F5 is possibly the strongest pre-workout we have designed to date. F5 was formulated with the strength athlete in mind. Beta testers reported a huge increase in focus and energy, mind blowing pumps and endless stamina in the gym. Below is a quick rundown of the ingredient profile. Amentoflavone is a new stimulant that increases calcium uptake in the muscle for more powerful contraction. We also have a strong dose of betaine anhydrous and huperzine a.