INTRODUCTION National statistics indicate that Americans engage in a low rate of regular physical activity. Approximately 25% of adults report no leisure-time physical activity (United States Department of Health and Human Services [USDHHS], 1991). Furthermore, the prevalence of sedentary behavior increases with advancing age. A report from 1996 fount that 52.8% of adults do not engage in exercise or do not exercise regularly (Alaska Department of Health and Social Services [Alaska DHHS], 1998). Results of the MacArthur Foundation Study (Kahn & Rowe, 1998), the New England Centenarian Study (Perls & Silver, 1999), Christensen and MacKinnon (1993), and Emery, Huppert, and Schein (1995) confirm the importance of exercise to maintain and improve physical and cognitive functioning. Memory is defined as “the mental processes of retaining information for later use and retrieving such information” (Birren, Sloane, & Cohen, 1992, pg. 308). Memory is classified into two categories: short-term, also known as episodic or working memory, and long-term. Short-term memory can last from a few seconds to one hour. Long term memory can last for a lifetime (Lezak, 1995). Decreased cognitive functioning, such as memory loss, is most frequently associated with aging, diseases, and injury. Pender (1996) emphasizes the benefits of physical exercise for all body systems and the nurses’ role to provide motivation and education to their clients. Walking is a great form of exercise available to people of all ages without the need of special equipment. Walking is believed to be good for an individual’s health, even in relatively small amounts. The data suggests that there is a potential importance of physical exercise, such as walking, in maintaining or enhancing cognitive performance in older adults. These results are consistent with the studies done by Dustman et al. (1984) and by Molloy et al. (1988). An association between physical fitness and cognitive performance has been identified for certain cognitive tasks. However, there is little consensus with respect to the specific aspects of cognitive processing that are most likely affected by physical fitness. Elsayed, Ismail, and Young (1980) proposed three reasons why exercise improved fitness and also enhanced cognitive functioning. They proposed that increased transportation of oxygen and glucose to the brain, as well as increased self-esteem and decreased psychological distress, would result in improved performance on complex psychological tasks. Rogers, Meyer, and Mortel (1990) conducted a study with 80 elderly volunteers. They measured cerebral blood flow and cognitive performance using the radioactive Xe inhalation method and a standardized cognitive screening. As a result of this study, Rogers et al. proposed that regular participation in physical activity could minimize cognitive decline by sustaining optimal “cerebral perfusion”. Capaldi, Hawkins, and Kramer (1992) agreed with Rogers et al. that oxygen and blood to the brain affect mental function. They based this conclusion on the fact that cardiovascular conditioning through physical exercise increases aerobic capacity and cardiac output by increased stroke volume and oxygen extraction. As a result, cardiovascular conditioning may reduce or reverse age related declines in mental function attributed to cerebrovascular insufficiency. Molley et al. (1988) found that short-term improvements in cognitive functioning of older adults with memory complaints immediately following a single 45 minute span of exercise. A significant improvement in logical memory and in the Mini-Mental State Test scores was found after exercise compared with the control group. The increase in logical memory represented an improvement in short-term memory and confirmed the findings of Diesfeldt and Diesfeldt-Groenendijik (1977), who reported an improvement in recent memory following light exercise in a debilitated psychogeriatic group. The positive impact of exercise on physical well-being has been well documented. The relationship correlates with the extent to which the cardiovascular system is stressed and is quantifiable (Brooks & Fahey, 1984). Past research has reported effects of exercise-induced physical arousal on cognitive processes. The results have been inconclusive and lack a quantified base (Tomporowski & Ellis, 1986). The idea that exercise improves mental attitude and performance has been the basis for many corporations establishing fitness programs. Therapeutic effects have been shown for hyperactive children (Craft, 1983). Exercise has been suggested as a tool for intervention in the natural degeneration of mental processes with age (Del Rey, 1982 & Hughes, 1984). It is, therefore, important to establish clearly and quantitatively the effects of exercise on mental processing. The purpose of this study was to investigate the effects of exercise on short-term memory in college students. My hypothesis was that exercise would improve short-term memory in college-age adults. This study examined the effect of activity on subjects’ performance on a short-term memory test.
METHOD This was an experimental study to investigate if exercise has an improved effect on short term memory. A Digit Span Memory Test was conducted pre and post exercise to determine if exercise improved short-term memory scores. My hypothesis was that exercise would improve short-term memory. PARTICIPANTS
The sample for this study was recruited by convenience. All participants were students of Milligan College during academic spring semester 2007. Most of the participants in the study were collegiate athletes which the remainder were non-athletes, but were physically active. As a way to recruit more participants, some faculty members offered extra credit for participation in this study. All of the participants read and spoke English. All of the study participants volunteered. The sample consisted of 12 participants from Milligan College. MATERIALS
Short-Term Memory was measured by Digit Span Memory Test. This is a neurological test to measure memory in adults. This test required the subject to write down a series of numbers increasing one digit at a time, up to nine digits, then repeat a series of numbers increasing one at a time up to seven digits and recall backwards. A person of average intelligence can accurately repeat five to seven digits. The inability to repeat more than five digits indicates defective attention and short-term memory. The Digit Span Test was modified from original test. Modification was necessary because only a clinical psychologist can administer this test. Single digit numbers between three and nine were spoken by researcher at the rate of one digit a second and were written down, recalling the numbers in forward order, on a provided answer sheet. After the first series of numbers another series of numbers between two and seven were spoken by researcher at the same rate of one digit a second and were written down, recalling the numbers in backward order, on provided answer sheet. The score for the study participant was one point for the correct number in the correct number place in series. PROCEDURE
The setting for data collection was on Milligan College campus inside Steve Lacy Fieldhouse in classroom 1 and basketball court. The Digit Span Memory Test was conducted in a quite classroom, while the exercise was on the basketball court/gym floor. The researcher gave an explanation of the study, both in writing and verbally, when the participant volunteered. All participants were asked if they had any questions before the process began. Written consent was obtained from each participant prior to beginning of study. The Digit Span Answer Sheet was give to all participants. The participants were informed that short-term memory would be assessed before and after physical exercise. The Digit Span Test was administered in the following format: “I am going to say a series of numbers beginning a sequence of three numbers then increase by one number until the series has a total of nine numbers. Once that set of numbers is completed there is another set of numbers. This set starts with two numbers and increases to seven numbers, but this time you must recall the number series backwards. The blanks are provided on answer sheet to write the number. Listen carefully and when I am finished with a set of numbers, write down the number series from memory. I can not repeat the series of numbers so you must pay careful attention each time.” The numbers series were spoken in a normal tone of voice at the rate of one digit per second. These sequences increased until both sets of numbers reached max number of nine and seven. After the first Digit Span Test was administered the participants left the classroom and proceeded to the basketball court. The participants started walking the perimeter of the basketball court (94’ long X 50’ wide) for fifteen minutes at a moderate pace of approximately three miles per hour. Time was kept by the researcher using a stopwatch. Once time reached fifteen minutes the participants went back into the classroom for the post-exercise Digit Span Test. The post-exercise Digit Span test was conducted identically to the pre-exercise test. Once the post-exercise test was completed the participants received confirmation letter of study to give to professor for extra credit. Water and crackers were provided at the end of the test. PROTECTION/CONFIDENTIALITY
The consent form and question & answer session explained the purpose of the study, that participation in the study was voluntary, withdrawal from the study could occur at any time, that the study had no known risks or benefits to the participant, the responses to memory test would not be released, and who to contact for information and questions. The names of the participants did not appear on any data result forms used in this study. SCORING INTERUPPTION
One point was awarded for the correct number in the correct place in number series. The total score that could be achieved from the first part of the digit span was 84 points. And a total score of 52 for the second part of test. Total points possible for both sections were 136. However, there was a cell phone interruption after the numbers had been called during the first test on question number 9 on the second section of test. The scoring for this question ranged from 6 (perfect score) to 0. This question was thrown out for both pre and post exercise memory test. This changed the total possible points for the second part to 46 (total points for question: 6 subtracted from total possible points in second section: 52). DATA ANALYSIS
The purpose of this study was to investigate if exercise improved short-term memory, as measured by the Digit Span Test. The total possible score for the forward recall number series was 77 and for the backward recall number series was 46. This made a total possible score of 123. Each participants test was scored and compared to their test pre-exercise
RESULTS The mean for test trial 1 was 105.58 and the mean for trial 2 was 108.75. A dependent t-test was run to determine significance level of test results. The results indicated a significant difference between the trials, t(11) = 1.83, p< .05.
DISCUSSION Based on this study, exercise does improve short-term memory in college-age adults. Our hypothesis of exercise improving short-term memory was supported. Prior research has demonstrated the relationship between increased cognitive function with exercise for the older adult, but relatively few studies have demonstrated this relationship in the younger adult. Evidence is needed demonstrating the nervous system effects in the brain produced by exercise and how these changes influence the learning process. Studies on the effects of endurance exercise on short-term memory have been equivocal. Controlled quality research is necessary to refine the observations in this area. Consequently, the effect of an acute bout of aerobic exercise on short-term memory was studied in this experiment. Short-term memory was defined for this study as the memory system which old the memories which are present and active in the brain at a given moment (Schneider & Tarshis, 1986, p.518) as measured by the digit span test scores.
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