持続的運動負荷が運動イメージ想起能力に与える影響について検討した．対象は下肢に整形外科疾患の既往のない健常成人13名とした.20mシャトルランテストによる持続的運動負荷を行い、その前後において，運動イメージ誤差（心的時間と実際動作時間の差）とPremotor time，最大随意収縮時筋トルク値，集中力（VAS）を測定し比較した．結果，運動イメージ誤差は運動負荷前後で有意な低下を認めなかった. Premotor timeは負荷前後で有意な低下を認めなかったが，最大随意収縮時筋トルク値とPremotor time測定時の集中力は有意な低下を認めた．本研究で用いた持続的運動負荷により一時的な身体疲労を生じていたが，運動イメージの正確性に変化が生じるほどの心的疲労は生じなかったと考える．運動イメージの正確性の変化には一時的な疲労ではなく長期的な身体疲労が関与する可能性が推測された．
Sports injury often causes by physical condition in the end of practice and game as continuing exercise because fatigue affects the neuromuscular system and neuromuscular control. One index of fatigue is muscle reaction time, particularly premotor time, which reflects central nervous system processing. Shorter premotor time significantly correlates with a high level of performance in sports and is important for quick judgment and movement. Motor imagery can be related to movement as well as premotor time, and mental chronometry is used to compare motor imagery duration with actual duration; high motor imagery ability is defined both times are similar. Few studies have examined the association between mental chronometry and fatigue. Then, we investigated whether continuous exercise loading affects motor imagery ability (difference between motor imagery and actual duration). Thirteen males with no orthopedic disorders were participated in this study. Motor imagery ability, premotor time, muscle torque at maximal voluntary contraction, and concentration (visual analog scale score) were evaluated before and after continuous exercise loading using the 20-m shuttle run test (SRT). Exercise intensity of 20-m SRT was 69% of the maximal oxygen consumption (V0₂max) in this study. Motor imagery ability and premotor time were not significantly different before and after continuous exercise loading. However, muscle torque and concentration were significantly different before and after continuous exercise loading. The 20-m SRT induced contemporary physical fatigue, as determined by exercise intensity, muscle torque at maximal voluntary contraction, and concentration, but no mental fatigue, as indicated by motor imagery accuracy. Physical fatigue increases signals from the brain to the muscle and compensate performance, but prolonged physical fatigue can't follow them. We indicate that long-term fatigue may cause a change in accuracy of motor imagery not short-term fatigue.