Exercise and diet is the best way to help a pit bull gain muscle mass. Choose exercises that conditions the dog's muscles.
Feeding a pit bull a proper diet and allowing them to be active will help it build muscle mass safely and healthfully. Playing fetch is a fun way for the dogs to build muscles as the quick exertion of energy build muscles. This especially works if it is running up hill to fetch the toy. Spring poles can be installed for the dog to play with. This allows it to leap and hang, which builds the muscle mass. Pairing the exercise with a high-protein diet is sure to gain the muscles a pit bull needs.