I chose to try these when the brand that I normally take were out of stock. I tried taking 4.5 grams for preworkout about 45 min before I began my workout. By the time I had started my 2nd set in I felt so exhausted, as if I hadn't taken any pills at all. My muscles felt so spent already. I know I gave my body enough time to absorb the stuff but sorry to say I had a rough workout. I took 4 grams after my workout but I didn't even know if it was worth it. I bought the 30 serving size bottle, but I have to say that I didn't bother finishing it off. All I can say is that I can't recommend this product, since for the few workouts that I took this my body felt no different than if I skipped taking them at all. I had to go back to the previous brand I bought to avoid my muscles from feeling exhausted early into the workouts.