Focal dystonia, the dysregulation or temporary loss of motor control during musical performance, is a condition among musicians of unknown cause and without preventative measures. Some research suggests that focal dystonia is caused by pain and muscular fatigue, resulting in excessive afferent pathway input. However, this argument has not been sufficiently supported through experimentation. In this study, we investigate the hypothesized correlation between bodily over-exertion and left-hand finger pain, using a control group consisting of musicians absent symptoms of irregular muscle tension. Although a diagnosis of focal dystonia is not employed, musicians with symptoms of irregular muscle tension are the target group of study, as they are believed to be predisposed to developing focal dystonia. The aim of this study is to identify factors that lead to onset of focal dystonia. The methodology employed in this study involves the inclusion of 82 Japanese musicians who specialize in high-speed stringed instruments. Regarding left finger muscular tension, subjects were divided into an over-exertion group and a normal tension group. During a period of rest from musical practice, subjects were given a questionnaire evaluating the degree of left finger pain. Muscular tension was used as a response variable, and analysis was conducted to reveal any causal link. Results revealed a stronger tendency for muscular tension to persist in the over-exertion group compared to the normal group, even when musical training despite bodily fatigue was stopped. Left finger pain was also higher in the over-exertion group.