Biceps tendinitis is most often the result of everyday wear and tear on the muscle. In terms of sports, weightlifting is one of the high risk activities for biceps tendinitis, but this condition is a common sports injury that can happen to pros and amateurs alike.
Over time and after many years of use, tendons begin to weaken. The protective layer that covers these connective tissues can thicken. So you may not even need to be an athlete to experience biceps tendonitis, it can also happen from normal wear-and-tear.
Source: Healthline