Effect of urban trips on stress and cognitive performance, a study in Bogota, Colombia

Introduction: Urban commuting can be a stressful experience and may impact cognitive function, a key component of overall health. The purpose of this study was to explore whether the cognitive performance of adults is differentially affected by stress resulting from commuting to study by public transportation or by bicycle in Bogota, Colombia. Methods: We designed an experiment in which stress and cognitive performance were systematically measured in seven participants, in triplicate, on separate days, before and after a trip by either public transportation or bicycle (total 6 trips). All participants were asked to complete a Stmop test and provide saliva samples before and after the trips. After-versus-before trip differences in salivary cortisol, weighted time-Stroop and percentage of success in the Stmop were compared between modes by a two-way analysis of variance (ANOVA) using mode of transport and participant as fixed factors. Results: The mean change in adjusted Stroop time was similar between modes (1,392 +/- 8,379 for bicycle, 889 ms +/- 6,675 ms for public transport, p = 0.85). The same occurred with the mean change in the percent of success in the Stroop test (1.39%+/- 5.16% for bicycle, -0.59 +/- 5.79% for public transport, p = 0.83). For percent successes in the Stmop, the p-value for the participant*mode term was p = 0.051. The mean change in salivary cortisol was -0.39 +/- 1.69 ng/mL for bicycle and -1.02 +/- 1.97 ng/mL for public transport (p = 0.11). The term associated with interindividual variability in change in cortisol was significant (p = 0.001). Conclusions: Commuting by bike or public transport induced a comparable effect on biological stress and cognitive performance. It is well-known that biking imparts many positive societal and health effects. Our results additionally show that despite involving physical effort, biking does not induce a larger biological stress response than public transportation.