kinesiology

Discussion

The purpose of this study was to examine the acute effects of aerobic exercise, resistance exercise, and a non-exercise control on measures of AA and cognition in eighth-grade adolescents. Results supported the primary hypothesis that acute exercise has the potential to improve mean math test scores compared to non-exercise. Specifically, acute resistance exercise showed the greatest improvement in math scores as compared to aerobic and non-exercise conditions. To the authors’ knowledge, such findings are novel in that they mark the first time acute resistance exercise has demonstrated positive influence on AA in a middle-school aged sample. Aerobic exercise also improved mean math score by an average of 0.44 points (out of 10), and while this result was not statistically significant, the authors believe an argument could be made that such an increase is indicative of practical significance (η2 = .04)[19]. Comment by Andrew Harveson: Re-statement of purpose and results/key findings. The following sentences into the second paragraph go into a bit more depth on the specifics of the findings.

Our secondary study purpose was to identify the acute effects of varying exercise types on cognition in eighth-grade students. Similarly to what was seen with AA, cognitive performance as measured by the Stroop Dot, Word, and Color tests was significantly enhanced following resistance exercise as compared to aerobic exercise and non-exercise. Again, to the authors’ knowledge, such a result is a novel finding in a middle-school aged sample. To date, the cognitive benefits of acute resistance exercise have been demonstrated in high-school students [20], college students [9], as well as adult [8] and elderly subjects [21], indicating that there may be some unique mechanisms at play with the modality of resistance exercise and its ability to positively influence AA and cognition. It is the hope of the authors that such findings will provide added justification for the inclusion of resistance exercise as an exercise modality that can be used to improve middle-school students’ academic performance and health simultaneously.

While the study of exercise and its influence on the brain has been studied for quite some time, it is only recently that in-depth examination of mechanisms involving acute exercise and its impact on AA and cognition have been explored. Despite the growth that is still occurring in this field of research, several hypotheses have been identified in previous literature that could offer insight into the findings illustrated in the present study. It is the authors’ belief that the neurotrophic-stimulation hypothesis elucidated by Hillman et al. [22] is most applicable to our findings. This hypothesis states that neuromuscular activity stimulates areas of the brain that control executive function, resource allocation, and speed of processing. In light of the notable neuromuscular adaptations that take place following a regular resistance exercise routine, especially in its early stages [23], it is within reason to conclude that this hypothesis best explains why resistance exercise notably improved AA and cognitive performance over a more traditional aerobic exercise protocol and the non-exercise control. Further, acute resistance exercise has previously demonstrated an ability to significantly increase brain-derived neurotrophic factor (BDNF) [24], which is known to play a significant role in neuroplasticity [25]. Similarly, previous research indicates that the more complex nature of acute resistance exercise, as compared to more traditional aerobic exercise such as walking or jogging, may play a significant role in elevating cognitive response. Ozkaya et al. [21] found that cognition, as directly measured by event-related potentials (ERP) in the brain, was enhanced to a greater degree by resistance exercise as compared to both aerobic exercise and non-exercise. The authors postulated that the complexity of the resistance exercise tasks caused participants to employ greater attention to external stimuli, which up-regulated neurocognitive signaling. The sum of current evidence related to brain function supports the above theories and should not be disregarded as educators seek new ways to maximize student performance in the classroom. Comment by Andrew Harveson: These paragraphs explain the mechanisms believed to have caused the results seen, as well as comparing current results to past findings.

Finally, it would be remiss not to include the cerebral blood-flow hypothesis as a potential mechanism that could potentially explain findings of the present study. The cerebral blood-flow hypothesis states that during moderate exercise intensities of up to 60% VO2max, the brain experiences an increase in blood flow and accompanying nutrients that positively enhance cognitive performance [26]. Such a mechanism should theoretically have enhanced AA and cognition similarly following both acute resistance and aerobic exercise in the present study, which were programmed at moderate intensities. It is also feasible that truly significant brain benefits are seen via synergism between increased cerebral blood flow and the neurotrophic factors identified previously. Additional research should look to isolate the precise mechanisms that drive improvements in executive function that are consistently seen throughout the current body of research surrounding acute exercise.

Findings from the present study are certainly encouraging to those advocating the need for increased levels of physical activity in today’s schools. However, this study was not without its limitations, which must be noted. Likely, the most significant limitation was the absence of a precise measure of intensity during the exercise protocols. Student-reported RPE was collected during each bout of exercise, and while there were no statistical differences in RPE between protocols (F1,61 = 2.76, p = .102), it is possible that aerobic and resistance exercise were not precisely matched for intensity. Given the previously stated influence of cerebral blood flow on cognitive function, such a limitation could skew results. Further, while the non-exercise protocol was based on past research, affect and arousal level were not directly measured, which could have potentially had a small influence on our results. An additional limitation of this study was the unequal representation of boys and girls. While it would have been desirable to have a representation that more closely matched the student body as a whole, the PE classes that were made available for sampling were comprised primarily of boys. Future study should aim to more closely match the representation of sexes in order to minimize potential confounding variables. Comment by Andrew Harveson: Limitations and recommendations for future research

Conclusions

In conclusion, results of the present investigation indicate principally that acute resistance exercise can positively enhance AA in standardized math tests and cognition, as measured by the Stroop test, respectively. These findings are unique in that they are the first known, published examples of acute resistance exercise augmenting specific executive functions in an eighth-grade sample. Such findings should be used to encourage greater amounts and varieties of physical activity in the modern school system with hopes that the immediate and lifelong benefits for student health and academic performance can best be realized. Comment by Andrew Harveson: Concluding paragraph summarizes the paper. Look to answer “what was found and why does it matter?”