Abstract
This paper examines the effects on mental fatigue of changes in the intensity of physical activity. An ergometer-equipped bicycle was used to attain three levels of physical activity: 20% below AT (where no muscular fatigue occurs), AT, and 20% above AT (where muscular fatigue occurs). As an indicator of mental fatigue, scores obtained in addition tests administered before and one hour after physical activity at each intensity level were used. The results of these tests showed that mental fatigue decreased after physical activity at 20% below AT, increased after physical activity at AT, and underwent no change after physical activity at 20% above AT, where AT is the level below which long periods of activity can be sustained. These results demonstrate that physical activity at a level easily sustained for a long period of time can lower mental fatigue, suggesting that the intensity of physical activity must be selected carefully.
