BBoowwlliinngg GGrreeeenn SSttaattee UUnniivveerrssiittyy SScchhoollaarrWWoorrkkss@@BBGGSSUU Masters of Education in Human Movement, Human Movement, Sport, and Leisure Studies Sport, and Leisure Studies Graduate Projects 2017 RReeaaccttiioonn TTiimmee aass aa MMeeaassuurree ooff NNeeuurrooppllaassttiicciittyy AAfftteerr AAeerroobbiicc EExxeerrcciissee Ahmed Mostafa Follow this and additional works at: https://scholarworks.bgsu.edu/hmsls_mastersprojects HHooww ddooeess aacccceessss ttoo tthhiiss wwoorrkk bbeenneefifitt yyoouu?? LLeett uuss kknnooww!! RReeppoossiittoorryy CCiittaattiioonn Mostafa, Ahmed, "Reaction Time as a Measure of Neuroplasticity After Aerobic Exercise" (2017). Masters of Education in Human Movement, Sport, and Leisure Studies Graduate Projects. 52. https://scholarworks.bgsu.edu/hmsls_mastersprojects/52 This Article is brought to you for free and open access by the Human Movement, Sport, and Leisure Studies at ScholarWorks@BGSU. It has been accepted for inclusion in Masters of Education in Human Movement, Sport, and Leisure Studies Graduate Projects by an authorized administrator of ScholarWorks@BGSU. Reaction Time as a Measure of Neuroplasticity after Aerobic Exercise Ahmed Mostafa Research Project submitted in partial fulfilment of the requirements for Masters of Education (M.Ed.) Kinesiology Graduate Specialization School of Human Movement, Sport, and Leisure Studies Advisor: Stephen J. Langendorfer, Ph.D. Second Reader: Adam Fullenkamp, Ph.D. Reaction Time as a Measure of Neuroplasticity after Aerobic Exercise Abstract Until the 1960s it was commonly-assumed in neuropsychology that the adult human nervous system was hard-wired and had extremely limited capacity to change. Recently research has demonstrated that this earlier assumption was not accurate and that the adult human nervous system indeed is quite plastic and in a state of continuous change. Further, physical exercise has been demonstrated to promote positive effects on the adult human nervous system as a result of increased blood flow and modified neurotransmitters and neutrophins. These effects are hypothesized to improve the synaptic connectivity and promote neurogenesis, both of which are believed to play an important role in neural plasticity. The most commonly-used approaches to monitor neural plasticity have included the use of MRI images and measuring changes in levels of certain neurotransmitters in the brain. These approaches are expensive and not affordable to most physical activity researchers. The purpose of this study was to determine whether measures of simple and choice reaction time (SRT; CRT) could provide evidence of increased neural plasticity that has been documented to occur following moderate intensity aerobic exercise. I hypothesized that both SRT and CRT would decrease following moderate intensity aerobic exercise which might indicate improvement in neural plasticity compared to a control puzzle group. I assigned male and female volunteers (n=11), ages 18-30 years old, randomly to either an exercise group or a Sudoku puzzle-solving (control) group. I measured SRT using a computer software three times: pre-exercise/puzzle-solving (30 minutes), immediately post- exercise/puzzle-solving, and delayed (3 hours) post exercise/puzzle-solving. The between group independent variable was the intervention (either puzzle-solving or moderate aerobic exercise on a bicycle ergometer) and the within-subject (repeated measures) variable was the time of administration of pre-post-delayed-post reaction times (repeated measures) while the dependent Reaction Time as a Measure of Neuroplasticity after Aerobic Exercise measure was the simple reaction times (SRT) in milliseconds. The statistical analysis method used was a mixed factorial ANOVA. No significant differences in simple reaction time were discovered between the two groups or within the times of testing reaction time and no significant group by time interaction occurred. I concluded that one of four rationale could explain the lack of significant differences and have discussed the rationale in greater detail in the paper. I recommend the future replication of this study with a much larger sample size to increase the statistical power to detect differences as well as improving the consistency of the protocol and methods used in the study plus the addition of using choice reaction times or other valid measures of neural plasticity Introduction Until the 1960s it was a common textbook knowledge in neuropsychology that the adult nervous system is rather hard-wired and had probably a rather limited capacity to change (Hötting & Röder, 2013). Nowadays, many research papers have showed that, this knowledge was not right and human brain is in a state of continuous change. Plasticity is neither transient nor unique to developing organisms. However, as we develop the neural system stabilize once we achieve or reach optimal patterns of function. Stabilization decreases the system capacity to adapt but doesn’t eliminate it (Stiles, 2000) The term ‘neuroplasticity’ has multiple definitions. All these definitions do have some commonalties which fall into three categories: 1) process, 2) adaptation, and 3) organization. In terms of process, neuroplasticity describes the dynamic structural and behavioral changes that occur within the nervous system. Adaptation is defined as the system ability to adapt or recruit different resources in response to some external demand (Stiles, 2000). Organization: the process of plasticity is a systematic process, which is a product of interaction between the brain structures Reaction Time as a Measure of Neuroplasticity after Aerobic Exercise and the environment. According to Hötting & Röder (2013), “neuroplasticity refers to acquiring new skills after damage to the nervous system and/or as a result of sensory deprivation” (p.2244). Reaction time (RT) is the elapsed time between the presentation of a sensory stimulus and a subsequent behavioral response (Shelton & Kumar, 2010). Reaction time reflects or measures the level of neuromuscular coordination in response to visual or auditory stimuli. Simple reaction time (SRT) can be determined when an individual is asked to press (or release) a button as soon as a light or sound appears (Shelton et al., 2010). SRT indicates that the brain has processed and decoded the sensory stimuli and initiated the appropriate motor action in response to that sensory input. Thus, any increase in the RT may indicate an impairment or disruption in the cognitive processing or sensory information processing or in the initiation of the execution of motor behavior. Reaction time is the slowest among persons who have suffered cerebrovascular accidents and stroke followed by brain damage. Also, reaction time has an 86% accuracy in prediction of disease related mental decline. Thus, RT is frequently used as an index of central nervous system functioning and it implicates information processing time (i.e., sum of time for stimulus perception and preprogramming of the response prior to the execution of the desired action) (Ozyemisci- Taskiran, Gunendi, Bolukbasi, Beyazova, 2010) Exercise has many positive effects on the nervous system. According to Hötting & Rotter, (2013) “aerobic exercise improves blood flow, increases the secretion of neurotransmitters and neutrophins. Neutrophins are a group of proteins that regulate neural survival, development, function, synaptic function and synaptic plasticity” (Huang & Reichardt, 2001, p.1). These effects improve the synaptic connectivity and promotes neurogenesis, which are believed to play an important role in enhancing neural plasticity. Moreover, aerobic exercise is believed to directly Reaction Time as a Measure of Neuroplasticity after Aerobic Exercise enhance neural plasticity by “increasing brain driven neurotrophic factors (BDNF), Insulin like growth factor one (IGF-1,) stem cell proliferation, growth hormone (GH) and mitochondriogenesis. Exercise also may induce neurogenesis by decreasing HR, systolic and diastolic blood pressure, increasing cerebral artery flow velocity, and vascular growth” (Archer, Svensson, & Alricsson, 2012, p. 295). BDNF is a protein that plays an important role in in growth, cell differentiation, neural development, increasing resistance to damage and improving the survival of neurons. Also, BDNF is used as a measure or an indicator of exercise effects on injured neurons (Jeon & Ha, 2015). According to Jeon & Ha (2015) “insulin-like growth factor 1 (IGF- 1), one of the factors involved in BDNF expression, is known to mediate regulation of genes involved in BDNF-related neurogenesis, and it is involved in the growth and differentiation of neuron units of the brain” (p.737). In a study where the functional brain changes after trauma were studied, the researchers identified 10 principles of experience-dependent neuroplasticity: “Use it or lose it, use it and improve it, specificity, repetition matters, intensity matters, age matters, salience matters, time matters, inference and transference” (Kleim & Jones,2008, p.227). Physical exercise can partially reverse some of the brain damage after trauma. This exercise effect could be attributed to anti- apoptosis, anti-inflammatory, decreased depression, anxiety and stress effects of exercise. According to Archer et al (2015), exercise may promote neural plasticity by “increasing growth hormone, stem cell proliferation, mitochondriogenesis, and brain-derived neurotropic factors. Moreover, it promotes angiogenesis by increasing cerebral artery flow velocity and vascular growth” (p.295). Neuroplasticity also may result in a maladaptive behavior consequences. The exercise effect of reorganization on the central nervous system could result in an undesirable form of Reaction Time as a Measure of Neuroplasticity after Aerobic Exercise reorganization. For example, reorganization of somatosensory and motor areas has been reported to be accompanied with focal dystonia (Hötting & Rotter 2013). So, the mechanism that causes improvement in performance could cause maladaptive effects. Therefore, the course of neuroplasticity should be monitored closely and carefully. Monitoring neuroplasticity on daily bases is an unachievable task, because the most commonly used methods to monitor plasticity is MRI which is very expensive and non-handy device. Based on this recent literature findings related to exercise and neuroplasticity, I hypothesized that I should expect to observe a decrease in reaction times following moderate aerobic exercise either immediately or during the period up to 3 hours after exercise compared to the pre-exercise reaction time as well as compared to a non-exercise control group. Method Participants Participants in this study included 11 Bowling Green State University students. Participants included 11 males between the ages of 18 and 28 years with an average age of 20.91 years and standard deviation of 2.43 years (see Table 1). All participants in this study were volunteers who completed informed consent forms that contained information about the purpose of the study, procedures, benefits and risks of participation, voluntary participation, contact information of the researchers, and the institutional review board (IRB). Participants were informed that they could withdraw without penalty and in order to assure no pre-existing conditions, a pre-participation health screening questionnaire assessed the self-reported health status of the participants. The questionnaire included questions about history of any heart diseases, operations, asthma, diabetes, smoking, medications, blood pressure and Reaction Time as a Measure of Neuroplasticity after Aerobic Exercise musculoskeletal problems that would limit physical activity. The existence of any condition would have eliminated the participant from the physical exercise group in the study. Table 1 Ages of participants in each group. Exercise Sudoku Sample Mean 21.5 20.2 20.91 S.D 3.39 0.84 2.43 Number 6 5 11 The table shows the difference in average age of participants in each group, standard deviation and the average age of both groups combined together. *Note SD= Standard Deviation. Measures Reaction Time Measurement v.1.0 software by Cognaxon was used to measure the simple reaction time (SRT), the movement time (MT), and total response time (TRT). SRT, MT and TRT were all used in the analysis of the results of this study. Initially, choice reaction time (CRT) was intended to be measured, but problems with the software prohibited its use. Procedures As participants arrived at the research site, they were asked to have a seat and read the informed consent. After the investigator answered any questions, they signed the informed consent and then completed the pre-participation screening questionnaire which they also signed. Participants were assigned simple code numbers using the order in which they were tested. Participants with odd numbers were assigned to the aerobic exercise group and participants with even numbers were assigned to the puzzle-solving group. The researcher asked the participants if they have any questions or concerns about participation in the study. Reaction Time as a Measure of Neuroplasticity after Aerobic Exercise When the first participant arrived, he was assigned to the aerobic exercise group after he completed the informed consent, the health survey, and the investigator answered any questions. A Cardio Sport Start2 heart rate monitor was used to measure each exercise participant`s resting heart rate (RHR). RHR was measured three times while seated and the average was used as the baseline resting heart rate. The reaction time software was installed on a Dell Inspiron 5520 laptop and a Logitech M 185 wireless computer mouse was used to conduct the SRT trials. The participant was allowed to do as many practice SRT trials as he needed to get accustomed to the software and mouse; then each participant completed 25 trials of SRT. The RT software displayed the following instructions at the start of every trial: “Press left mouse button. Keep left mouse button pressed until a white circle shows up. Then release the left mouse button and press right mouse button as quickly as you can.” Participants took approximately 3 minutes to finish the 25 trials. After finishing the trials the results were copied to an Excel spreadsheet and the participant then began either the exercise or puzzle-solving intervention. Each member of the exercise group pedaled on the Monarch cycle ergometer (MONARK Ergo medic Model 828 E) after the seat was adjusted so the participant`s knees are not hyperextended. Exercise participants were asked to maintain a target exercise heart rate of approximately 50% of his heart rate reserve (HRR) as calculated by the standard formula. Formula 1 Calculation of heart rate reserve (HRR) 1) Max HR = 220- age, 2) Resting HR reserve = Max HR- Resting HR, 3) Resting HR Reserve X 0.50 (percentage of Max HR) and 4) Target HR= (product of the third formula) + resting HR). Immediately Upon completing 30 minutes of cycling exercise at the 50% heart rate reserve, a post- test SRT test of another 25 trials was conducted. The participant was then asked to return Reaction Time as a Measure of Neuroplasticity after Aerobic Exercise approximately 150-180 minutes later at which time he completed the second delayed post-test SRT test, again for 25 trials. When the second participant arrived, he was assigned to the puzzle-solving group after he completed the informed consent, the health survey, and the investigator had answered any questions. Then, participant two was asked to have a seat to do the pre-SRT time test after which he was asked to start working on a Sudoku puzzle for 30 minutes. Standard Sudoku puzzles were copied from https://worksheets.theteacherscorner.net/make-your-own/sudoku/. Upon working on the Sudoku puzzle for 30 minutes, the second participant was asked to do the post-puzzle- solving SRT test. Upon completing the 25 SRT trials and having the SRT values entered into the Excel spreadsheet, the participant was asked to return again in 150-180 minutes for the third, delayed SRT measurement. Subsequent participants (i.e., #3 through #11) were tested using protocols identical to the first two as described above. Statistical analysis All statistical analyses were calculated or conducted using SPSS version 22 software. Box’s test of equality of covariance matrices was used to check the assumption of homogeneity of covariance across the groups using p < .05 as a criterion. Levene’s test of Equality of Error Variances was used to determine whether variances of each variable were equal across the groups. A two-factor, mixed effects factorial Analysis of Variance (ANOVA) (2 (groups) x 3 (time periods)) with repeated measures on the second factor was used to analyze the main effects between group and time factors as well as any groups by time interaction for mean SRT (see Table 4).