For many, physical exercise is an important part of everyday life, and research has shown that exercise has positive effects on physiological and psychological health (Zoeller, 2007; Manca, 2006). 

More research exists for chronic exercise (many exercise sessions over time) than acute (a single exercise session). However, clinically, acute exercise may be notably valuable to our field as a short-term facilitator for cognitive and linguistic rehabilitation (Faroqi-Shah & Crossman, in prep.) 

What does the literature say? 

Overall, acute cardiovascular exercise (cycling, treadmill running, etc.) has shown to have a small positive effect on cognition lasting up to two hours post-exercise (Chang et al., 2012) leaving a feasible timeframe for intervention. Moderate-intensity exercise, as opposed to low or high intensity, has shown to yield greater positive effects (Chang et al., 2012, Davaranche et al., 2006; Faroqi-Shah et al., in prep). 

The mechanism(s) by which exercise improves cognition remain debated among researchers. Two predominant schools of thought that were investigated in our current study include the “arousal theory”” or speed hypothesis (Tomporowski & Ellis, 1986) and the “inhibitory theory” (Lambourne & Tomporowski, 2010). The arousal theory states that exercise improves neural conduction and thus processing speed (Tomporowski & Ellis, 1986). Behaviorally, this would manifest as shorter reaction times during experimental tasks. The inhibition theory, which proposes improved connectivity of frontal inhibitory networks in the brain, would be supported by improved performance on behavioral tasks of inhibition, such as Stroop or Flanker, as a result of exercise (Lambourne & Tomporowski, 2010).

More acute exercise research exists in younger adults than older adults, and the literature is mixed in nature.  That is, some researchers have found improved speed as a result of acute cardiovascular exercise (Chang, Chu, Wang, Song & Wei, 2014; Barella, Etnier, & Chang, 2010) and some have not (McMorris & Keen, 1994). Similarly, some have reported improved inhibitory control (Won et al., 2019) and others have not successfully replicated these effects (Chang et al., 2014; Barella et al., 2010). 

To our knowledge, no published research exists regarding the linguistic effects of exercise on older adults. Faroqi-Shah, Fuchs & Powers (in prep) investigated the cognitive and linguistic effects of twenty-five minutes of cycling on college-aged adults and found improvements in both general cognitive and linguistic speed, but not in general cognitive or linguistic inhibition, as a result of exercise. 

How may exercise impact cognitive and linguistic function in older adults in terms of inhibition and speed? 

The current study utilized a similar acute-exercise paradigm to that used in the previous Faroqi Shah et al. (in prep) study to investigate the effects of twenty-five minutes of acute cycling on domain-general cognition and language in terms of speed and inhibition in older adults (58-75). Four computerized tasks were used pre and post-exercise and during a sedentary control condition. Heartrate and perceived exertion measures (Borg, 1982) were used to evaluate exercise exertion. 

Speed: We predicted that older adults would show improvements in domain-general and linguistic speed seen in younger adults as measured by shorter reaction times (Faroqi-Shah et al., in prep). 

Inhibition: We predicted that older adults would show improvements in domain-general and linguistic inhibition (measured by smaller interference effect on the Stroop task and shorter reaction times on a test of linguistic inhibition, respectively) not seen in younger adults (Faroqi-Shah et al.) based on research showing improved inhibitory control as a result of exercise (Won et al., 2019) in older adults specifically. 

Age Effects: We predicted that older adults would show greater improvements in domain-general and linguistic speed and inhibition compared to younger adults (data derived from Faroqi-Shah et al.’s younger adult study) as a compensation for age-related decline in processing speed (Salthouse, 1996), inhibitory control (Dempster, 1992), and language (Thornton & Light, 2006). 

*Our alternative hypothesis for these questions was that exercise effects would not be strong enough to overcome decline in processing speed (Salthouse, 1996), in inhibitory control (Dempster, 1992), and in language (Thornton & Light, 2006) that have been reported in healthy aging older adults*

What did we find? 

  1. Processing Speed

Figure 1. Processing speed as a function of experimental condition and time  

Text Box: Reaction Time (ms)
*=statistically significant, p<0.05

For domain-general processing speed, measured using a simple reaction time task, results are as follows: 

  • significant main effect of condition indicating faster pre and post reaction times in the control condition (watching a video) compared to the exercise condition
  • significant main effect of time with no interaction between condition and time, indicating a within-session practice effect was responsible for shorter post-session RTs for both conditions rather than true exercise effects. 

Figure 2. Stroop effect as a function of experimental condition and time 

Text Box: Stroop Effect (ms)
*=statistically significant, p<0.05

For domain-general inhibition, measured using the Stroop task, results are as follows: 

  • significant main effect of time with no interaction between condition and time, indicating a within-session practice effect was responsible for shorter post-session RTs for both conditions rather than true exercise effects.
  • Language:
  • Lexical Speed 

Figure 3. Lexical decision as a function of experimental condition and time 

Text Box: Reaction Time (ms)
*=statistically significant, p<0.05

For lexical processing speed, measured using simple reaction times from a word recognition task, results are as follows: 

  • significant main effect of condition indicating faster pre and post reaction times in the control condition (watching a video) compared to the exercise condition
  • significant main effect of time with no interaction between condition and time, indicating a within-session practice effect was responsible for shorter post-session RTs for both conditions rather than true exercise effects. 
  • Lexical Inhibition 

Figure 4. Picture verification as a function of experimental condition and time 

Text Box: Reaction Time (ms)
*=statistically significant, p<0.05

For lexical inhibition, measured using simple reaction times from a word retrieval task containing semantic distractors, results are as follows: 

  • significant main effect of time with no interaction between condition and time, indicating a within-session practice effect was responsible for shorter post-session RTs for both conditions rather than true exercise effects. 
  • Age-Related Effects

For each of the three computer tasks completed by both the young and old adult groups (Domain-General Speed, Domain-General Inhibition, and Lexical Speed) during the exercise condition we found a significant main effect of group, indicating younger adults performed significantly faster on all tasks during pre and post sessions. 

We also found a significant main effect of time for all tasks, indicating within-group practice effects for both age groups. 

For Domain-General Inhibition (Stroop task) we did find a significant interaction between group and time (see below) indicating greater exercise effects in the older adult group for this task. However, as there was no exercise effect when examining older adults alone for this task (see Question 2 above) this was interpreted as greater within-session practice effect for older adults rather than true exercise effect. 

Figure 5. Stroop effect as a function of group and time *

Text Box: Stroop Effect (ms)
*=statistically significant, p<0.05

What does this all mean? 

In this group of active, community-dwelling older adults our acute cycling paradigm did not improve cognitive or linguistic function beyond that of general practice effects. These findings contrast findings in younger adults that indicate acute exercise-induced improvements in cognitive and linguistic speed. Older adults performed significantly slower than their younger counterparts on all experimental tasks. Therefore, it is likely that exercise effects are too small to overcome decline in processing speed (Salthouse, 1996), inhibitory control (Dempster, 1992), and linguistic processing (Thornton & Light, 2006) associated with healthy aging. 

Exercise effects present in this population are not robust enough to emerge after a single twenty-five-minute exercise session, indicating a single bout of acute exercise will likely not augment rehabilitation effects in older adults with cognitive and/or linguistic ailments. Due to the scarcity and mixed nature of the available literature, future research is needed in this area to solidify our claims and further explore clinical implications. 

References

Barella, L.A., Etnier, J.L., & Chang Y.K. (2010). The immediate and delayed effects of an acute bout of exercise on cognitive performance of healthy older adults. Journal of Aging and Physical Activity, 18, 87-98. 

Borg G.A. (1982). Psychophysical bases of perceived exertion. Medicine and Science in Sports and Exercise14,377-381.

Chang, Y.K., Chu, C.H., Wang, C.C., Song, T.F., & Wei, G.X. (2014). Effect of acute exercise and cardiovascular fitness on cognitive function: An event‐related cortical desynchronization study. Psychophysiology, 52(3). 342-351. doi: 10.1111/psyp.12364

Chang, Y.K., Labban, J.D., Gapin, J.I., & Etnier, J.L. (2012). The effects of acute exercise on cognitive performance: A meta-analysis. Brain Research, 1453(9), 87-101. https://doi.org/10.1016/j.brainres.2012.02.068

Davranche, K., Birle, B., Audiffren, M., & Hasbroucq, T. (2006). Physical exercise facilitates motor processes in simple reaction time performance: an electromyographic analysis. Neuroscience letters, 396(1), 54-56. 

Dempster, F. N. (1992). The rise and fall of the inhibitory mechanism: Toward a unified theory of cognitive development and aging. Developmental Review, 12, 45–75.

Faroqi-Shah, Y.,  Fuchs, L. & Powers, M. (in preparation). The effects of acute exercise on language and cognition: delineating speed and inhibitory effects.

Lambourne, K., & Tomporowski, P. (2010). The effect of exercise-induced arousal on cognitive task performance: A meta-regression analysis. Brain Res, 1341, 12-24. doi: 10.1016/j.brainres.2010.03.091

Manca, M. (2006). Physical activity exercise and cardiovascular health. British Journal of Sports Medicine, 40(10), 820. 

McMorris, T. & Keen, P. (1994). Effect of exercise on simple reaction times of recreational athletes. Perceptual and Motor Skills, 78(1). 123-130. doi: 10.2466/pms.1994.78.1.123

Salthouse, T.A. (1996). The processing-speed theory of adult age differences in cognition. Psychological Review, 103(3), 403–428. 

Thornton, R., & Light, L.L. (2006). Language comprehension and production in normal aging. 

Handbook of the Psychology of Aging, 261-287. 

Tomporowski, P.D., & Ellis, N.R. (1986). Effects of exercise on cognitive processes: A review. Psychological Bulletin, 99. 338-346. 

Won, J. Alfini, A.J., Weiss, L.R., Michaelson, C.S., Callow, D.D., Ranadive, S.M., … & Smith, J.C. (2019b). Semantic memory activation after acute exercise in healthy older adults. Journal of the International Neuropsychological Society, 25(6), 557-568. https://doi-org.proxy-um.researchport.umd.edu/10.1017/S1355617719000171

Zoeller, R. F. (2007). Depression, anxiety, physical activity, and cardiovascular disease: What’s the connection? American Journal of Lifestyle Medicine, 1(3), 175-180). doi:10.1177/1559827607300518

About the Author

Claire Crossman (MA ’20) completed this research at the University of Maryland using funding assistance from the MCM Research Fund. Claire is a graduate student in speech-language pathology whose research and clinical interests include neurogenic communication and swallowing disorders and fluency disorders.