Increased static postural sway after energy drink consumption: A randomized trial. [version 1; peer review: 2 approved with reservations]

Background: Energy drinks consumption continues to grow since its appearance in the United States in 1997. Available evidence indicates that caffeine, their main ingredient, can alter the central nervous system (CNS). However, it is unknown how energy drinks alter the CNS postural control mechanism. The purpose of this study was to investigate how energy drinks can affect postural control after sensory perturbations during stance.

Methods: 20 healthy adults, (11 males; 9 females) averaging 26.1 years of age, stood on a MatScan™ pressure mat, which measured center of pressure (CoP), anteroposterior (AP) and mediolateral (ML) postural sways during eight different balance tests (BALT’s). BALT's were designed to alter or cancel the systems involved in postural control: visual, vestibular and somatosensory. Subjects were randomly assigned to a caffeine group and an energy drink group. MANOVA analysis was performed for all variables of interest.

Results: In the caffeine group, the AP sway of the Eyes Closed test on a stable surface was statistically significant. In the energy drinks group, we observed a general tendency of participants to increase CoP slightly, AP and ML sway in most of the BALT’s after the consumption of an energy drink. However, this increase was not statistically significant. These results suggest that in healthy young adults, the sensory re-weighting mechanism can overcome postural perturbation and maintain overall postural control.

Conclusions: We observed an overall tendency to increase postural instability after the ingestion of energy drinks.