerio for an athlete.

A couple of years later researchers performed some dose related studies. A group of men were given eithr a placebo, 400 mg PS or 800 mg PS for 10 days. They then did a vigorous exercise session. In this case it was found that the 800 mg of PS slowed the release of cortisol without affecting growth hormone secretion. The 400 mg group experienced no effect on cortisol levels whatsoever.

More research advancements came about six years later. It was discovered that not only did PS slow the release of cortisol after exercise but it also decreased levels of perceived exertion and post-exercise muscle soreness.

Well into the 21st century researchers began to look at PS's effect on endurance. One study had participants complete three 10 minute cycling bouts at work rates designed to elicit 45,55,and 65% of each cyclists VO2max. They then performed one more round at 85% to exhaustion. One group was given PS, the other a placebo.

The results showed that in may ways there were no differences between the two groups. However, those who had taken the PS between the first two cycling bouts increased their time to exhaustion from an average of 7 minutes 51 seconds to 9 minutes 51 seconds- an increase of 29%!The placebo group showed no improvement at all.

There are a couple of theories as to why PS could aid endurance performance. First, PS may accumulate in the heart cell membranes enhancing contraction, thus improving performance. A second theory postulates that PS can act as an antioxidant, reducing post-exercise soreness and blunting cortisol levels. Finally, some researchers feel that extra PS accumulates in the cell volume (not in the membrane) and helps activate enzymes that move sodium, potassium and calcium ions in and out of muscle cells. This would help reduce early fatigue.

Many studies have concluded that PS is safe. It's only side effects are positive-mental clarity and lowered stress hormones. While more evidence is need to determine it's mechanism and it's effectiveness for enhancing endurance performance there's nothing to lose by experimenting with PS. Whether or not you choose to take PS for a test spin, remember there's still a lot to learn about this compound. Athletes and their coaches should keep their eyes open for any and all new research on PS.
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Dr. Lanny Schaffer is an Exercise Physiologist and the President of The Intenational Fitness Academy. For more training tips and supplement information go to http://www.aerobics-exercise-coach.com