Based on the general theme of conservation, which of the following is most likely to happen if an athlete breaks his arm and must wear a cast and not use that arm for six weeks? Based on the general theme of conservation, which of the following is most likely to happen if an athlete breaks his arm and must wear a cast and not use that arm for six weeks? The muscles in the other arm will get stronger in order to help out. Muscles in the injured arm will get smaller because they are not being used. The muscles in the injured arm will not change—only the bone was broken. The muscles in the injured arm will get stronger to compensate for the injured bone.