Combating mental fatigue in soldiers

Mental fatigue impairs both cognitive performance and subsequent physical performance. Mental fatigue can be brought about by the prolonged performance of a single cognitive task, but also by the combined performance of many cognitively demanding activities, as well as tasks that require self-control or prolonged periods of suppressing emotion. Manifestations of mental fatigue include feelings of tiredness, lack of energy and exhaustion, as well as changes in mood states, towards moods such as irritation. Mental fatigue is further exaggerated by conditions commonly experienced by soldiers, such as sleep deprivation. As mental fatigue progresses, continuing a cognitive task becomes difficult, represented by aversion to continue with the present task, a decrease in the level of commitment to the task at hand and increased resistance against further effort. Anecdotal evidence has also noted that mentally fatigued persons become distracted more easily and that lapses in concentration become more frequent. Mental fatigue impairs physical performance, primarily through a reduction in endurance, as well as impacting technical performance, such as soccer passing and goal shooting. Despite consistent findings of a reduction in endurance with mental fatigue, a recent study reported that when compared with recreational cyclists, professional cyclists were more tolerant to mental fatigue. Following a bout of mental exertion, the time trial performance of the professional cyclists was unimpaired, they also significantly outperformed the recreational cyclists on the cognitive task designed to induce mental fatigue. It was suggested that the professional endurance athletes had a greater self-regulatory capacity compared to the recreational athletes, likely due to the amount of time they spend engaged in activities requiring self-regulation such as maintaining a strict diet, refraining from alcohol and committing to long individual training sessions. Although suggested to be partially genetic, many studies have shown that practice of one task of self-regulation will improve performance on another, unrelated task of self-regulation. Self-regulation is a characteristic required for successful performance of endurance sports, studying and training, and persisting with a cognitive task. Consideration of the impact of mental fatigue on physical performance is important in a Defence context. Individuals may be required to perform monotonous tasks for long periods of time, followed by, or concurrent to physical tasks, often with little to no rest. Here we discuss the impact of mental fatigue on physical performance and potential strategies to overcome these performance decrements.