Comparing the effects of physical and brain activity on perceptual and physiological responses: examining changes during and after exercise to the point of fatigue

Background and Aims: Fatigue resulting from physical and cognitive activities is one of the fundamental challenges in the fields of sports science and neuroscience, which can affect an individual's physical and psychological performance. The aim of the present study was to compare the effects of physical activity and brain activity on objective physiological responses (such as heart rate) and subjective responses (such as perceived exertion) during and after exercise to the point of exhaustion.

Materials and Methods: 20 female students aged 25 to 30 from Alzahra University were selected using purposive sampling. The research method of the present study was semi-experimental. Based on the inclusion criteria (being right-handed, having normal or corrected vision, physical and mental health, no heart problems such as palpitations, chest pain, or heart failure, and no prior familiarity with performing the task), they were divided into two groups: mental activity and physical activity (10 participants in each group). The Borg Physical Fatigue Scale, Mental Fatigue Scale, Stroop test, and Polar heart rate monitor were used to collect data. Physical fatigue, mental fatigue, and heart rate of participants in each group were recorded before the start of the activity, 5 and 10 minutes during the activity, immediately, and five minutes after the end of the activity. Results: The Borg Physical Fatigue Scale, Mental Fatigue Scale, Stroop test, and Polar heart rate monitor were used to collect data. Physical fatigue, mental fatigue, and heart rate of participants in each group were recorded before the start of the activity, 5 and 10 minutes during the activity, immediately, and five minutes after the end of the activity. The results of repeated measures analysis of variance showed that the heart rate and perceived physical and mental difficulty of participants in both physical and mental activity groups increased with increasing duration of physical or mental training (P=0.001). Comparison of the mean heart rate and perceived physical activity difficulty of the physical activity group in the assessment stages of the fifth minute, the tenth minute, the end of the activity and five minutes after the activity was higher than the mental training group, and the physical activity group had the highest mean heart rate and perceived physical activity difficulty in the tenth minute of activity and the end of the activity, but the mean decreased in the five-minute stage after the activity (P=0.001). The mean perceived difficulty of brain activity of the brain activity group in the assessment stages of the fifth minute, the tenth minute, the end of the activity and five minutes after the activity was higher than the physical activity group, and the mental activity group had the highest mean perceived difficulty of brain activity in the tenth minute of activity and the end of the activity compared to the physical activity group (P=0.001). Conclusion: In general, physical activity primarily increases physiological load, while cognitive activities lead to increased cognitive load and mental fatigue. Therefore, it is necessary to consider both physical and mental aspects in the design of training interventions to prevent early burnout and serious injuries.