I am very active physically. I work with horses and mules, and need my strength. I turned 70 this spring, and was noticing a slight muscle weakness I never experienced before. About the same time, I received a mailer on Advanced Amino, and felt led to try it. I have been on it for less than a month, but the muscle weakness was gone very soon after I started taking it. I will continue on this product! Thank you for it.