Ive used B-12 before rugby matches for 17 years and had injections for a few of those years. It didnt pep me up, but when I had to dig down to find extra reserves they were there. Now that I only play socially I drink a 5 hour energy before a match, I notice the caffiene kick in and it helps the rest of the time. Ive used ephedrine and other substances to give me a boost or an edge, 5hr doesnt make you crash like alot of the rest of them.
It is far cheaper to just take the micro-dots(sublingual tabs) from WalMart. There is no crash because B-12 is a vitamin and most folks do not get enough in their diet.
I tried the 5-Hour a couple of times when I was working night shift and it worked as advertised. Finally I read the label and remembered seeing the microdots in WM. I went and bought a bottle of 236 for $2.00. Further study convinced me that the liquid form is he most effective and e 2 of the 500 size tabs would be equivalent to one 5hr. Actually I did great with just one tab and, being naturally cheap, did not go up to the 1000 units indicated. Somebody told my daughter to take B-12 for her sciatica, She takes the 2500s and has not been bothered by it in years.