A Cross Sectional Study - Effect of Postural Changes on Choice Reaction Time with Reference to Body Mass Index in Medical Students

BACKGROUND Reaction time (RT) is a simple, non-invasive means of estimating sensorimotor coordination and monitoring performance of an individual. The effect of body mass index (BMI) on RT, suggests that underweight, overweight and obese have increased RT as compared to normal BMI individuals. We wanted to compare the effects of supine, sitting and standing postures on RT and determine the influence of BMI on the same. METHODS An observational cross-sectional study was carried out over 2 months in the Department of Physiology on 60 medical students (30 males and 30 females). Visual and auditory choice reaction times of subjects were measured in supine, sitting and standing postures for green, red and yellow colours and high, medium and low frequency sounds. RESULTS In sitting posture, significant and moderate negative correlation was observed between BMI and visual reaction time (VRT) while the correlation between auditory reaction time (ART) and BMI was weak negative but non-significant. In standing posture, non-significant and weak negative correlation was observed between BMI and VRT, also the correlation between ART and BMI was weak negative but not significant. In supine posture, significant and moderate negative correlation was observed between BMI and ART while the correlation between VRT and BMI was weak negative but not significant. CONCLUSIONS When compared with normal BMI group, higher BMI subjects had longer visual as well as auditory reaction times. The difference was not found to be statistically significant though. A weak or moderate negative correlation between BMI and reaction time (r value < 0.4 in magnitude) was observed in three different postures. KEYWORDS Choice Reaction Time, Visual Reaction Time, Auditory Reaction Time, Posture, Body Mass Index