The shoulder is the most mobile joint in the body. Athletes are especially susceptible to shoulder issues because they can develop slowly through repetitive and intensive training routines.
Typically, an adult human head weighs between 10 and 12 pounds. As the head tilts or angles forward (in the case of looking at your cell phone), the neck muscles, tendons and ligaments support the head during movement and when static. The strain on your neck rises as the forward angle of your head increases.