Tendonitis can be caused by a variety of factors. Typically, acute tendonitis results from repetitive stress and overuse of a muscle. This is common in activities like tennis and golf, where players repeatedly swing or compensate for another injury, leading to ongoing stress on the muscle.    

This condition can negatively impact daily life by making simple tasks difficult, such as opening a jar, lifting items from the refrigerator, or emptying the dishwater. Reaching and other repetitive activities often exacerbate the issue. In the past, people typically managed tendonitis by resting and then gradually returning to activity. However, this can sometimes lead to muscle tendonitis, as the repetitive movements that caused the problem in the first place are reintroduced.