Manganese strengthens tendons, tissues, and ligaments. It activates key enzymes in the production of collagen, which is in turn allows the manufacture of connective tissue, bone, and cartilage. Manganese has also been shown to help in the prevention of carpal tunnel syndrome.
References: FREELAND-GRAVES, JEANNE H. "Manganese: An Essential Nutrient for Humans." Nutrition Today 23, no. 6 (1988): 13-19.