There is substantial evidence that a single bout of exercise can improve cognitive functions and retention of certain types of declarative memory. However, it is unclear if a similar effect can be demonstrated when coupling physical activity with the acquisition and retention of a motor skill. Hence, the overall aim of the present thesis was to investigate the relationship between acute exercise and motor memory, with special interest in investigating if exercise performed after motor skill learning could improve skill retention. Study I was designed to assess if a single bout of exercise performed before or after acquisition of a novel motor task would improve long-term retention of the motor skill. Forty-eight young men were recruited to the study. The subjects were divided into three experimental groups. Two groups performed 20 minutes of intense bike ergometer exercise either before (PRE) or after (POST) training of a motor task, while a third group served as control group (CON). The subjects’ ability to perform the task was tested one hour, 24 hours and seven days after learning the task. Study I showed that PRE and POST both performed better than CON after 24 hours and seven days. Additionally, POST outperformed PRE after seven days, thus indicating that exercise affects the process during which the memory is consolidated more than learning itself. In order to investigate if the behavioral effects of exercise could be demonstrated in school children, we conducted Study II, partially with the perspective of exploring the arguments for applying exercise systematically in the educational system. In addition, since a team sport could be more motivating to school children compared to e.g. running, we investigated the effects of both hockey and running on motor memory. Seventy-seven pre-adolescent children (age: 10.48±0.75) were recruited to participate. The children were required to learn a motor task, and afterwards they were divided into three groups that performed 20 minutes of either intense running (RUN), intense indoor hockey (HOC) or rest (CON). We tested the children’s retention of the motor task one hour, 24 hours and seven days after acquisition. Both exercise groups performed better than CON seven days after learning, thereby replicating the results of Study I. There was no difference between HOC and RUN at any time points, thus implying that a team sport can lead to the same improvement of long-term motor memory as running. With Study III we explored the potential mediators of the observed behavioral effect of exercise on motor memory reported in Study I. Blood samples were drawn from subjects from PRE and CON groups at various time points before, during and after motor practice. The blood samples were analyzed for biomarkers suspected to be involved in facilitating the neuroplastic process that generates memory. Comparisons of the biomarkers with motor task performance scores suggested that factors such as brain-derived neurotrophic factor, norepinephrine and lactate could be important mediators of exercise to the nervous system. In summary, the studies demonstrated that a single bout of exercise performed before or after learning of a motor task can improve long-term retention of the task. Additionally, in children, performing a team sport can improve long-term retention as effectively as running. Our research suggests that norepinephrine, lactate and brain-derived neurotrophic factor might be involved in mediating the effect of exercise on motor memory. Overall, the results imply that exercise can be applied to facilitate long-term retention of motor memory.
Husserl Studies, 2014, Vol 31, Issue 2, p. 169-173
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Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen