Nicholas Randall and Michael Larson, Department of Psychology
Sedentary lifestyle and obesity are growing concerns that are responsible for at least 300,000 premature deaths and $90 billion spent on health care per year in the United States (Manson et al., 2004). Many jobs today contribute to a sedentary lifestyle by requiring prolonged periods of sitting. Recent studies show that breaks in sedentary time results in less metabolic risk and a smaller waistline (Healy et al., 2011). Treadmill desks (desks that enable individuals to walk at a slow speed while working) along with cycling desks (workstations where individuals can cycle at a slow speed while working) have been shown to combat sedentariness and obesity through an increase in physical activity and weight loss (Koepp et al., 2013). While many studies have focused on the effects that treadmill desks can have on an individual’s overall health, few have included the concurrent effects on cognitive performance. In one study, neither response time nor accuracy tests of executive function were negatively affected during slow walking on a treadmill desk relative to sitting (Alderman et al., 2014). In contrast, several studies show that multitasking harms performance on both memory tasks and reading comprehension (Pool et al., 2003). Few studies have directly compared the effects of treadmill desks with those of cycling desks on cognitive performance. Our study aims to determine if there is a significant difference between treadmill and cycling desks by testing cognitive performance outcomes on randomized groups compared to baseline performance at a seated position. Increasing our understanding of how slow walking or cycling can affect cognitive performance has important implications for the integration of treadmill or cycling desks into the workplace and the possible effects on cognitive functioning. While they may offer various health benefits, our aims are to determine if treadmill and cycling desks impair performance and to clarify the specific health advantages. If we can understand how performance is influenced by simultaneous slow walking or cycling, then we can consider whether treadmill or cycling desks are generally helpful to a worker or not. By comparing cognitive function test results of an individual when seated with results when slow walking or cycling, our study is one step closer to determining if treadmill and/or cycling desks are beneficial to the workplace. The question of whether the health benefits from using a treadmill or cycling desk are worth the cognitive changes experienced while walking or cycling still needs to be answered.
Healthy adults (N=44, 26 female, 18 male), age 21±2, recruited from undergraduate psychology courses participated in two days of testing, a seated session, and an exercise session. All participants performed tests seated at a desk during the first session. The same tests were performed during the second session, but instead of seated, participants were either slowly walking (1.5 mph) at a treadmill desk, or slowly pedaling (7 mph) at a cycling desk. Participants were randomized to either the treadmill group (10 female, 8 male) or the cycling group (16 female, 10 male). Four tests were used to measure cognitive performance. The Rey-Auditory Verbal Learning Test (AVLT) was used as a measure of list-learning memory, consisting of word recall from two 15-item word lists. A math test was administered using the Paced Auditory Serial Addition Test (PASAT). Participants were asked to sum numbers from 1 to 9 presented them in an audio recording in four separate series of 25 trials each. A typing test was administered over a period of 10 minutes to assess a participant’s typing speed and accuracy. The final test, a flanker task, measured the response time of the participant. During the flanker task, the participants were instructed to respond as quickly and accurately as possible with their index finger if the middle arrow points left and with their middle finger if the arrow points right. Congruent (e.g., <<<<<) and incongruent (e.g., <<><<) stimuli were presented on either side of the target arrow. These four tests were performed during both the seated session and the treadmill or cycling session. At the beginning of the second session, participants were given five minutes of time to accustomate to the treadmill or cycling desk.
Statistical analyses were completed using a 2-Group (treadmill, cycling) x 2-Time (pre, post) repeated measures analysis of variance (ANOVA). For the PASAT total correct, there was a significant main effect of time, F(1,42)=55.3, p<.001. Both groups performed better at post-test relative to pre-test. There were no interactions or main effects of group (all ps>.05). For memory on the AVLT total learning, there was a main effect of time, F(1,42)=5.3, p=.03, both groups performed worse at post-test than pre-test. Similar to the PASAT, there were no main effects or interactions for group (ps>.05). At 30-minute delay, the main effect of group was still present with worse retention at post-test for both groups, F(1,42)=27.8, p<.001. There were no effects of group (ps>.05). For accuracy-adjusted typing speed (i.e., net typing speed), there was a significant main effect of time, F(1,42)=9.0, p=.005; however, group had no effect (ps>.05). Finally, for the flanker task we added the additional level of congruency (i.e., congruent vs. incongruent trials). For reaction times (excluding error trials), as expected, there was a main effect of congruency, F(1,42)=336.7, p<.001, with longer RTs to incongruent than congruent trials. Similarly, there was a main effect of time, F(1,42)=78.4, p<.001, with faster RTs at pre than post-test. Interestingly, there was a Time x Congruency x Condition interaction, F(1,42) = 4.6, p=.04. This interaction was driven by a significant between-groups difference at post-test for congruent trials only, t(42)=2.3, p=.03. For accuracy, the pattern of results was the same, except the Time x Congruency x Condition interaction was not quite significant, F(1,42)=3.6, p=.06.
Discussion and Conclusions
Overall, our findings show differences from the seated condition (pre-test) to the experimental conditions (post-test) that differed as a function of task type. Specifically, for memory tests performance on both the learning trials and the 30-minute retention went down when participants used the bike or treadmill desks. Notably, however, the decrease in performance was similar between groups. For measures of cognitive flexibility and processing speed (PASAT and flanker task), there was improvement from baseline to experimental conditions. It is likely that this improvement represents simple practice effects, as both the PASAT and the flanker are identical at both testing sessions, while the AVLT uses alternate forms. Finally, for typing performance, net-speed improved over time, but treadmill versus bike desk did not influence the results. Thus, taken as a whole, these data suggest that treadmill versus bike desks do not show significant differences and are not wholly detrimental to performance. Given the potential health benefits of walking or cycling during work, the absence of considerable detriments to cognitive performance would seem to suggest that using these alternative workstations is beneficial to employees. That said, the sample in this study is small and increased sample size and future replication efforts are needed. We plan to continue collecting data until we have over 100 participants. Then we will re-analyze and submit our findings to a journal interested in workplace health and cognitive performance.
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