Exercise Psychology: Understanding the Mental Health Benefits of Physical Activity and the Public Health Challenges of Inactivity
Abstract and Keywords
Regular physical activity is important for optimal physical and mental health. Furthermore, physical inactivity has been identified as a leading cause of death (U.S. Department of Health and Human Services, 1996). However, the Centers for Disease Control and Prevention (Barnes, 2007) have reported that fewer than 50% of Americans participate in regular physical activity. This information highlights the public health challenge of increasing participation in physical activity to enhance physical health and to buoy the psychological benefits associated with physical activity.This chapter presents a brief synopsis of the evidence that compels the study of exercise psychology. In addition, as a basis for assimilating the content of subsequent chapters, this chapter includes explanations for terms often used in exercise psychology, important methodological and conceptual clarifications, and a preface to the topics addressed throughout this text.
Lack of activity destroys the good condition of every human being, while movement and methodical physical exercise save it and preserve it.
Throughout most of history the physical requirements of survival have been a defining element of human existence. However, within the last 150 years, industrial and technological advancements have made survival no longer intricately dependent on physical demands. With little need for physical activity to perform important work for society, ease of transportation, and almost effortless access to information, most of the population must make a conscious effort to incorporate physical activity into their lifestyles. The challenge to self-regulate exercise behavior has had unexpected, negative health consequences. This challenge, along with the documented psychological benefits associated with participating in physical activity, is central to the arguments supporting the study of exercise psychology.
This chapter provides a brief presentation of the evidence that compels the study of exercise psychology. In addition, it presents explanations for terms that are used in the field of exercise psychology. Together these will serve to define the broad scope of this interdisciplinary field. The cross-fertilization of knowledge has had a tremendously positive effect on the development of exercise psychology. In addition, this chapter clarifies important methodological and conceptual issues that will provide a (p. 4) platform from which to assimilate the content presented in subsequent chapters. In particular, a number of issues relevant to the combined investigation of physical activity and behavior are included—for example, the challenge of assessing physical activity, the relationship of physical health outcomes to mental health outcomes within the context of standard exercise prescription guidelines for physical health outcomes, and, although minimal and far outweighed by the benefits, the health risks associated with exercise. This chapter also includes a preface to the topics addressed in this text.
In 1996 the Surgeon General's Report identified physical inactivity as a leading cause of death. Since the publication of that report, physical inactivity has contributed to the deaths of approximately 200,000 Americans per year (Danaei et al., 2009). Even with the common understanding of the importance of physical activity to health (Bouchard, Blair, & Haskell, 2007), the Centers for Disease Control and Prevention has reported that fewer than 50% of Americans participate in regular physical activity (Barnes, 2007). Furthermore, evidence supports the benefits of physical activity to mental health, including improvements in depression, anxiety, self-concept, quality of life, and cognitive function (see Faulkner & Taylor, 2005). Promoting physical activity has clear relevance to improving physical and mental health. This text provides in-depth analyses of the literature that examines the behavioral, affective, cognitive, and psychobiological antecedents and consequences of physical activity, with a focus on the adoption and maintenance of physical activity and its effects on psychological well-being.
Regular physical activity can help in controlling weight; reducing the risk of cardiovascular disease, type 2 diabetes, metabolic syndrome, and some cancers; improving bone strength; and improving the ability to do daily activities and preventing falls in older adults (USDHHS, 1996). The financial cost of the physical health consequences of inactivity is approximately $250 billion (Chenoweth & Leutzinger, 2006). In addition, the benefits of physical activity include alleviating depression, decreasing anxiety, enhancing self-concept and cognitive function, attenuating the stress response, and improving general mood states (Faulkner & Taylor, 2005). These mental health benefits are important when one considers that at least one in five people in the United States has a diagnosed mental disorder, and the estimated direct cost of mental health services is now more than $99 billion (U.S. Department of Health and Human Service, 1999). These physical and mental health benefits, along with the potential reduction of the dramatic financial costs of poor health, provide great impetus for the promotion of physical activity as a public health goal.
An understanding of the mental health benefits of exercise has developed from an appreciation of the value of interdisciplinary investigation into the psychobiological nature of the physical activity experience. The study of exercise psychology provides an excellent model for examining the link between the mind-brain and the body. This age-old concept is highlighted in the quote that begins this chapter. An even more compelling consideration is that physical fitness is necessary for optimal physical and mental health, including cognitive function (Kramer, Erickson, & Colcombe, 2006), and “to make normal life more fulfilling” (Seligman & Csikszentmihalyi, 2000). This is a central proposition of the conceptualization of positive psychology by Seligman and Csikszentmihalyi.
The terms physical activity and exercise are often used interchangeably; however, there are subtle differences. Physical activity is defined as “any bodily movement produced by skeletal muscles that results in energy expenditure” (Caspersen, Powell, and Christenson, 1985). In the literature examples of physical activity include activities of daily living, participation in sports, exercise, and leisure-time activity. However, the literature goes further in defining exercise as a form of structured physical activity with the specific objective of improving or maintaining physical fitness or health. The psychological study of emotions, thoughts, and behaviors of physical activity versus exercise also maintains this subtle distinction between structured physical activity and physical activity encompassing all types of movement. It is important to appreciate that, as Gill (2009) has noted, “Physical activity is the key to positive health and quality of life, and, thus, lifetime physical activity is the base for healthy lives” (p. 691). However, the primary focus of this text is the development of empirical evidence in support of physical activity programs that promote health. A major challenge in developing such knowledge is assessing physical activity as a stimulus for improvements in health. The necessity or desire to efficiently and effectively quantify, prescribe, and promote physical activity to increase the likelihood of a positive health outcome is the rationale for the use of “exercise psychology” in the title of this text. Nonetheless, throughout this text and in parallel (p. 5) with the literature, “physical activity” and “exercise” are often used interchangeably.
The historical development of exercise psychology has been fueled by a broad range of disciplines and interdisciplinary approaches. In 1986, the research journal Journal of Sport Psychology changed its name to the Journal of Sport and Exercise Psychology to include this promising area of investigation. Since then a number of new journals addressing exercise psychology have included “exercise” or “physical activity” in their titles, including Psychology of Sport and Exercise, International Journal of Sport and Exercise Psychology, Mental Health and Physical Activity, and International Journal of Behavioral Nutrition and Physical Activity. Today inquiries into the behavioral aspects of exercise and physical activity originate from health psychology, rehabilitation psychology, positive psychology, psychobiology, neuroscience, behavioral epidemiology, behavioral medicine, and exercise science. Furthermore, scientific journals from these disciplines and subdisciplines frequently publish articles on research that uses physical activity as an independent variable. The plethora of work parallels the demand for knowledge in this area. Comprehensive historical accounts of the field of exercise psychology have been presented by Rejeski and Thompson (1993) and Buckworth and Dishman (2002).
The exercise psychology literature most often examines exercise or physical activity as an independent variable. A clear understanding of the benefits of this stimulus (physical activity or exercise) requires an operational definition. When interpreting the exercise literature one must recognize that the exercise stimulus can be either acute—a single relatively short bout of exercise—or chronic—exercise that is carried out repeatedly over time, usually for a number of weeks. To further describe the physical challenge of an exercise program the duration of the activity, intensity of the activity, the type of activity, and the frequency (per week) must be identified. In 2007 the American College of Sports Medicine (ACSM) and the American Heart Association (AHA) provided updates to their physical activity guidelines based on the most relevant science that links physical activity to enhanced health and quality of life (Haskell et al., 2007). ACSM/AHA guidelines recommend a minimum of 30 minutes of moderate-intensity aerobic physical activity five days a week. Alternatively, individuals can accumulate 30 minutes over the course of a day with shorter bouts that total 30 minutes. These guidelines are considered minimal recommended amounts. Finally, the exercise stimulus does not have to be aerobic. It can also be anaerobic, which includes resistance exercise (weight training), and it can be a combination of activities. These types of exercise have received little attention in the exercise psychology literature. The parameters of the physical stimulus (exercise) to be studied must be clearly defined so that one is able to compare “apples to apples” or be able to identify differences in the stimulus to compare “apples to oranges.”
Key Methodological and Conceptual Clarifications
While the ACSM/AHA guidelines address the activity requirements for physical health, these guidelines do not address the exercise stimulus necessary for mental health benefits. Furthermore, the mechanisms that explain the physiological adaptations to exercise that impact physical health have received much attention, whereas the psychobiological mechanisms that explain the mental health benefits have only recently been investigated. It is intriguing to consider the exercise stimuli that are necessary to elicit positive mental health outcomes, and which mechanisms explain these adaptations. Interestingly, while the mental health benefits of aerobic exercise have begun to be explored, the psychological responses and mental health benefits of anaerobic exercise, resistance exercise (weight lifting), and combinations of activities have received little attention in the literature. Thus, although aerobic physical activity is associated with significant mental health benefits, the challenge still exists to define a specific exercise prescription for a specific mental health benefit. It may be that the mental health outcomes are not contingent on changes in the physiological parameters that have supported the ACSM/AHA guidelines.
In addition, the exercise psychology literature has understandably struggled in its attempt to measure physical activity as a perception and as an objective physical stimulus. Valid and reliable assessment of physical activity is important in the investigation of the direct relationship between physical activity and mental health; in the study of physical activity patterns, determinants, and barriers in different populations; and in evaluating the effectiveness of physical activity interventions (Pols, Peeters, Kemper, & Grobbee, 1998; Washburn, Heath, & Jackson, 2000). Furthermore, addressing the dose–response relationship with psychological outcomes necessitates the accurate measurement of physical activity.
(p. 6) The literature has included subjective (self-report questionnaires, diaries) and objective measures (heart rate monitors, pedometers, accelerometers, doubly labeled water), with the inherent advantages and disadvantages of both. More specifically, self-report measures are relatively inexpensive, are easy to administer, and can be used with large samples. Conversely, objective measures, although they are not subject to recall error and are generally unobtrusive, can often fail to assess specific types of activities (water sports, arm exercise, walking or running on an incline) and can be very expensive. In addition, the use of a specific technique may be limited by the ability of the participant to follow instructions. Thus the age and any special needs or characteristics of the participants must be considered. Welk, Blair, Wood, Jones, and Thompson (2000) have proposed that accelerometers, which measure movement based on acceleration and deceleration of the body, provide the most reliable and valid measure of physical activity for research purposes. However, an objective measure of physical activity does not preclude the importance of assessing individuals’ perceptions of the amount of their physical activity participation. Depending on the research question, the perception of activity may be more critical to the research question or outcome of interest than the actual or objective assessment of physical activity. Tudor-Locke and Meyers (2001) in their review have suggested that the use of multiple measures will likely increase the accuracy of the assessment. Our understanding of exercise psychology will continue to progress in parallel with the improvements in the tools for assessing physical activity.
An aspect of exercise that must be considered prior to embarking on an examination of its benefits is the potential health risks associated with physical activity participation. While the benefits clearly outweigh the risks (USDHHS, 1996), understanding the risks provides insight that can be used to minimize the possibility of an adverse event or response to physical activity. The two most discussed risks are myocardial infarction and musculoskeletal injuries. Individuals with underlying heart disease are at increased risk of a cardiac event during physical activity because of the additional stress it places on the heart and circulatory system. However, this stress also serves as a stimulus for improved cardiovascular function. Ultimately, physical activity reduces the risk of cardiovascular disease by at least half (Kohl, Powell, Gordon, Blair, & Paffenbager, 1992). Cardiac patients can experience considerable improvements, but must take appropriate clinical precautions when participating in physical activity (ACSM, 2010).
Most physical activity–related injuries can be categorized as overuse injuries. These musculoskeletal injuries are associated with the frequency, intensity, and duration of exercise (Pate & Macera, 1994). Thus the risk of these injuries can be minimized by a reduction in the frequency, intensity, or the duration of the activity. The recommendations for health-related physical activity by the ACSM (2010) are moderate enough to limit the incidence of overuse injuries for most people (Pate et al., 1995). At very high levels of activity health problems can include dehydration, hyperthermia and hypothermia from exercise in extreme environmental conditions, amenorrhea, anemia, and suppression of immune function. In general, these conditions, when monitored, can be improved with an appropriate decrease in the level of physical exertion or limitation of physical activity participation.
Several mental health problems related to exercise have received some attention in the literature. Exercise dependence—a combination of high levels of physical activity participation and a strong perceived need to exercise despite all obstacles (Davis, Brewer, & Ratusny, 1993)—can interfere with social and work activities and lead to or exacerbate injuries. In addition, in habitual exercisers withdrawal from exercise can elicit depressive symptoms, anxiety, and symptoms of emotional distress (Mondin et al., 1996). Current understanding of the extent and severity of exercise dependency across the population is very limited. Interestingly, Coen and Ogles (1993) have found that participants who rated high on exercise dependency had less psychopathology and less body image distortion than individuals with anorexia nervosa. This distinction suggests that although exercise dependency and anorexia share some similar characteristics, the severity of the potential medical and psychological consequences is much greater for anorexic individuals. Finally, Morgan, Brown, Raglin, O'Connor, and Ellickson (1987) have reported that athletes, as a result of overtraining (when the volume and intensity of exercise exceeds an individual's recovery capacity and performance is compromised), can experience symptoms of chronic fatigue, muscle soreness, insomnia, and disturbed mood. Although substantial evidence supports the detrimental psychological (p. 7) consequences of excessive physical activity, this evidence must be considered in light of the plethora of data demonstrating the beneficial physical and mental health effects of appropriate levels of exercise and the fact that fewer than 15% of U.S. adults, a relatively small portion of the population, regularly participate in vigorous exercise (USDHHS, 1996). Thus the challenge of increasing physical activity is pertinent to enhancing physical and mental health and addressing the tremendous cost to society of inactivity.
The contents of this authoritative and comprehensive text present the breadth and depth of empirical contributions using state-of-the-science theories and approaches in exercise psychology. The authors are leading investigators who have made significant scientific contributions to the literature examining the behavioral aspects of physical activity, and each chapter presents a summary of scientific advances in the topic area as a foundation for future investigation. To provide a context for interpreting the contents of this text, the second chapter of this introductory section addresses the epidemiology of physical activity. Subsequent sections address the effects of physical activity on mental health; knowledge gathered using psychobiological perspectives; behavioral factors that affect exercise motivation; the benefits of physical activity in special populations, including individuals with physical disabilities, older adults, and cancer patients; and promising areas for additional investigation.
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