Sport Performance. Prevent Muscle Breakdown. Increase Muscle Strength. Makes Taking Fiber Easier. Prebiotic Soluble Fiber. Flavorless Powder. Muscle Fiber by Finaflex combines a blend of two muscle preserving and strengthening ingredients with a Prebiotic Soluble Fiber. Muscle Fiber features two categories of ingredients that are often taken separately into one complete and novel dietary supplement.Muscle Fiber with robust essential Amino Acid L-Glutamine, Vitamin D3, and Fructooligosaccharide (FOS), three ingredients that are crucial to muscle preservation, digestive health, and overall well being.