B-proteins and carbohydrates
The supplement has to build lean muscle and strengthen tendons and ligaments. Muscle, tendons, and ligaments are all made of protein. So the supplement must contain protein.
It should also provide energy. The most readily used form of energy is carbohydrates (for energy metabolism, carbs are used first, then lipids, then proteins as a last resort). Therefore, the supplement should have carbohydrates.
