htrf wrote:
The loss of coordination and collapsing with reasonably quick and total recovery suggests to me a vascular issue, probably related to transient low blood pressure. Of course if this is the case it could be down to any number of reasons. But failure of blood pressure regulation is the obvious culprit from the information given.
Not a bad guess, but please call it what it is (a guess). Which vascular issue? likely not ischemic claudication from sclerotic arteries in a healthy young non-smoker. Are you thinking about a vasculitis? also extremely unlikely in this scenario. Transient low blood pressure?? More likely, sounds like you're thinking vasovagal syncope however it is interesting this only occurs during races...
My leading guess at this point would be a mental thing. I do not know the athlete and cannot say, but you would be tuned into this as a coach so I'll defer to you for that evaluation. Also, is he taking any meds? trying anything different before his races (eg red bull, caffiene pills, etc?).
If it is not this, I would start hunting down the zebras. Namely, WILSON'S DISEASE should be ruled out. I'm not sure how extensive his workup has been, but I would get orthostatic vital signs (to see about a neurocardiogenic problem), a basic chemistry, CBC, Ceruloplasmin (for wilsons), EKG, and even consider an echocardiogram to make sure he doesn't have a heart defect (hypertrophic cardiomyopathy can present this way, but would typically be symptomatic in practice too). All but the echo could be done in a 20 min outpatient office visit (wait times not included) and pending the results I would also consider evaluation by a neurologist.
G'luck coach.