Effect of Caffeine Dose on Postural Stability

Abstract

Caffeine is a well-defined neuro-stimulant that increases muscle firing rates and neuro-excitability, but more commonly is known as a stimulant that is found in many preworkout supplements used by the young adult population today. Injury risk has been shown to relate to a decrease in balance ability and the effect of caffeine on balance is understudied. PURPOSE: To measure the effect of caffeine on postural stability and balance in young adults. METHODS: Eleven female (n=8) and male (n=3) young adults (18-21 yrs old) performed 3 trails, conducted in randomized order, and separated by at least 48 hours. The trials consisted of ingesting either placebo or caffeine (3 (LC) or 6 (HC) mg/kg body weight) pills one hour prior to testing. Participants then completed three, twenty-second trials for each of the four balance tests performed on the Biodex balance system (BBS) at a stability level of 6: Postural Stability (PS; eyes open and eyes closed), and Athlete Single Leg (ASL) on both the right and left leg. Postural stability tests were performed first and in random order followed by the ASL tests, also performed in a randomized order. Balance index (BI) and balance standard deviation (BSD) scores were recorded from the BBS. Repeated measures ANOVAs were used to evaluate differences in measures between treatments. RESULTS: There were no significant differences between treatments for BI or BSD scores during either the eyes open or eyes close PS tests. There was a significant increase (p=0.02) in overall BSD score during the left-footed ASL between the placebo and HC (0.56 ± 0.05 and 0.74 ± 0.07, respectively). This difference was largely due to increased BSD in the anterior-posterior plane (0.69 ± 0.05 and 0.87 ± 0.07, respectively). No significant differences were found between treatments for BI (left- or right-footed) or right-footed BSD scores during the ASL. CONCLUSION: Caffeine had little effect on postural stability in young adults at rest. A significant decrease in stability was seen in the anterior-posterior plane during ASL on the left foot following the highest dose of caffeine; however, without significant decrements in any other measure and the small current sample size, these results need to be interpreted with caution.