I'm not sure if they thought this one through.....
(The Overtraining syndrome. Mark Jenkins, MD, Rice University)
There have been several clinical studies done on athletes with the overtraining syndrome. Exercise physiologic, psychological, and biochemical laboratory testing have been done. Findings in these studies have shown decreased performance in exercise testing, decreased mood state, and, in some, increased cortisol levels -- the body's "stress" hormone. A decrease in testosterone, altered immune status, and an increase in muscular break down products have also been identified.
I've read pretty much the same thing in every study I've seen (admittedly, not many, or enough to be considered comprehensive. I've currently got requests out to get more), none of which mention hCG at all, much less elevated levels.
Good luck to Mr. McNair, but I can't see how this argument will be sufficient to reduce or overturn the suspension.
Update: There is a chance that Cushing's story could hold water, despite my continued belief that the league is going to do nothing about it.
In this well-sourced article (.PDF) by Dr. Dan Gwartney it's suggested that hCG stimulates production of testosterone. If, as suggested by Dr. Mark Jenkins of Rice University, overtraining syndrome causes a testosterone deficiency then it's plausible that elevated hCG could exist as a countermeasure to lowered hormone levels.
Possible but, not yet proven as near as I can tell. I've got requests out to better researchers (with better research skills and tools than I have) for any information they can find on this issue, if something comes my way I'll be sure to share.
It's important to note that, even if the scenario I outlined above was plausible, or if that's even the defense that Cushing is going to use after all, he hasn't made it totally public yet, that minus peer-reviewed studies backing up those claims there's probably very little the NFL is going to do.
Except...maybe, fight this thing out in court.