Does it affect your reflexes or concentration?
not really reflex and concentration......
it threw me off like I have no conditioning (up high then crashed and burned effect) couldn't really control the workout put and gauge my stamina properly...basically energy level was up too high when I didn't need it to be up that damn high and I felt burnt out alot faster....thus making me feel like my stamina and conditioning was shot..no longevity.
hydration levels were off big time also I felt. normally when I train boxing I'll go for 45 minutes with trainers little to no rest in between rds and can go without water and keep stamina,not feel too tired.etc and recover..etc..ephed wiped that out completely and I was out on my feet pushing way too hard..couldn't fight in spirts, couldn't do alot of things that I normally do and I was fu*king thirsty as hell. LOL
I only needed to try it once to learn.

I was a fool for even trying that sh*t.