Mental fatigue may negatively influence exercise performance, according to a report in the Journal of Applied Physiology.As part of the study 16 participants rode a stationary bicycle to exhaustion under two conditions: once when they were mentally fatigued and once when they were mentally rested. The mental fatigue sessions began with a challenging 90-minute mental task that required close attention, memory, quick reaction and an ability to inhibit a response. The trials took place in the laboratory on different days. The participants got the same amount of sleep, drank the same amount and had the same meal before each of the sessions.

Throughout both exercise sessions, the researchers tracked a variety of physiological measures, such as oxygen consumption, heart rate, cardiac output, blood pressure, ventilation, and blood lactate levels.

Results revealed that the volunteers stopped exercising an average of 15% earlier when they were mentally fatigued. However, the study also found that mental fatigue did not cause the heart or muscles to perform any differently. So the difference in performance was due to “perceived effort.”

Journal of Applied Physiology – March 2009;106:857-64.

jap.physiology.org