RESUMO
BACKGROUND/AIMS: Physical exhaustion is not always peripheral, and it is the brain that causes the sensation of fatigue either due to decrease of metabolic resources or due to central activation process that regulates attention and performance. This study was undertaken to observe the variations in event-related potentials (ERPs) and cognitive performance after an exhausting physical exercise. METHODS: A total of 60 healthy young adult subjects were included in the study. The study was conducted in 2 phases with at least a week gap between the phases. The participants answered a Multidimensional Fatigue Inventory (MFI-20) questionnaire before and after trials in each phase to measure the induced physical exhaustion. In phase I (control trial), the ERP data were processed using P300, Standard auditory "oddball paradigm," on computerized evoked potential recorder (RMS EMG MK-2) using 10/20 system to know the engagement of attention after which participants were given to perform cognitive tasks such as "Stroop Test, Trial Making Test and Mini Mental State Examination." In Phase II (exercise trial), the participants were instructed to cycle as hard as they could, till they could not continue anymore, which was followed by recording of P300-evoked potentials and performance of cognitive tasks as in Phase I. Paired t test was used to compare between any dependent variables. RESULTS: Fatigue-related subjective measures (MFI-20) showed that both mental and physical exhaustion were significantly greater in the exercise-involved cognitive trial than in the control trial. Lower P300 latencies reflect faster reaction time; however, their response accuracies were poorer resulting in poorer cognitive performances. Participants subjected to control trial performed better in terms of higher percentage accuracy but with slow reaction time. CONCLUSION: The participants experienced more fatigue physically and mentally during the exercise that involved cognitive tasks. An apparent decrease in attention based on decreased percentage accuracy of response was evident, implying that fatigue, performance, and attention are interdependent.
RESUMO
BACKGROUND AND OBJECTIVES: An increase in the consumption of smokeless tobacco has been noticed among high school, college students, and adults. Despite the antiquity and popularity of chewing tobacco in India, its effects have not been investigated systematically in humans. The aim of this study was to investigate acute effects of gutkha chewing on heart rate variability (HRV) among healthy young adults. MATERIALS AND METHODS: A total of 60 young adult males were included in the study. Each individual was asked to chew tobacco and subjected to HRV analysis. HRV analysis using short-term electrocardiogram recording was used to measure HRV parameters before gutkha chewing and at 5, 15, and 30 min after chewing tobacco. One-way analysis of variance and paired t-test was used to assess changes over time. RESULTS: There was a significant increase in heart rate (HR) during tobacco chewing. Mean HR at baseline measured 73.0 ± 6.2 bpm. There was a rise in mean HR to 83.7 ± 9.1 bpm at 5 min during tobacco chewing and gradual reduction to baseline observed after 15 min followed by no significant change till 30 min. The normalized low-frequency power and LF/high-frequency (HF) power ratio were elevated after 5 min; however, normalized HF power was reduced after 5 min tobacco chewing. CONCLUSION: Gutkha is closely associated with traditional cardiovascular risk factors as detected by a transient enhancing sympathetic activity during tobacco chewing in the form of increased HRV parameters or an imbalance between sympathetic and parasympathetic neural activity among healthy young adults.