Exercise and Reaction Time


The problem we tested was the effect of exercise on reaction time. From previous knowledge we knew that increased heart rate produces adrenaline which prepares the body for fight or flight response and in addition causes pupil dilation. Increased pupil dilation is a defense strategy, to enable one to see farther, and a faster response to stimuli. We hypothesized that increased heart rate has an effect on reaction time.

            To test the hypothesis, we conducted a two-dependant test by comparing the reaction time of a subject at a resting heart rate and at an increased heart rate after exercise. In each trial, subjects were tested using a reaction meter. The subjects were asked to place their hand twelve inches away from the button, and react to the light going on by pushing the button underneath the light as quickly as possible. Only one light was used to keep consistency. Each subject had ten trials, and two tests, one before and one after exercise. Our prediction was that exercise would make reaction time faster due to increased pupil dilation.

            Our results indicated that increased heart rate did in fact have a significant effect on the reaction time. The average reaction time at resting heart rate was 0.6795 seconds, and the reaction time after the five minute aerobic workout was 0.5852 seconds. A T-test gave us a P-value of 0.00387923, which indicates that exercise does in fact have a significant effect on reaction time. As means to the explanation why, pupil dilation was also measured before and after exercise. At resting heart rate, an average of 5.3435 mm was recorded, and following the exercise, average dilation was 6.19875 mm. This increase of dilation resulted in an average of 0.85525 mm, and the significance is supported by another T-test with a P value of 0.002403307. Our hypothesis and predictions are supported by our data.

            According to a study done at the Graduate School of Sport Science, Osaka University of Health and Sport Sciences, in Osaka, Japan, results found that visual reaction time increased with acute exercise from that at rest. In this experiment by Ando S. et al. (2008), twelve participants were tested before and after using a stationary bike as an aerobic exercise. Other studies showed trends in reaction time do to arousal or state of attention. This state of attention also includes muscular tension that can be generated by exercise. Etnyre and Kinugasa et al. (2002) found that muscular tension allowed the brain to work faster, although muscular tension did not affect movement time. The study of Davranche et al. (2006) also showed similar results, concluding that exercise improved reaction time by increasing arousal. Though, numerous studies by Welford (1980), Broadbent (1971), and Freeman (1933), showed that reaction time deteriorates when the subject is either too relaxed or too tense. This study indicated that reaction time was fastest with an intermediate level o arousal.