Too much stress -- or too many fastballs -- can cause partial tears and swelling in the tendons of the rotator cuff. Abrupt stress may even cause one of the tendons to pull away from the bone or tear in the middle of the tendon.o diagnose a rotator cuff tear, your doctor will give you a thorough physical exam. He or she will want you to move your arm in different directions to see what causes pain. In addition, your doctor might want to order the following tests: 1  X-ray of the shoulder with some special views.
In rare cases, generalized muscle weakness may be caused by another health problem, such as: 1  A problem with the minerals (electrolytes) found naturally in the body, such as low levels of potassium or sodium. 2  Infections, such as a urinary tract infection or a respiratory infection.
Leg weakness can occur as part of a generalized feeling of weakness all over your body, or it may develop in one or both legs. True weakness occurs when the muscles lose their strength, but people often perceive that their muscles are weak when they feel ill or tired. In these cases there is not a true loss of muscle function.