The effects of aerobic fitness and athletic participation on executive control functioning and motor response selection

The present study was conducted to analyze the effects of overall levels of physical fitness on executive control functioning, measured by accuracy and reaction time on an Erikson flankers task as well as EEG measures such as the P300. Lateralized readiness potentials were also studied to see if training in motor reactivity for athletic teams or physical fitness played any role in their onset or strength. Participants were found to be more accurate on trials where the target stimulus and flanking stimulus were congruent. These trials also elicited faster response times, shorter P300 latencies and shorter stimulus-locked LRP latencies. Athletic participation did not have a main effect on any measures of interest in this study, but participants’ aerobic fitness levels (measured by their VO2 max) were found to be correlated with response times on congruent and incongruent trials. Greater interaction effects between electrode site and task congruency also emerged in lower-fit control subjects, but were not apparent in athletic populations. Although the aerobic fitness levels were shown to be statistically higher for athletes as opposed to non-athletes in this study, the overall homogeneity of this sample based on age and mental capacity may have dampened effects. The Effects of Aerobic Exercise 3 The Effects of Aerobic Fitness and Athletic Participation on Executive Control Functioning and Motor Response Selection Throughout history, philosophers and scientists have attempted to understand the connection between the mind and the body. In recent times, science has taken a more holistic approach by studying the interaction as opposed to the dichotomy of these two entities. Although it has been clear for quite some time that the brain, in particular the motor cortices, are able to control muscle movements and bodily functions, contemporary research has chosen to focus its efforts on trying to understand the impact that the physical body may have on the mind. This study intends to further define the link between the body and the mind by investigating the effects of long-term physical fitness and athletic participation on the human cognitive processes that are involved in stimulus perception and response selection. This paper will analyze past research that has been useful in outlining the specific aspects of fitness and cognition that are strongly linked and the ways in which modern technology (e.g. electroencephalography) have been used to further tease apart the benefits that physical fitness can impart on the mind. This study hopes to add to this strain of research as well as explore new connections between these two entities that have been neglected in past research. Exercise and the Mind Besides physically conditioning the body, the act of exercising has been shown to enhance numerous aspects of mental functioning, such as mood, self-esteem, and general psychological well being (Plante & Rodin, 1990). People who have participated in an aerobic exercise class for over six months have been shown to report lower levels of overall stress and more positive affect in their everyday life than people who did not participate in aerobic activities for extended periods of time (Dua & Hargreaves, 1992). There has also been some The Effects of Aerobic Exercise 4 research showing that exercise programs can benefit patients suffering from clinical depression (Khatri, Blumenthal, Babyak, Craighead, Herman, Baldewicz, Madden, Doraiswamy, Waugh & Krishnan, 2001). One account offered to explain these psychological benefits is that exercise enhances the levels of certain neurotransmitters, such as serotonin, norepinephrine and dopamine, which play a key role in mood regulation. In addition to these dispositional benefits, Potter and Keeling (2005) suggest that alterations in the level of these neurotransmitters may also play a key role in various aspects of cognitive functioning, such as enhancement of both working and long-term memory. Exercise has also been shown to produce similar improvements in the cognitive functioning of animals by impacting the development and maintenance of the hippocampal region of the brain, which is responsible for visual/spatial memory (van Praag, Kempermann & Gage, 1999). This results in improved speeds at which these animals can perform new spatial and behavioral learning tasks (Churchill, Galvez, Colcombe, Swain, Kramer & Greenough, 2002). Hippocampal cell survival, cell proliferation and neurogenesis in adult mice have been found to be aided by unrestricted access to an exercise wheel, suggesting that such activity could have analogous effects in humans (van Praag, Kempermann & Gage, 1999). Although the relatively highest level of cognitive processing for rodent subjects occurs in the hippocampal region, it is the frontal cortex, a structure whose cognitive abilities are not adequately represented in less complex animal subjects, that is responsible for the highest level of cognitive functioning in the human brains. In this way, parallels can be drawn between the hippocampal region of the rodent brain and the frontal lobes of the human brain. This may explain why there has not been overwhelming evidence showing exercise to be effective in enhancing performance on spatial memory tasks in human subjects, a cognitive ability that is The Effects of Aerobic Exercise 5 primarily mediated by the hippocampal region of the brain (Blumenthal and Madden, 1988; Tomporowski & Ellis, 1986). The Frontal Lobes and Executive Control Functioning If it is true that exercise, as it has been hypothesized, has its largest effects on the most complex cognitive functions, then one should investigate the cognitive tasks that are performed by the human brain’s frontal cortex. One of the most prominent areas of cognition localized in the frontal lobes of the human brain is executive control functioning (West, 1996). Executive control functions are controlled tasks that do not become automatic over time and require constant mediation by the central executor, such as coordination, inhibition, scheduling, planning and working memory (Colcombe & Kramer, 2003). These executive control functions require considerable amounts of attention, which is the general process of selective perception of sensory information. What a person directs their attention towards may be influenced by what the person perceives as being important. Cues may also help the person direct their attention to what they consider to be important. Selective attention tasks are often used to study an individual’s executive functioning capacity by measuring that person’s ability to attend to various sensory information. Tasks of this nature ask the participant to direct their attention to one feature of the stimulus and enact a motor response upon the presentation of this particular feature. The studies that have found the strongest impact of physical fitness have used reaction time tasks to measure effortful cognitive processes that require a considerable amount of attention (Chodzko-Zajko, 1991). Aerobic exercise has been shown to be the most beneficial type of physical activity for the enhancement of executive control functioning (Churchill et al., 2002; Kramer & Willis, 2002). One of the reasons that aerobic as opposed to anaerobic activity in particular is thought to The Effects of Aerobic Exercise 6 better enhance executive control functioning may be through its ability to improve neurological functioning by increasing blood circulation within the brain (McAuley, Kramer & Colcombe, 2004). When performed regularly, aerobic exercise can lead to increases in aerobic fitness and one’s capacity for oxygen intake, which, in turn, provide the brain with a more ample blood supply. When more blood is allowed to flow through the brain, more nutrients, such as glucose and oxygen, are able to be delivered to important structures that influence an individual’s cognitive functioning. Kramer, Hahn, McAuley, Cohen, Banish, Harrison, Chason, Boileau, Bardell, Colcombe, and Vakil (2001) argue that frequent aerobic exercise plays a large role in the maintenance of cerebrovascular activity and cardiorespiratory functioning, which can in turn help to sustain cognitive aptitude as humans enter into old age. Aging, Fitness and Cognitive Functioning Neurological and cognitive declines related to perceptual, motor and executive control functioning are often associated with aging (Kramer & Willis, 2002). Studies examining the impact of exercise and physical fitness on elderly populations have the ability to provide much insight into the possible physical bases influencing the supposedly natural declines in cognitive functioning. The results of some of these studies have cast a doubt upon the belief that these declines are in fact natural, suggesting that their origins may rest in common drops in physical activity levels during the human lifespan. Through the use of functional magnetic resonance imaging (fMRI), McAuley et al. (2004) found that higher fit older individuals exhibited less gray matter loss and less loss of white matter tracts than their less fit counterparts. This study also examined the fMRI data taken before and after subjects’ randomly selected participation in either an aerobic training program or non-aerobic control condition. Results suggested that participants in the aerobic training condition benefited from increased cardiovascular fitness levels, showing The Effects of Aerobic Exercise 7 less behavioral interference during a flankers task. The fMRI data from both studies suggest that aerobic fitness significantly moderates the trajectory of age related tissue loss (McAuley et al., 2004). However, it is often difficult to assign causality when examining the relationship between exercise and cognition. It may be that the individuals’ cognitive aptitude influences their decisions to engage in physical activity, rather than the opposite causal path. Hence, longitudina