Key substances in Acti-Flex 4000 work together to improve performance by increasing the horse's supply of joint-lubricating synovial fluid, which repairs and strengthens body parts that running puts under high stress. By supplementing what a horse produces for itself, Acti-Flex 4000 greatly speeds the body's self-repairing processes. MSM adds a powerful ability to improve sulfur bonds, which are an essential component of all connective tissue. Ascorbic Acid (Vitamin C) is a key to optimizing bioavailability of the other ingredients, as well as being an essential antioxidant. Boswellia Serrata is an herb that is proven to reduce inflammation. Type II Collagen is the major protein found in cartilage and is is the "glue" that holds cartilage together as well as providing elasticity within the joints. Hyaluronic Acid (HA) plays a critical role in maintaining healthy joint synovial fluid and preventing the deterioration of aging, over worked joints.