Savage, Ryland; Stevens, Andrew; Hicks, Joseph (Brigham Young University)
Faculty Advisor: Bailey, Bruce (Brigham Young University, Exercise Science)
Purpose: This study examined the effect of different intensities of exercise on subjective feelings of fatigue both immediately following exercise and after 60 minutes of intense cognitive testing in men and woman.
Methods: These results come from a secondary analysis of a larger randomized crossover study examining the different levels of exercise intensity on cognitive performance. We recruited 228 men and woman to participate in the study. Each participant was tested after three exercise conditions: moderate (35% VO2 max), vigorous (70% VO2 max), and sedentary (no exercise). Each exercise condition was randomized and each test was separated by one week. After each 40-minute exercise condition, we administered a visual analog scale to evaluate subjective feelings of fatigue. This assessment of fatigue was delivered before treatment, immediately after treatment and then again after a variety of cognitive tasks were performed for the duration of one hour.
Results: For the sedentary condition, feelings of fatigue increased after the 40-minute intervention (p<0.001) and decreased after 60 minutes of cognitive work but remaining elevated compared to baseline (p<0.01). For the moderate condition, feelings of fatigue did not change immediately after exercise (p=0.063) but then increased after 60 minutes of cognitive work (p<0.001). For vigorous condition, feelings of fatigue increased after exercise(p<0.001) and remained elevated after performing the cognitive tasks (p=0.163). Following the 40-minute intervention, fatigue was highest after the sedentary condition, followed by the vigorous condition and did not change after completion of the moderate condition. Following 60 minutes of cognitive work, fatigue was highest in the vigorous condition (p<0.001) and did not differ between the sedentary and moderate conditions (p=0.063).
Conclusion: The results of this study show that moderate exercise has no significant impact on feelings of fatigue but exercise at a higher intensity and being sedentary increase fatigue. Doing cognitive work increases fatigue if exercise precedes the tasks but being sedentary beforehand decreases feelings of fatigue during cognitive tasks. This suggests cognitive work is usually draining, but if performed after sedentary or low activity states such as watching TV, cognitive work will be invigorating and help feel more alert.