In developing a senior lecture for the 2014 national meeting of the North American Society for the Psychology of Sport and Physical Activity, I had the opportunity to reflect upon a career of research and to focus on three interesting questions that my colleagues and I have attempted to address. These questions have led to several studies that all revolve around identifying ways to increase the effects of exercise on cognitive performance. In particular, the questions examine the possibility of increasing effects by focusing on particular populations (e.g., older adults, children) and by increasing our understanding of dose-response relationships between exercise parameters (e.g., intensity, duration) and cognitive outcomes. I present empirical evidence relative to each of these questions and provide directions for future research on physical activity and cognitive functioning.
Jennifer L. Etnier
Alzheimer's disease is a chronic illness characterized by clinical cognitive impairment. A behavioral strategy that is being explored in the prevention of Alzheimer's disease is physical activity. Evidence from randomized controlled trials (RCTs) testing the effects of physical activity for cognitively normal older adults supports that physical activity benefits cognitive performance. Evidence from prospective studies supports a protective effect of physical activity with reductions in the risk of cognitive decline ranging from 28% to 45%. RCTs with cognitively impaired older adults also generally support positive effects with greater benefits evident for aerobic interventions. Research examining the potential moderating role of apolipoprotein E (APOE) has yielded mixed results, but the majority of the studies support that physical activity most benefits those who are at greatest genetic risk of Alzheimer's disease. Future directions for research are considered with an emphasis on the need for additional funding to support this promising area of research.
Jennifer L. Etnier
Jennifer Gapin and Jennifer L. Etnier
Children with attention-deficit hyperactivity disorder (AD/HD) consistently perform worse on executive function (EF) tasks relative to those without AD/HD. Physical activity has a small effect on cognition in children and may be particularly beneficial for children with AD/HD by impacting fundamental EF deficiencies that characterize this disorder. The purpose of this study was to explore the extent to which physical activity is associated with EF in children with AD/HD. Eighteen boys (M age = 10.61, SD = 1.50) with AD/HD were recruited to complete four EF tasks. Physical activity was measured with an accelerometer that provided daily minutes of moderate-to-vigorous intensity physical activity; this measure was a significant predictor of performance on the Tower of London planning task, adjusted R 2 = .28, F(1, 16) = 7.61, p < .05, and was positively associated with other EF measures. These results suggest that higher physical activity is associated with better EF performance in AD/HD children.
Jeffrey D. Labban and Jennifer L. Etnier
Evidence supports that acute exercise benefits long-term memory. However, it is unclear whether these effects are due to benefits to encoding or consolidation. The purpose of this study was to more effectively isolate encoding and consolidation to advance our understanding of the specific nature of the effects of exercise on long-term memory. Using a within-subject design, participants completed a control session (no exercise), an encoding and consolidation condition (exercise prior to exposure to the memory task, E + C), and a consolidation condition (exercise following exposure). The exercise was 30 min of moderate-intensity cycling. Memory was assessed using the Rey Auditory Verbal Learning Test with recall assessed at 60 min and recall and recognition assessed at 24 hr. Results showed that the E + C condition had significantly better recall at 60 min and 24 hr than the no-exercise condition. This provides additional evidence that acute exercise benefits encoding more than consolidation.
SeYun Park and Jennifer L. Etnier
Background: Evidence supports that a single session of exercise has benefits for cognitive performance following exercise. Although the vast majority of research has been conducted with young adults, very few studies to date have tested these effects in adolescents (high school aged students). As executive function (EF) develops through late adolescence and into young adulthood, it is important to assess the extent to which acute exercise benefits EF in adolescents. The primary purpose of this study was to assess the effect of moderate-intensity acute exercise on subsequent EF performance in this population. Methods: Healthy high school students (N = 22; age: 15.90 [0.29] y) volunteered to participate in the study. Using a within-subjects design with order of conditions randomized and counterbalanced, participants performed the Stroop Test, the Symbol Digit Modalities Test, and the Tower of London Test following control and following exercise with sessions performed on different days. Results: Exercise resulted in significant benefits for Stroop Color, Stroop Color-Word tests, Symbol Digit Modalities Test, Tower of London total moves, and Tower of London total excess moves. Conclusions: These results provide an important extension to the literature by confirming that 20 minutes of moderate-intensity exercise benefits EF performance in high school students.
Jennifer L. Etnier and Yu-Kai Chang
The purpose of the present commentary is to introduce relevant issues with respect to the measurement of executive function in physical activity studies. Suggested definitions of executive function are introduced, and executive function tasks that are commonly used in the neuropsychological literature are presented and briefly described. The extant literature on physical activity and cognition is discussed, and issues relative to the limitations of this body of literature are raised. In summary, research on the effect of physical activity on executive function is still in its infancy. We encourage researchers in this field to provide a clear definition of executive function, to carefully consider the relevance of published effect sizes to their own research questions, and to consider either providing a logical rationale for their selection of particular executive function measures or to use multiple measures of executive function when exploring relationships between physical activity and executive function.
Yu-Kai Chang and Jennifer L. Etnier
The purpose of this study was to explore the dose-response relationship between resistance exercise intensity and cognitive performance. Sixty-eight participants were randomly assigned into control, 40%, 70%, or 100% of 10-repetition maximal resistance exercise groups. Participants were tested on Day 1 (baseline) and on Day 2 (measures were taken relative to performance of the treatment). Heart rate, ratings of perceived exertion, self-reported arousal, and affect were assessed on both days. Cognitive performance was assessed on Day 1 and before and following treatment on Day 2. Results from regression analyses indicated that there is a significant linear effect of exercise intensity on information processing speed, and a significant quadratic trend for exercise intensity on executive function. Thus, there is a dose-response relationship between the intensity of resistance exercise and cognitive performance such that high-intensity exercise benefits speed of processing, but moderate intensity exercise is most beneficial for executive function.
Jennifer L. Etnier and Daniel M. Landers
The primary purpose of this study was to examine differences in performance on fluid and crystallized intelligence tasks as a function of age and fitness. A secondary purpose was to examine the influence of age and fitness on the beneficial effects that practice has on both performance and retention on these tasks. Fitness was assessed in 41 older and 42 younger participants who were then randomly assigned to either experimental or control conditions. Participants performed repeated trials on two cognitive tasks during acquisition and retention, with the experimental group practicing for 100 trials and the control group practicing for 20 trials. Older participants performed better than younger participants on the crystallized intelligence task: however, younger participants performed better than older participants on the fluid intelligence task. On the fluid intelligence task, older fit participants performed better than older unfit participants. Learning did occur on the fluid task and differed as a function of age and fitness. Learning did not occur on the crystallized task.