Motor control is affected by subjective muscle fatigue and attention to the body (body-specific attention). Although voluntary hand movements immediately alter spatial attention, it is unclear whether these voluntary movements also alter body-specific attention to the hand. We aimed to determine whether voluntary hand movements and subjective muscle fatigue immediately affect body-specific attention to the hand. Nineteen healthy adults participated in this study. Body-specific attention to the left hand and subjective muscle fatigue were assessed before and after participants repeatedly moved their left hand to the palmar and dorsal sides. In the visual detection task measuring body-specific attention, participants responded rapidly to a light appearing on a real hand and a dummy hand. Body-specific attention was calculated by subtracting the reaction time of the real hand from that of the dummy hand. To assess subjective muscle fatigue, participants answered a question on an 11-point scale. Changes in body-specific attention were categorized into two groups: with and without muscle fatigue (p < 0.05). In the group without muscle fatigue, body-specific attention was higher after the movements than before (p < 0.05). Additionally, as muscle fatigue increased after the movements, body-specific attention decreased (r = − 0.568, p < 0.05). Our results showed that voluntary hand movements increased body-specific attention to the hand without subjective muscle fatigue, but decreased it with fatigue. These findings suggest that subjective muscle fatigue affects body-specific attention and consequently makes motor control more difficult. Our findings may provide new strategies and interpretations for rehabilitation therapy.
