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Physical Activity for Obese Children and Adults
C H A P T E R
31 Physical Activity for Obese Children and Adults Ross Andersen and Catherine Sabiston Department of Kinesiology and Physical Education, McGill University, Montreal, Canada
o u t l i n e 31.1 Introduction
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31.2 Adults and Physical Activity
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31.3 Physical Activity and Young People 392 31.4 Linking Physical Activity and Obesity 393 31.4.1 Sedentary Activities and Obesity 393 31.4.2 Lifestyle Physical Activity 393 31.5 The Model 31.5.1 Environmental Factors 31.5.2 Self-perceptions, Attitudes and Beliefs
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31.1 Introduction The obesity epidemic has become one the leading health problems in developed countries around the world. This is a public health challenge, and countries such as Canada, Brazil and Mexico are experiencing dramatic increases in the prevalence of obesity. Recent data from the National Center
Obesity Prevention: The Role of Brain and Society on Individual Behavior
31.5.3 Social Context
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31.6 Supporting Overweight Individuals in Overcoming real and/or Perceived Barriers to Physical Activity 397 31.7 Outcomes 31.7.1 Physical Outcomes 31.7.2 Psycho-emotional Outcomes 31.7.3 Social Outcomes
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31.8 Fit or Fat
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31.9 Conclusion
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for Health Statistics (NCHS) show that more than 33 percent of Americans are overweight, and 34 percent are obese (Ogden et al., 2006). More than 6 percent are “extremely” obese. In the US, over one-third of adults (or 72 million people) were classified as obese in 2005–2006, as reported by the NCHS (Ogden et al., 2006). The causes of the obesity epidemic are complex and multifaceted. Clearly, at a population
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level, an energy imbalance is necessary for such widespread increases in body mass index (BMI) to occur. While much has been written about the increased energy intake as the root cause of the epidemic, it is critical to examine the energy expenditure component of the energy balance equation at the same time.
31.2 Adults and physical activity The Surgeon General has reported that a sedentary lifestyle is hazardous to our health, and a growing body of scientific evidence supports recommendations of increasing physical activity to lose weight and maintain good health (Hagan et al., 1986; Klem et al., 1997; Schoeller, 1999; Department of Health and Human Services and US Department of Agriculture, 2005). Despite this knowledge, few adults perform enough physical activity to derive health benefits from it. Most exercise scientists agree that performing at least three bouts of vigorous exercise per week can result in significant health benefits (Haskell et al., 2009). Recently, it has become apparent that the health benefits of physical activity may be achieved at intensities that are lower than those traditionally recommended. Many countries are now encouraging people to accumulate moderate intensity activity throughout the day if they cannot exercise vigorously. The American College of Sports Medicine has recommended that obese individuals accumulate between 200 and 300 minutes of moderate intensity physical activity per week to enhance long-term weight management (Jakicic et al., 2001). This is similar to the recommendation from the Institute of Medicine (IOM) that suggests doing 60 minutes of moderate intensity physical activity per day for weight management (Institute of Medicine, 2002). The International Association for the Study of Obesity (IASO) also advocates 45–90 minutes of
physical activity per day to control body weight (Saris et al., 2003). Nonetheless, obese adults are more likely to be sedentary and not participate in leisure time activity than are their leaner counterparts (Shields and Tremblay, 2008). A recent report found that 19 percent of obese men and only 16 percent of obese women met minimum public health recommendations for physical activity (Centers for Disease Control and Prevention (CDC), 2000). Moreover, in community settings, obese individuals are more likely to choose passive versus active options to ambulate and commute (Andersen et al., 2006). It is paradoxical that 62 percent of obese men and 57 percent of obese women report attempting to use physical activity to lose weight (CDC, 2000).
31.3 Physical activity and young people The World Health Organization (WHO) recom mends that school-age children engage in moderate to vigorous physical activity for at least 60 minutes per day (World Health Organization, 2009). Appropriate physical activity may help children better manage their weight, and has been associated with the promotion of healthy development (Floriani and Kennedy, 2008). Despite the numerous physiological and psychological benefits of active living for young people, levels of physical activity are decreasing around the globe. The following outlines key reasons why physical activity has been engineered out of many young people’s lives: more opportunities for sedentary leisure time (television, Internet, video games); lack of time; greater pressure for academic performance and increased amounts of homework; less recess, intramural and after-school sports in the schools; lack of safe places to exercise; reduced active commuting to and from school; changes in neighborhood design that result in reduced physical activity; increased parental concerns
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31.4 Linking physical activity and obesity
about child safety; unskilled children not being encouraged to remain in sports activity; unskilled children feeling embarrassed to exercise in front of peers; and more dual-career families (Floriani and Kennedy, 2007, 2008).
3.4 3.1 29.2
Watching TV Watching time-shifted TV
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Time on the Internet
31.4 Linking physical activity and obesity Inactivity and overweight/obesity have been identified as significant health risks (Physical Activity Guidelines Advisory Committee, 2008). While inactivity and overweight/obesity do not necessarily co-occur, they have been linked. Increasing physical activity has been identified as one way of battling the obesity epidemic (Wing, 1999). We propose that increasing physical activity, in particular lifestyle activity, and reducing time spent in sedentary activities are strategies to help offset the public health risks associated with obesity across the lifespan.
31.4.1 Sedentary activities and obesity A direct association between the hours of television watched and BMI or body fatness in American children has been reported (Andersen et al., 1998a). Others have found that time spent playing video games, in front of a computer and, to lesser extent, reading are also related to an increased prevalence of obesity. This link has been made primarily as a result of the low energy expenditure that occurs during sedentary behaviors. It has also been reported that children who watch 5 or more hours of television per day consume on average 200 kcal per day more than their counterparts who watch 1 hour or less of television per day (Crespo et al., 1998). We suspect that television watching may be a cue to eat for many overweight individuals. Recent data from the Neilson Organization (Figure 31.1) have reported that the average American adult watches over 127 hours of television and browses
Watching video on the Internet
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Watching video on a mobile phone
Figure 31.1 Average monthly hours among American adults doing sedentary activities. Source: Nielson Three Screen Report (2008).
the Internet for 26 hours per month. This represents 22 percent of all hours each month – or 39 percent of typical waking hours are spent in front of a screen. Epstein and colleagues (1997) have developed a treatment for sedentary overweight children that encourages them to reduce the time spent engaging in sedentary activities. Children in these studies are given television allowances and are taught to limit the time they spend on the Internet and playing video games. They are also encouraged to look for opportunities to walk or cycle to and from school. While this model has not been tested in adult populations, it may offer promising results.
31.4.2 Lifestyle physical activity Many investigators have also demonstrated that traditional vigorous exercise may not be the optimal way to help sedentary overweight individuals adopt more active lifestyles (Andersen et al., 1998b, 1999; Jakicic et al., 2001). This is particularly true if they do not enjoy or are not able to perform traditional vigorous, continuous exercise. Lifestyle physical activity encourages patients to look for opportunities to accumulate moderate-intensity physical activity throughout the
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day (Andersen, 1999; Andersen et al., 1999). It has been found that sedentary overweight adults often feel that this may be a do-able way to begin increasing their physical activity. Moreover, patients who begin increasing their activity with lifestyle activity seem to gain confidence in their ability to exercise, and over time begin to transition into a more traditional, moderate-to-vigorous exercise program. Jakacic and colleagues have also found that accumulating short 10-minute bouts of aerobic exercise may offer obese adults a suitable alternative to traditional uninterrupted exercise (Jakicic et al., 1999). This is important, given that a perceived lack of time remains the top reason that sedentary overweight individuals report for not participating in regular activity.
31.5 The model The model depicted in Figure 31.2 has been developed by the authors to summarize physical activity motivation and health behavior change models – e.g., the expectancy–value model (Eccles, 1983); self-determination theory (Deci and Ryan, 1985); social cognitive theory (Bandura, 1997); the social-ecological model (Bronfenbrenner, 1977); and theory of planned behavior (Ajzen and Madden, 1986) – as well as empirical evidence demonstrating direct and mediating relationships as outlined. This non-linear model describes the individual, social and environmental factors that influence physical activity in overweight individuals. Positive changes, as a result of physical activity
Weight status Antecedents Self-perceptions, attitudes, beliefs
Physical environment
Social context
Physical activity Moderators -diet -sedentary behavior
Psychoemotional
Physical/ biological Outcomes
Figure 31.2 Model relating weight status and physical activity.
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31.5 The model
intervention, have also impacted these factors; hence the feedback loop depicted in the model (Kahn et al., 2002; Gallagher et al., 2006). The outcomes of physical activity are classified as having psycho-emotional, social and physical underpinnings.
31.5.1 Environmental factors The relationship between weight status and physical activity levels may be explained in part by environmental factors. For example, neighborhood features, such as lower perceptions of safety and characteristics that preclude walking, have been linked to higher body weight. Neighborhoods with higher walkability indices (grid-like structures with less cul-de-sacs and more street connectivity and intersections, the presence of sidewalks, and perceptions of safety) tend to promote physical activity and support a greater number of active transportation than low-walkability neighborhoods (Gordon-Larsen et al., 2006; Smith et al., 2008; Spence et al., 2008). There is a lower prevalence of overweight in these safe and walkable neighborhoods, which tend to be located in more urban living areas (Joens-Matre et al., 2008). Notwithstanding the walkability index, there is also lower prevalence of overweight in urban compared to rural areas. Furthermore, access to facilities and opportunities can be a barrier to increased physical activity levels for overweight individuals (Gallagher et al., 2006; Holt et al., 2008). Strategies to increase safe play spaces and to provide specific sports and physical activity programs to overweight youth appear to be effective in reducing weight and enhancing health and well-being (Farley et al., 2007; Weintraub et al., 2008). Greater (or increased awareness of) opportunities for physical activity among overweight individuals are necessary. One approach may be to promote lifestyle physical activity. Integrating 30–60 minutes, 5–7 days per week, of lifestyle physical activity has adaptive physical and
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psychological outcomes, including reduced anxiety and depression, increased self-esteem, and reduced fatigue (Andersen et al., 1999). Environmental manipulations, such as simple signs and visual prompts encouraging physical activity (for example, taking the stairs instead of the elevator), appear to be beneficial in increasing lifestyle physical activity (Andersen et al., 1998b; Rees, 2007). Other environmental attributes include the development and implementation of institutional policies, and community-level program development. Physical activity opportunities that enable overweight individuals to exercise together may also be particularly important.
31.5.2 Self-perceptions, attitudes and beliefs Understanding the individual-level factors that are linked to physical activity participation among overweight/obese individuals is challenging and overwhelming. Nonetheless, most emphasis has been placed on self-perceptions such as self-concept, self-efficacy, perceptions of competence, enjoyment, intrinsic motivation and interest in physical activity, and perceived barriers and drawbacks of exercising. Specifically, individuals who have weaker perceptions of the physical self and higher weight concerns are more likely to use physical activity as weight management (Page and Fox, 1997). Self-esteem tends to be directly associated with physical activity levels (Dunn et al., 2001), and overweight individuals may be more likely to report lower self-esteem than their healthyweight counterparts (Pesa et al., 2000). Perceptions of competence/physical activity self-efficacy and/or beliefs of enjoyment and interest have shown some of the strongest associations to behavior both in theory (Bandura, 1997; Eccles and Wigfield, 2002) and in empirical evidence (Deci and Ryan, 1985; van der Horst et al., 2007; Sabiston and Crocker, 2008). Unfortunately, overweight persons report lower
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perceptions of competence and generally feel less pleasure while exercising, and thus exhibit lower enjoyment beliefs (Garcia-Bengoechea et al., 2010). Once physically active, overweight individuals have reported empowering increases in perceptions of competence and self-concept that foster increased physical activity participation and greater confidence to try new activities (Gallagher et al., 2006; Sabiston et al., 2009). This relationship is illustrated in Figure 31.2 by the circular nature of the model. Research from the Australian Longitudinal Study on Women’s Health reports that depressive symptoms are higher among women who are overweight or obese as well as among more sedentary individuals (Ball et al., 2008). Physical activity can promote and maintain mental health by protecting individuals from depression and anxiety (Paffenberger et al., 1994; Motl et al., 2004). Physical activity may also be used as a treatment for non-clinical depressive symptoms and diagnosed depression (North et al., 1990; Craft and Landers, 1998). Overweight individuals face unique socialcontext barriers, such as stereotypes, embarrassment, body-image concerns, time barriers and lack of motivation, and obstacles (e.g., weather, access, support) are commonly reported (Godin et al., 1986; Gallagher et al., 2006). Efforts aimed at reducing the perception and/or existence of these barriers for overweight individuals are necessary. Simply engaging in structured physical activity programs seems to reduce the extent of reported barriers (Gallagher et al., 2006), thus providing some justification for the circular nature of the model.
31.5.3 Social context The social context includes others’ beliefs and behaviors regarding physical activity and weight status. Most individuals need to perceive strong social-normative beliefs about exercising in order to engage in the behavior. Drawing
from the sport and exercise literature, social support primarily consists of the network of providers (who) as well as the types of strategies provided (what) (Rees, 2007). For example, having physically active friends, co-workers and family members who can act as role models has a positive impact on physical activity levels for youth and adults, independent of weight status (Sallis et al., 2000). In fact, overweight youth reported that a barrier to their activity levels was not having someone with whom to engage in physical activities (Zabinski et al., 2003). The functions of social support are important factors in promoting physical activity throughout the lifespan for overweight individuals (Trost et al., 2003, Sabiston et al., 2009). Providers of physical activity-related support may provide information (i.e., advice, suggestions and guidance), emotional strategies such as encouragement and praise, esteem functions (i.e., comfort, concern, and care), and tangible support, which includes providing instrumental and practical assistance (such as gym memberships, equipment, etc.). Socially-created barriers, such as stereotypes that overweight individuals are lazy and unmotivated, and weight discrimination/fat biases may act as barriers to physical activity among overweight individuals (Ball et al., 2000; Zabinski et al., 2003; Davison et al., 2008). Furthermore, overweight individuals who internalize these stereotypes themselves are at risk of poor psychosocial functioning and wellbeing (Davison et al., 2008). Overweight girls and women report embarrassment and body image as additional factors hindering their engagement in physical activity (Hooper and Veneziano, 1995; Treasure et al., 1998; Zabinski et al., 2003). Taken together, social support and a strong social-normative belief can promote physical activity, whereas stereotypes and fat stigmatiz ation may act as deterrents to activity among overweight individuals. In addition to the direct effect that social factors may have on physical
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31.7 Outcomes
activity, they also indirectly influence behavior by affecting an individual’s self-perceptions, attitudes and beliefs about exercise (Brustad, 1996). Taken together, the factors outlined in the model are strong correlates of physical activity behavior. The following outlines ways to support overweight individuals in overcoming barriers to being physically active, and in turn increase the likelihood of engaging in physical activity.1 1. Since changing the physical environment is difficult and costly, it is important to help overweight individuals become aware of available opportunities and reframe their conception of environmental factors. An intention implementation plan has been demonstrated to be very efficient in overcoming barriers. Individuals write down barriers that they encounter or anticipate encountering in their neighborhood, and prepare a plan for what they will do when this barrier is encountered. It usually reads as follows: “If... [barrier], then... [plan]”. 2. Using visual cues and prompts to remind individuals to exercise is also an effective
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strategy. The key is to use personal photos and affirmations, rather than unrealistic magazine photos or impersonal slogans. 3. Seeking social support and using available resources, whether a trainer in a gym, an Internet website, or a colleague or friend, has been found to be helpful. Another strategy is identifying exercise partners. 4. Highlighting the positive emotions that result from exercise, rather than those of guilt, shame and embarrassment that keep individuals from being physically active, can also help overcome barriers. 5. Finally, it is crucial to help individuals set SMART (Specific, Measureable, Attainable, Realistic, and Time-based) goals.
31.5.4 Outcomes Physical activity confers physical, mental (psychological and emotional) and social health benefits (World Health Organization, 2009). The physical benefits of exercise include (but are not limited to) the reduced risk of cardiovascular disease, ischemic stroke, diabetes, various
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In order for healthcare providers to help overweight patients adopt more active lifestyles, it is always helpful to know how much physical activity they are currently engaging in. Direct measures of physical activity tend to be the most accurate, since they do not rely on patient recall. While unpractical for most clinical settings, the best technique to measure physical activity remains the water technique (i.e., the individual consumes a stable isotope to examine hydrogen and carbon utilization over a period of time to calculate total energy expenditure). A more practical approach may be to use motion sensors (i.e., accelerometers and pedometers). The accelerometers can measure activity in two or three different planes, using sensors that can reflect speed and intensity of effort. They are more costly (approximately US $350) than pedometers, and are often used more commonly in research settings. In contrast, pedometers are available in most sporting goods stores and essentially measure the number of steps taken per day. Approximating the individual’s stride length and multiplying this value by the number of steps taken will calculate daily walking distance. Good quality devices can be purchased for about US $30, and they have been found to provide motivation to patients. Patients should be encouraged to wear a pedometer for a week to get a baseline activity assessment. They should then strive to increase their daily step count by 1000 steps per day each week until they reach 10,000 steps per day. Finally, questionnaires have also been used to assess physical activity. Several valid and reliable questionnaires are available for use in a written format or administered by a trained clinician. As with all self-report questionnaires, an inability to recall past physical activity episodes can lead to problems of inaccuracy and lack of precision.
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types of cancers, and osteoporosis (Ford and Mokdad, 2008). Men and women who are physically active also have a 20–35 percent reduced relative risk of death (Macera and Powell, 2001; Hu et al., 2004; Myers et al., 2004). Moreover, physical activity leads to improved body composition (i.e., reduction in adiposity and weight control), which in turn further improves the already mentioned physical health outcomes (Tremblay et al., 1990; Warburton et al., 2006).
31.5.5 Psycho-emotional outcomes As stated above, overweight individuals often have poorer psychological profiles than their healthy-weight counterparts and chronically ill individuals (Ball et al., 2008). Physical activity benefits are often most effective for those individuals who have the worst mentalhealth profiles – providing justification for the enhanced need to help overweight individuals become more physically active. Additionally, increases in physical activity may be protective against depressive symptoms (Fox, 2000). In addition to alleviating mental health problems such as depression and anxiety, physical activity also appears to influence stress levels. Research has shown that physically active individuals are more likely to have dampened stress reactions in general. If they experience stressful events, their stress levels tend to return to baseline faster than those of individuals who are not physically active (Buckworth and Dishman, 2002; Boutcher et al., 2009). Physical activity can also be a coping mechanism used to deal with stress. Since overweight individuals tend to have lower levels of self-esteem, greater bodyimage disturbance and overall heightened selfpresentation issues, physical activity can also confer positive effects on these body-related affects and cognitions (Treasure et al., 1998). Specifically, when weight loss or perceptions of increased aerobic capacity and muscular strength are reported as a result of physical activity participation,
individuals tend to have increases in perceptions of physical self-concept. This association is depicted by the feedback loop in the model. Furthermore, with the identity shift that may be experienced as a result of regular physical activity participation, there may be the opportunity for overweight individuals to experience psychological growth. Whereas the concept of positive psychological growth has been studied in populations who have suffered trauma (i.e., cancer, death, abuse) (Tedeschi and Calhoun, 2004), it can be speculated that overweight individuals who lose weight and/or become physically active also experience this growth. The concept suggests that as overweight individuals struggle with their weight and attempt to become physically active, changes to their physical self-concept and perceptions (i.e., feelings of being more muscular, having more energy and endurance, and reduced weight) will lead to psychological growth (Tedeschi and Calhoun, 2004). This means realizing new possibilities, developing personal strength and empower ment, a new appreciation for life, and new or stronger relationships with others (Tedeschi and Calhoun, 2004). More research is needed to better understand the experiences of psychological growth for overweight individuals.
31.5.6 Social outcomes The idea of developing new or stronger relationships with others through exercise is the final outcome of the model. Generally, individuals appear to benefit most from group-based interventions as compared to individual, home-based programs or information/education efforts (van der Horst et al., 2007). Regardless of the nature of physical activity, be it groups or individual participation, the behavior appears to enhance social normative beliefs, and provide individuals with greater support networks and the ability to seek social support when needed. Moreover, when accomplished in groups, it enhances connectedness among participants (Kayman et al., 1990).
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31.6 Fit or fat It is well known that excess weight and physical inactivity are independently related to mortality. However, many public health scientists have argued that it is important to consider fitness and levels of physical activity when evaluating the health risks of obesity. A recent report examined the association between physical activity and overweight status to evaluate whether activity can reduce the adverse impact of a higher BMI on coronary heart disease (CHD) (Weinstein et al., 2008). Women were classified as active if they met public health guidelines and engaged in 30 minutes or more of moderate activity most days of the week, including brisk walking or jogging. Women who engaged in less were classified as inactive. After adjusting for confounding variables, inactive normal-weight women had a slightly (8 percent) higher risk of CHD than those who were fit and active. Conversely, the risk of developing CHD was 54 percent more likely among overweight women and 88 percent more likely for obese women compared to their normal-weight active counterparts. The data show that overweight and obese women can considerably alter the risk of heart disease by remaining physically active. This is particularly important for those obese individuals who may not be ready to lose weight. However, an active lifestyle did not entirely eliminate the risks of obesity, which reinforces the importance of active living combined with maintaining a healthy body weight.
31.7 Conclusion In conclusion, the obesity epidemic is now one of the greatest public health challenges facing healthcare professionals in developed countries around the globe. In addition to sensible meal planning, it is critical to examine strategies
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to encourage both youth and adult patients to adopt more active lifestyles and reduce sedentary activities. Accumulating appropriate amounts of activity may help to promote healthier living, even if weight status is not changed.
References Ajzen, I., & Madden, T. J. (1986). Prediction of goal-directed behavior: Attitudes, intentions, and perceived behavioral control. Journal of Experimental Social Psychology, 22, 453–474. Andersen, R. E. (1999). Exercise, an active lifestyle, and obesity: Making the exercise prescription work. Physician Sports Medicine, 27, 41–50. Andersen, R. E., Crespo, C. J., Bartlett, S. J., Cheskin, L. J., & Pratt, M. (1998a). Relationship of physical activity and television watching habits among US children with body weight and level of fatness: Results from the third national health and nutrition examination survey. Journal of the American Medical Association, 279, 938–942. Andersen, R. E., Franckowiak, S. C., Snyder, J., Bartlett, S. J., & Fontaine, K. R. (1998b). Can inexpensive signs encourage the use of stairs? Results from a community intervention. Annals of Internal Medicine, 129, 363–369. Andersen, R. E., Wadden, T. A., Bartlett, S. J., Zemel, B., Verde, T. J., & Franckowiak, S. C. (1999). Effects of lifestyle activity vs structured aerobic exercise in obese women. Journal of the American Medical Association, 281, 335–340. Andersen, R. E., Franckowiak, S. C., Zuzak, K. B., Cummings, E. S., Bartlett, S. J., & Crespo, C. J. (2006). Effects of a culturally sensitive sign on the use of stairs in African American commuters. Sozial- und Praventivmedizin, 51, 373–380. Ball, K., Crawford, D., & Owen, N. (2000). Too fat to exercise? Obesity as a barrier to physical activity. Australian and New Zealand Journal of Public Health, 24, 331–333. Ball, K., Burton, N. W., & Brown, W. J. (2008). A prospective study of overweight, physical activity, and depressive symptoms in young women. Obesity, 17, 66–71. Bandura, A. (1997). Self-efficacy: The exercise of control. New York, NY: Freeman. Boutcher, S. H., Nugent, F. W., McLaren, P. F., & Weltman, A. L. (2009). Heart period variability of trained and untrained men at rest and during mental challenges. Psychophysiology, 35, 16–22. Bronfenbrenner, U. (1977). Toward an experimental ecology of human development. The American Psychologist, 32, 513–531. Brustad, R. J. (1996). Attraction to physical activity in urban schoolchildren: Parental socialization and gender influences. Research Quarterly for Exercise and Sport, 67, 316–323.
1. From Brain to Behavior
400
31. Physical Activity and obesity
Buckworth, J., & Dishman, R. K. (2002). Stress. In J. Buckworth & R. K. Dishman (Eds.), Exercise psychology (pp. 75–89). Champaign, IL: Human Kinetics. Craft, L. L., & Landers, D. M. (1998). The effect of exercise on clinical depression and depression resulting from mental illness: A meta-analysis. Journal of Sport & Exercise Psychology, 20, 339–357. Crespo, C. J., Andersen, R. E., Pratt, M., Snelling, A. M., & Franckowiak, S. (1998). Obesity and its relation to physical activity and television watching among US children. Medicine and Science in Sports and Exercise, 30(Suppl. 5), S80. Davison, K. K., Schmalz, D. L., Young, L. M., & Birch, L. L. (2008). Overweight girls who internalize fat stereotypes report low psychosocial well-being. Obesity, 16, S30–S38. Deci, E. L., & Ryan, R. M. (1985). Intrinsic motivation and selfdetermination in human behavior. New York, NY: Plenum. Department of Health and Human Services and US Department of Agriculture. (2005). Dietary Guidelines for Americans. Online. Available: http://healthierus.gov/ dietaryguidelines/. Dunn, A. L., Madhukar, T., & O’Neil, H. A. (2001). Physical activity dose-response effects on outcomes of depression and anxiety. Medicine & Science in Sports & Exercise, 33, S587–S597. Eccles, J. S. (1983). Expectancies, values, and academic behavior. In J. T. Spence (Ed.), Achievement and achievement motives (pp. 75–146). San Francisco, CA: W. H. Freeman. Eccles, J. S., & Wigfield, A. (2002). Motivational beliefs, values, and goals. Annual Review of Psychology, 53, 109–132. Epstein, L. H., Saelens, B. E., Myers, M. D., & Vito, D. (1997). Effects of decreasing sedentary behaviors on activity choice in obese children. Health Psychology, 16, 107–113. Farley, T. A., Meriwether, R. A., Baker, E. T., Watkins, L. T., Johnson, C. C., & Webber, L. S. (2007). Safe play spaces to promote physical activity in inner-city children: Results form a pilot study of an environmental intervention. American Journal of Public Health, 97, 1625–1631. Floriani, V., & Kennedy, C. (2007). Promotion of physical activity in primary care for obesity treatment/prevention in children. Current Opinion in Pediatrics, 19(1), 99–103. Floriani, V., & Kennedy, C. (2008). Promotion of physical activity in children. Current Opinion in Pediatrics, 20(1), 90–95. Ford, E. S., & Mokdad, A. H. (2008). Epidemiology of obesity in the Western Hemisphere. The Journal of Clinical Endocrinology and Metabolism, 93, S1–S8. Fox, K. R. (2000). The effects of exercise on self-perceptions and self-esteem. In S. Biddle, K. R. Fox, & S. Boutcher (Eds.), Physical activity and psychological well-being (pp. 88–117). New York, NY: Routledge. Gallagher, K. I., Jakicic, J. M., Napolitano, M. A., & Marcus, B. (2006). Psychosocial factors related to physical activity and weight loss in overweight women. Medicine and Science in Sports and Exercise, 38, 971–980.
Garcia-Bengoechea, E., Sabiston, C. M., Ahmed, R., & Faroush, M. (2010). Exploring links to unorganized and organized physical activity during adolescence: the role of gender, socioeconomic status, weight status and enjoyment of physical education. Research Quarterly in Exercise and Sport, 81, 7–16. Godin, G., Shepard, R. J., & Golantonio, A. (1986). The cognitive profile of those who intend to exercise but do not. Public Health Reports, 101, 521–526. Gordon-Larsen, P., Nelson, M. C., Page, P., & Popkin, B. M. (2006). Inequality in the built environment underlies key health disparities in physical activity and obesity. Pediatrics, 117, 417–424. Hagan, R. D., Upton, S. J., Wong, L., & Whittam, J. (1986). The effects of aerobic conditioning and/or caloric restriction in overweight men and women. Medicine and Science in Sports and Exercise, 18, 87–94. Haskell, W. L., Blair, S. N., & Hill, J. O. (2009). Physical activity: Health outcomes and importance for public health policy. Preventive Medicine, 49(4), 280–282. Holt, N. L., Moylan, B. A., Spence, J. C., Lenk, J. M., Sehn, Z. L., & Ball, G. D. C. (2008). Treatment preferences of overweight youth and their parents in Western Canada. Qualitative Health Research, 18, 1206–1219. Hooper, J., & Veneziano, L. (1995). Distinguishing starters from non-starters in an employee physical activity inventive program. Health Education Quarterly, 22, 49–60. Hu, F. B., Willett, W. C., Li, T., Stampfer, M. J., Colditz, G. A., & Manson, J. E. (2004). Adiposity compared with physical activity in predicting mortality among women. New England Journal of Medicine, 351, 2694–2703. Institute of Medicine. (2002). Dietary reference intakes for energy, carbohydrates, fiber, fat, protein and amino acids (macronutrients). Washington, DC: National Academies Press. Jakicic, J. M., Winters, C., Lang, W., & Wing, R. R. (1999). Effects of intermittent exercise and use of home exercise equipment on adherence, weight loss, and fitness in overweight women: A randomized trial. Journal of the American Medical Association, 282, 1554–1560. Jakicic, J. M., Clark, K., Coleman, E., Donnelly, J. E., Foreyt, J., Melanson, E., Volek, J., & Volpe, S. L. (2001). American college of sports medicine position stand. Appropriate intervention strategies for weight loss and prevention of weight regain for adults. Medicine and Science in Sports and Exercise, 33, 2145–2156. Joens-Matre, R. R., Welk, G. J., Calabro, M. A., Russell, D. W., Nicklay, E., & Hensley, L. D. (2008). Rural–urban differences in physical activity, physical fitness, and overweight prevalence of children. The Journal of Rural Health, 24, 49–54. Kahn, E. B., Ramsey, L. T., Brownson, R. C., Heath, G. W., Howze, E. H., Powell, K. E., Stone, E. J., Rajab, M. W., & Corso, P. (2002). The effectiveness of interventions to
1. From Brain to Behavior
references
increase physical activity: A systematic review. American Journal of Preventive Medicine, 22, 73–107. Kayman, S., Bruvold, W., & Stern, J. S. (1990). Maintenance and relapse after weight loss in women: Behavioral aspects. The American Journal of Clinical Nutrition, 52, 800–807. Klem, M. L., Wing, R. R., McGuire, M. T., Seagle, H. M., & Hill, J. O. (1997). A descriptive study of individuals successful at long-term maintenance of substantial weight loss. The American Journal of Clinical Nutrition, 66, 239–246. Macera, J., & Powell, K. E. (2001). Population attributable risk: Implications of physical activity dose. Medicine and Science in Sport and Exercise, 33, S635–S639. Motl, R. W., Birnbaum, A. S., Kubik, M. Y., & Dishman, R. K. (2004). Naturally occurring changes in physical activity are inversely related to depressive symptoms during early adolescence. Psychosomatic Medicine, 66, 336–342. Myers, K., Kaykha, A., Gergor, S., Abella, J., Zaheer, N., Lear, S., Yamazaki, T., & Froelicher, V. (2004). Fitness versus physical activity patterns in predicting mortality in men. American Journal of Medicine, 117, 912–918. North, T. C., McCullagh, P., & Tran, Z. V. (1990). Effect of exercise on depression. Exercise and Sport Sciences Reviews, 18, 379–415. Ogden, C. K., Carroll, M. D., Curtin, L. R., McDowell, M. A., Tabak, C. J., & Flegal, K. M. (2006). Prevalence of overweight and obesity in the United States, 1999–2004. Journal of the American Medical Association, 295(13), 1549–1555. Paffenberger, R. S., Lee, I. M., & Leung, R. (1994). Physical activity and personal characteristics associated with depression and suicide in American college men. Acta Psychiatrica Scandinavica, S377, 16–22. Page, A., & Fox, K. R. (1997). Adolescent weight management and the physical self. In K. R. Fox (Ed.), The physical self: From motivation to well-being (pp. 229–256). Champaign, IL: Human Kinetics. Pesa, J. A., Syre, T. R., & Jones, E. (2000). Psychosocial differences associated with body weight among female adolescents: The importance of body image. Journal of Adolescent Health, 26, 330–337. Physical Activity Guidelines Advisory Committee. (2008). Physical activity guidelines advisory committee report, 2008. Washington, DC: US Department of Health and Human Services. Rees, T. (2007). Influence of social support on athletes. In S. Jowett & D. Lavallee (Eds.), Social psychology in sport (pp. 223–231). Champaign, IL: Human Kinetics. Sabiston, C. M., & Crocker, P. R. E. (2008). Exploring selfperceptions ad social influences as correlates of adolescent leisure-time physical activity. Journal of Sport & Exercise Psychology, 30, 3–22. Sabiston, C. M., McDonough, M. H., Sedgwick, W. A., & Crocker, P. R. (2009). Muscle gains and emotional strains: conflicting experiences of change among overweight
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women participating in an excercise intervention program. Qualitative Health Research, 19, 466–480. Sallis, J. F., Prochaska, J. J., & Taylor, W. C. (2000). A review of correlates of physical activity of children and adolescents. Medicine and Science in Sport and Exercise, 32, 963–975. Saris, W. H., Blair, S. N., van Baak, M. A., Eaton, S. B., Davies, P. S., Di Pietro, L., et al. (2003). How much physical activity is enough to prevent unhealthy weight gain? Outcome of the IASO 1st Stock Conference and consensus statement. Obesity Reviews, 4, 101–114. Schoeller, D. A. (1999). Recent advances from application of doubly labeled water to measurement of human energy expenditure. The Journal of Nutrition, 129, 1765–1768. Shields, M., & Tremblay, M. S. (2008). Sedentary behaviour and obesity. Health Reports, 19, 19–30. Smith, K., Brown, B., Yamada, I., Kowaleski-Jones, L., Zick, C., & Fan, J. (2008). Walkability and body mass index: density, design, and new diversity measures. American Journal of Preventive Medicine, 35, 237–244. Spence, J. C., Cutumisu, N., Edwards, J., & Evans, J. (2008). Influence of neighbourhood design and access to facilities on overweight and obesity among preschool children. International Journal of Pediatric Obesity, 3, 109–116. Tedeschi, R. G., & Calhoun, L. G. (2004). Posttraumatic growth: Conceptual foundations and empirical evidence. Psychological Inquiry, 15, 1–18. Treasure, D. C., Lox, C. L., & Lawton, B. R. (1998). Determinants of physical activity in a sedentary, obese female population. Journal of Sport & Exercise Psychology, 20, 218–224. Tremblay, A., Despres, J. P., Leblanc, C., Craig, C. L., Ferris, B., Stephens, T., & Bouchard, C. (1990). Effect of intensity of physical activity on body fatness and fat distribution. American Journal of Clinical Nutrition, 51, 153–157. Trost, S. G., Sirard, J., Dowda, M., Pfeiffer, K. A., & Pate, R. R. (2003). Physical activity in overweight and non overweight preschool children. International Journal of Obesity and Related Metabolic Disorders, 27, 834–839. van der Horst, K., Paw, M. J., Twisk, J. W. R., & Mechelen, W. (2007). A brief review on correlates of physical activity and sedentariness in youth. Medicine & Science in Sports and Exercise, 39, 1241–1250. Warburton, D. E. R., Whitney Nicol, C., & Bredin, S. D. (2006). Health benefits of physical activity: The evidence. Journal of the American Medical Association, 174, 801–809. Weinstein, A. R., Sesso, H. D., Lee, I. M., Rexrode, K. M., Cook, N. R., Manson, J. E., et al. (2008). The joint effects of physical activity and body mass index on coronary heart disease risk in women. Archives of Internal Medicine, 168, 884–890. Weintraub, D. L., Tirumalai, E. C., Haydel, F., Fujimoto, M., Fulton, J. E., & Robinson, T. N. (2008). The Stanford sports to prevent obesity randomized trial (SPORT). Archives of Pediatric Adolescent Medicine, 162, 232–237.
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Wing, R. R. (1999). Physical activity in the treatment of adulthood overweight and obesity: Current evidence and research issues. Medicine & Science in Sports & Exercise, 31, S547–S552. World Health Organization. (2009). Global strategy on diet, physical activity and health. Geneva: WHO.
Zabinski, M. F., Saelens, B. E., Stein, R. I., Hayden-Wade, H. A., & Wilfley, D. E. (2003). Overweight children’s barriers to and support for physical activity. Obesity Research, 11, 238–246.
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31 Physical Activity for Obese Children and Adults Ross Andersen and Catherine Sabiston Department of Kinesiology and Physical Education, McGill University, Montreal, Canada
o u t l i n e 31.1 Introduction
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31.2 Adults and Physical Activity
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31.3 Physical Activity and Young People 392 31.4 Linking Physical Activity and Obesity 393 31.4.1 Sedentary Activities and Obesity 393 31.4.2 Lifestyle Physical Activity 393 31.5 The Model 31.5.1 Environmental Factors 31.5.2 Self-perceptions, Attitudes and Beliefs
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31.1 Introduction The obesity epidemic has become one the leading health problems in developed countries around the world. This is a public health challenge, and countries such as Canada, Brazil and Mexico are experiencing dramatic increases in the prevalence of obesity. Recent data from the National Center
Obesity Prevention: The Role of Brain and Society on Individual Behavior
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31.6 Supporting Overweight Individuals in Overcoming real and/or Perceived Barriers to Physical Activity 397 31.7 Outcomes 31.7.1 Physical Outcomes 31.7.2 Psycho-emotional Outcomes 31.7.3 Social Outcomes
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for Health Statistics (NCHS) show that more than 33 percent of Americans are overweight, and 34 percent are obese (Ogden et al., 2006). More than 6 percent are “extremely” obese. In the US, over one-third of adults (or 72 million people) were classified as obese in 2005–2006, as reported by the NCHS (Ogden et al., 2006). The causes of the obesity epidemic are complex and multifaceted. Clearly, at a population
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level, an energy imbalance is necessary for such widespread increases in body mass index (BMI) to occur. While much has been written about the increased energy intake as the root cause of the epidemic, it is critical to examine the energy expenditure component of the energy balance equation at the same time.
31.2 Adults and physical activity The Surgeon General has reported that a sedentary lifestyle is hazardous to our health, and a growing body of scientific evidence supports recommendations of increasing physical activity to lose weight and maintain good health (Hagan et al., 1986; Klem et al., 1997; Schoeller, 1999; Department of Health and Human Services and US Department of Agriculture, 2005). Despite this knowledge, few adults perform enough physical activity to derive health benefits from it. Most exercise scientists agree that performing at least three bouts of vigorous exercise per week can result in significant health benefits (Haskell et al., 2009). Recently, it has become apparent that the health benefits of physical activity may be achieved at intensities that are lower than those traditionally recommended. Many countries are now encouraging people to accumulate moderate intensity activity throughout the day if they cannot exercise vigorously. The American College of Sports Medicine has recommended that obese individuals accumulate between 200 and 300 minutes of moderate intensity physical activity per week to enhance long-term weight management (Jakicic et al., 2001). This is similar to the recommendation from the Institute of Medicine (IOM) that suggests doing 60 minutes of moderate intensity physical activity per day for weight management (Institute of Medicine, 2002). The International Association for the Study of Obesity (IASO) also advocates 45–90 minutes of
physical activity per day to control body weight (Saris et al., 2003). Nonetheless, obese adults are more likely to be sedentary and not participate in leisure time activity than are their leaner counterparts (Shields and Tremblay, 2008). A recent report found that 19 percent of obese men and only 16 percent of obese women met minimum public health recommendations for physical activity (Centers for Disease Control and Prevention (CDC), 2000). Moreover, in community settings, obese individuals are more likely to choose passive versus active options to ambulate and commute (Andersen et al., 2006). It is paradoxical that 62 percent of obese men and 57 percent of obese women report attempting to use physical activity to lose weight (CDC, 2000).
31.3 Physical activity and young people The World Health Organization (WHO) recom mends that school-age children engage in moderate to vigorous physical activity for at least 60 minutes per day (World Health Organization, 2009). Appropriate physical activity may help children better manage their weight, and has been associated with the promotion of healthy development (Floriani and Kennedy, 2008). Despite the numerous physiological and psychological benefits of active living for young people, levels of physical activity are decreasing around the globe. The following outlines key reasons why physical activity has been engineered out of many young people’s lives: more opportunities for sedentary leisure time (television, Internet, video games); lack of time; greater pressure for academic performance and increased amounts of homework; less recess, intramural and after-school sports in the schools; lack of safe places to exercise; reduced active commuting to and from school; changes in neighborhood design that result in reduced physical activity; increased parental concerns
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about child safety; unskilled children not being encouraged to remain in sports activity; unskilled children feeling embarrassed to exercise in front of peers; and more dual-career families (Floriani and Kennedy, 2007, 2008).
3.4 3.1 29.2
Watching TV Watching time-shifted TV
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Time on the Internet
31.4 Linking physical activity and obesity Inactivity and overweight/obesity have been identified as significant health risks (Physical Activity Guidelines Advisory Committee, 2008). While inactivity and overweight/obesity do not necessarily co-occur, they have been linked. Increasing physical activity has been identified as one way of battling the obesity epidemic (Wing, 1999). We propose that increasing physical activity, in particular lifestyle activity, and reducing time spent in sedentary activities are strategies to help offset the public health risks associated with obesity across the lifespan.
31.4.1 Sedentary activities and obesity A direct association between the hours of television watched and BMI or body fatness in American children has been reported (Andersen et al., 1998a). Others have found that time spent playing video games, in front of a computer and, to lesser extent, reading are also related to an increased prevalence of obesity. This link has been made primarily as a result of the low energy expenditure that occurs during sedentary behaviors. It has also been reported that children who watch 5 or more hours of television per day consume on average 200 kcal per day more than their counterparts who watch 1 hour or less of television per day (Crespo et al., 1998). We suspect that television watching may be a cue to eat for many overweight individuals. Recent data from the Neilson Organization (Figure 31.1) have reported that the average American adult watches over 127 hours of television and browses
Watching video on the Internet
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Watching video on a mobile phone
Figure 31.1 Average monthly hours among American adults doing sedentary activities. Source: Nielson Three Screen Report (2008).
the Internet for 26 hours per month. This represents 22 percent of all hours each month – or 39 percent of typical waking hours are spent in front of a screen. Epstein and colleagues (1997) have developed a treatment for sedentary overweight children that encourages them to reduce the time spent engaging in sedentary activities. Children in these studies are given television allowances and are taught to limit the time they spend on the Internet and playing video games. They are also encouraged to look for opportunities to walk or cycle to and from school. While this model has not been tested in adult populations, it may offer promising results.
31.4.2 Lifestyle physical activity Many investigators have also demonstrated that traditional vigorous exercise may not be the optimal way to help sedentary overweight individuals adopt more active lifestyles (Andersen et al., 1998b, 1999; Jakicic et al., 2001). This is particularly true if they do not enjoy or are not able to perform traditional vigorous, continuous exercise. Lifestyle physical activity encourages patients to look for opportunities to accumulate moderate-intensity physical activity throughout the
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day (Andersen, 1999; Andersen et al., 1999). It has been found that sedentary overweight adults often feel that this may be a do-able way to begin increasing their physical activity. Moreover, patients who begin increasing their activity with lifestyle activity seem to gain confidence in their ability to exercise, and over time begin to transition into a more traditional, moderate-to-vigorous exercise program. Jakacic and colleagues have also found that accumulating short 10-minute bouts of aerobic exercise may offer obese adults a suitable alternative to traditional uninterrupted exercise (Jakicic et al., 1999). This is important, given that a perceived lack of time remains the top reason that sedentary overweight individuals report for not participating in regular activity.
31.5 The model The model depicted in Figure 31.2 has been developed by the authors to summarize physical activity motivation and health behavior change models – e.g., the expectancy–value model (Eccles, 1983); self-determination theory (Deci and Ryan, 1985); social cognitive theory (Bandura, 1997); the social-ecological model (Bronfenbrenner, 1977); and theory of planned behavior (Ajzen and Madden, 1986) – as well as empirical evidence demonstrating direct and mediating relationships as outlined. This non-linear model describes the individual, social and environmental factors that influence physical activity in overweight individuals. Positive changes, as a result of physical activity
Weight status Antecedents Self-perceptions, attitudes, beliefs
Physical environment
Social context
Physical activity Moderators -diet -sedentary behavior
Psychoemotional
Physical/ biological Outcomes
Figure 31.2 Model relating weight status and physical activity.
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31.5 The model
intervention, have also impacted these factors; hence the feedback loop depicted in the model (Kahn et al., 2002; Gallagher et al., 2006). The outcomes of physical activity are classified as having psycho-emotional, social and physical underpinnings.
31.5.1 Environmental factors The relationship between weight status and physical activity levels may be explained in part by environmental factors. For example, neighborhood features, such as lower perceptions of safety and characteristics that preclude walking, have been linked to higher body weight. Neighborhoods with higher walkability indices (grid-like structures with less cul-de-sacs and more street connectivity and intersections, the presence of sidewalks, and perceptions of safety) tend to promote physical activity and support a greater number of active transportation than low-walkability neighborhoods (Gordon-Larsen et al., 2006; Smith et al., 2008; Spence et al., 2008). There is a lower prevalence of overweight in these safe and walkable neighborhoods, which tend to be located in more urban living areas (Joens-Matre et al., 2008). Notwithstanding the walkability index, there is also lower prevalence of overweight in urban compared to rural areas. Furthermore, access to facilities and opportunities can be a barrier to increased physical activity levels for overweight individuals (Gallagher et al., 2006; Holt et al., 2008). Strategies to increase safe play spaces and to provide specific sports and physical activity programs to overweight youth appear to be effective in reducing weight and enhancing health and well-being (Farley et al., 2007; Weintraub et al., 2008). Greater (or increased awareness of) opportunities for physical activity among overweight individuals are necessary. One approach may be to promote lifestyle physical activity. Integrating 30–60 minutes, 5–7 days per week, of lifestyle physical activity has adaptive physical and
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psychological outcomes, including reduced anxiety and depression, increased self-esteem, and reduced fatigue (Andersen et al., 1999). Environmental manipulations, such as simple signs and visual prompts encouraging physical activity (for example, taking the stairs instead of the elevator), appear to be beneficial in increasing lifestyle physical activity (Andersen et al., 1998b; Rees, 2007). Other environmental attributes include the development and implementation of institutional policies, and community-level program development. Physical activity opportunities that enable overweight individuals to exercise together may also be particularly important.
31.5.2 Self-perceptions, attitudes and beliefs Understanding the individual-level factors that are linked to physical activity participation among overweight/obese individuals is challenging and overwhelming. Nonetheless, most emphasis has been placed on self-perceptions such as self-concept, self-efficacy, perceptions of competence, enjoyment, intrinsic motivation and interest in physical activity, and perceived barriers and drawbacks of exercising. Specifically, individuals who have weaker perceptions of the physical self and higher weight concerns are more likely to use physical activity as weight management (Page and Fox, 1997). Self-esteem tends to be directly associated with physical activity levels (Dunn et al., 2001), and overweight individuals may be more likely to report lower self-esteem than their healthyweight counterparts (Pesa et al., 2000). Perceptions of competence/physical activity self-efficacy and/or beliefs of enjoyment and interest have shown some of the strongest associations to behavior both in theory (Bandura, 1997; Eccles and Wigfield, 2002) and in empirical evidence (Deci and Ryan, 1985; van der Horst et al., 2007; Sabiston and Crocker, 2008). Unfortunately, overweight persons report lower
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perceptions of competence and generally feel less pleasure while exercising, and thus exhibit lower enjoyment beliefs (Garcia-Bengoechea et al., 2010). Once physically active, overweight individuals have reported empowering increases in perceptions of competence and self-concept that foster increased physical activity participation and greater confidence to try new activities (Gallagher et al., 2006; Sabiston et al., 2009). This relationship is illustrated in Figure 31.2 by the circular nature of the model. Research from the Australian Longitudinal Study on Women’s Health reports that depressive symptoms are higher among women who are overweight or obese as well as among more sedentary individuals (Ball et al., 2008). Physical activity can promote and maintain mental health by protecting individuals from depression and anxiety (Paffenberger et al., 1994; Motl et al., 2004). Physical activity may also be used as a treatment for non-clinical depressive symptoms and diagnosed depression (North et al., 1990; Craft and Landers, 1998). Overweight individuals face unique socialcontext barriers, such as stereotypes, embarrassment, body-image concerns, time barriers and lack of motivation, and obstacles (e.g., weather, access, support) are commonly reported (Godin et al., 1986; Gallagher et al., 2006). Efforts aimed at reducing the perception and/or existence of these barriers for overweight individuals are necessary. Simply engaging in structured physical activity programs seems to reduce the extent of reported barriers (Gallagher et al., 2006), thus providing some justification for the circular nature of the model.
31.5.3 Social context The social context includes others’ beliefs and behaviors regarding physical activity and weight status. Most individuals need to perceive strong social-normative beliefs about exercising in order to engage in the behavior. Drawing
from the sport and exercise literature, social support primarily consists of the network of providers (who) as well as the types of strategies provided (what) (Rees, 2007). For example, having physically active friends, co-workers and family members who can act as role models has a positive impact on physical activity levels for youth and adults, independent of weight status (Sallis et al., 2000). In fact, overweight youth reported that a barrier to their activity levels was not having someone with whom to engage in physical activities (Zabinski et al., 2003). The functions of social support are important factors in promoting physical activity throughout the lifespan for overweight individuals (Trost et al., 2003, Sabiston et al., 2009). Providers of physical activity-related support may provide information (i.e., advice, suggestions and guidance), emotional strategies such as encouragement and praise, esteem functions (i.e., comfort, concern, and care), and tangible support, which includes providing instrumental and practical assistance (such as gym memberships, equipment, etc.). Socially-created barriers, such as stereotypes that overweight individuals are lazy and unmotivated, and weight discrimination/fat biases may act as barriers to physical activity among overweight individuals (Ball et al., 2000; Zabinski et al., 2003; Davison et al., 2008). Furthermore, overweight individuals who internalize these stereotypes themselves are at risk of poor psychosocial functioning and wellbeing (Davison et al., 2008). Overweight girls and women report embarrassment and body image as additional factors hindering their engagement in physical activity (Hooper and Veneziano, 1995; Treasure et al., 1998; Zabinski et al., 2003). Taken together, social support and a strong social-normative belief can promote physical activity, whereas stereotypes and fat stigmatiz ation may act as deterrents to activity among overweight individuals. In addition to the direct effect that social factors may have on physical
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31.7 Outcomes
activity, they also indirectly influence behavior by affecting an individual’s self-perceptions, attitudes and beliefs about exercise (Brustad, 1996). Taken together, the factors outlined in the model are strong correlates of physical activity behavior. The following outlines ways to support overweight individuals in overcoming barriers to being physically active, and in turn increase the likelihood of engaging in physical activity.1 1. Since changing the physical environment is difficult and costly, it is important to help overweight individuals become aware of available opportunities and reframe their conception of environmental factors. An intention implementation plan has been demonstrated to be very efficient in overcoming barriers. Individuals write down barriers that they encounter or anticipate encountering in their neighborhood, and prepare a plan for what they will do when this barrier is encountered. It usually reads as follows: “If... [barrier], then... [plan]”. 2. Using visual cues and prompts to remind individuals to exercise is also an effective
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strategy. The key is to use personal photos and affirmations, rather than unrealistic magazine photos or impersonal slogans. 3. Seeking social support and using available resources, whether a trainer in a gym, an Internet website, or a colleague or friend, has been found to be helpful. Another strategy is identifying exercise partners. 4. Highlighting the positive emotions that result from exercise, rather than those of guilt, shame and embarrassment that keep individuals from being physically active, can also help overcome barriers. 5. Finally, it is crucial to help individuals set SMART (Specific, Measureable, Attainable, Realistic, and Time-based) goals.
31.5.4 Outcomes Physical activity confers physical, mental (psychological and emotional) and social health benefits (World Health Organization, 2009). The physical benefits of exercise include (but are not limited to) the reduced risk of cardiovascular disease, ischemic stroke, diabetes, various
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In order for healthcare providers to help overweight patients adopt more active lifestyles, it is always helpful to know how much physical activity they are currently engaging in. Direct measures of physical activity tend to be the most accurate, since they do not rely on patient recall. While unpractical for most clinical settings, the best technique to measure physical activity remains the water technique (i.e., the individual consumes a stable isotope to examine hydrogen and carbon utilization over a period of time to calculate total energy expenditure). A more practical approach may be to use motion sensors (i.e., accelerometers and pedometers). The accelerometers can measure activity in two or three different planes, using sensors that can reflect speed and intensity of effort. They are more costly (approximately US $350) than pedometers, and are often used more commonly in research settings. In contrast, pedometers are available in most sporting goods stores and essentially measure the number of steps taken per day. Approximating the individual’s stride length and multiplying this value by the number of steps taken will calculate daily walking distance. Good quality devices can be purchased for about US $30, and they have been found to provide motivation to patients. Patients should be encouraged to wear a pedometer for a week to get a baseline activity assessment. They should then strive to increase their daily step count by 1000 steps per day each week until they reach 10,000 steps per day. Finally, questionnaires have also been used to assess physical activity. Several valid and reliable questionnaires are available for use in a written format or administered by a trained clinician. As with all self-report questionnaires, an inability to recall past physical activity episodes can lead to problems of inaccuracy and lack of precision.
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types of cancers, and osteoporosis (Ford and Mokdad, 2008). Men and women who are physically active also have a 20–35 percent reduced relative risk of death (Macera and Powell, 2001; Hu et al., 2004; Myers et al., 2004). Moreover, physical activity leads to improved body composition (i.e., reduction in adiposity and weight control), which in turn further improves the already mentioned physical health outcomes (Tremblay et al., 1990; Warburton et al., 2006).
31.5.5 Psycho-emotional outcomes As stated above, overweight individuals often have poorer psychological profiles than their healthy-weight counterparts and chronically ill individuals (Ball et al., 2008). Physical activity benefits are often most effective for those individuals who have the worst mentalhealth profiles – providing justification for the enhanced need to help overweight individuals become more physically active. Additionally, increases in physical activity may be protective against depressive symptoms (Fox, 2000). In addition to alleviating mental health problems such as depression and anxiety, physical activity also appears to influence stress levels. Research has shown that physically active individuals are more likely to have dampened stress reactions in general. If they experience stressful events, their stress levels tend to return to baseline faster than those of individuals who are not physically active (Buckworth and Dishman, 2002; Boutcher et al., 2009). Physical activity can also be a coping mechanism used to deal with stress. Since overweight individuals tend to have lower levels of self-esteem, greater bodyimage disturbance and overall heightened selfpresentation issues, physical activity can also confer positive effects on these body-related affects and cognitions (Treasure et al., 1998). Specifically, when weight loss or perceptions of increased aerobic capacity and muscular strength are reported as a result of physical activity participation,
individuals tend to have increases in perceptions of physical self-concept. This association is depicted by the feedback loop in the model. Furthermore, with the identity shift that may be experienced as a result of regular physical activity participation, there may be the opportunity for overweight individuals to experience psychological growth. Whereas the concept of positive psychological growth has been studied in populations who have suffered trauma (i.e., cancer, death, abuse) (Tedeschi and Calhoun, 2004), it can be speculated that overweight individuals who lose weight and/or become physically active also experience this growth. The concept suggests that as overweight individuals struggle with their weight and attempt to become physically active, changes to their physical self-concept and perceptions (i.e., feelings of being more muscular, having more energy and endurance, and reduced weight) will lead to psychological growth (Tedeschi and Calhoun, 2004). This means realizing new possibilities, developing personal strength and empower ment, a new appreciation for life, and new or stronger relationships with others (Tedeschi and Calhoun, 2004). More research is needed to better understand the experiences of psychological growth for overweight individuals.
31.5.6 Social outcomes The idea of developing new or stronger relationships with others through exercise is the final outcome of the model. Generally, individuals appear to benefit most from group-based interventions as compared to individual, home-based programs or information/education efforts (van der Horst et al., 2007). Regardless of the nature of physical activity, be it groups or individual participation, the behavior appears to enhance social normative beliefs, and provide individuals with greater support networks and the ability to seek social support when needed. Moreover, when accomplished in groups, it enhances connectedness among participants (Kayman et al., 1990).
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31.6 Fit or fat It is well known that excess weight and physical inactivity are independently related to mortality. However, many public health scientists have argued that it is important to consider fitness and levels of physical activity when evaluating the health risks of obesity. A recent report examined the association between physical activity and overweight status to evaluate whether activity can reduce the adverse impact of a higher BMI on coronary heart disease (CHD) (Weinstein et al., 2008). Women were classified as active if they met public health guidelines and engaged in 30 minutes or more of moderate activity most days of the week, including brisk walking or jogging. Women who engaged in less were classified as inactive. After adjusting for confounding variables, inactive normal-weight women had a slightly (8 percent) higher risk of CHD than those who were fit and active. Conversely, the risk of developing CHD was 54 percent more likely among overweight women and 88 percent more likely for obese women compared to their normal-weight active counterparts. The data show that overweight and obese women can considerably alter the risk of heart disease by remaining physically active. This is particularly important for those obese individuals who may not be ready to lose weight. However, an active lifestyle did not entirely eliminate the risks of obesity, which reinforces the importance of active living combined with maintaining a healthy body weight.
31.7 Conclusion In conclusion, the obesity epidemic is now one of the greatest public health challenges facing healthcare professionals in developed countries around the globe. In addition to sensible meal planning, it is critical to examine strategies
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to encourage both youth and adult patients to adopt more active lifestyles and reduce sedentary activities. Accumulating appropriate amounts of activity may help to promote healthier living, even if weight status is not changed.
References Ajzen, I., & Madden, T. J. (1986). Prediction of goal-directed behavior: Attitudes, intentions, and perceived behavioral control. Journal of Experimental Social Psychology, 22, 453–474. Andersen, R. E. (1999). Exercise, an active lifestyle, and obesity: Making the exercise prescription work. Physician Sports Medicine, 27, 41–50. Andersen, R. E., Crespo, C. J., Bartlett, S. J., Cheskin, L. J., & Pratt, M. (1998a). Relationship of physical activity and television watching habits among US children with body weight and level of fatness: Results from the third national health and nutrition examination survey. Journal of the American Medical Association, 279, 938–942. Andersen, R. E., Franckowiak, S. C., Snyder, J., Bartlett, S. J., & Fontaine, K. R. (1998b). Can inexpensive signs encourage the use of stairs? Results from a community intervention. Annals of Internal Medicine, 129, 363–369. Andersen, R. E., Wadden, T. A., Bartlett, S. J., Zemel, B., Verde, T. J., & Franckowiak, S. C. (1999). Effects of lifestyle activity vs structured aerobic exercise in obese women. Journal of the American Medical Association, 281, 335–340. Andersen, R. E., Franckowiak, S. C., Zuzak, K. B., Cummings, E. S., Bartlett, S. J., & Crespo, C. J. (2006). Effects of a culturally sensitive sign on the use of stairs in African American commuters. Sozial- und Praventivmedizin, 51, 373–380. Ball, K., Crawford, D., & Owen, N. (2000). Too fat to exercise? Obesity as a barrier to physical activity. Australian and New Zealand Journal of Public Health, 24, 331–333. Ball, K., Burton, N. W., & Brown, W. J. (2008). A prospective study of overweight, physical activity, and depressive symptoms in young women. Obesity, 17, 66–71. Bandura, A. (1997). Self-efficacy: The exercise of control. New York, NY: Freeman. Boutcher, S. H., Nugent, F. W., McLaren, P. F., & Weltman, A. L. (2009). Heart period variability of trained and untrained men at rest and during mental challenges. Psychophysiology, 35, 16–22. Bronfenbrenner, U. (1977). Toward an experimental ecology of human development. The American Psychologist, 32, 513–531. Brustad, R. J. (1996). Attraction to physical activity in urban schoolchildren: Parental socialization and gender influences. Research Quarterly for Exercise and Sport, 67, 316–323.
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400
31. Physical Activity and obesity
Buckworth, J., & Dishman, R. K. (2002). Stress. In J. Buckworth & R. K. Dishman (Eds.), Exercise psychology (pp. 75–89). Champaign, IL: Human Kinetics. Craft, L. L., & Landers, D. M. (1998). The effect of exercise on clinical depression and depression resulting from mental illness: A meta-analysis. Journal of Sport & Exercise Psychology, 20, 339–357. Crespo, C. J., Andersen, R. E., Pratt, M., Snelling, A. M., & Franckowiak, S. (1998). Obesity and its relation to physical activity and television watching among US children. Medicine and Science in Sports and Exercise, 30(Suppl. 5), S80. Davison, K. K., Schmalz, D. L., Young, L. M., & Birch, L. L. (2008). Overweight girls who internalize fat stereotypes report low psychosocial well-being. Obesity, 16, S30–S38. Deci, E. L., & Ryan, R. M. (1985). Intrinsic motivation and selfdetermination in human behavior. New York, NY: Plenum. Department of Health and Human Services and US Department of Agriculture. (2005). Dietary Guidelines for Americans. Online. Available: http://healthierus.gov/ dietaryguidelines/. Dunn, A. L., Madhukar, T., & O’Neil, H. A. (2001). Physical activity dose-response effects on outcomes of depression and anxiety. Medicine & Science in Sports & Exercise, 33, S587–S597. Eccles, J. S. (1983). Expectancies, values, and academic behavior. In J. T. Spence (Ed.), Achievement and achievement motives (pp. 75–146). San Francisco, CA: W. H. Freeman. Eccles, J. S., & Wigfield, A. (2002). Motivational beliefs, values, and goals. Annual Review of Psychology, 53, 109–132. Epstein, L. H., Saelens, B. E., Myers, M. D., & Vito, D. (1997). Effects of decreasing sedentary behaviors on activity choice in obese children. Health Psychology, 16, 107–113. Farley, T. A., Meriwether, R. A., Baker, E. T., Watkins, L. T., Johnson, C. C., & Webber, L. S. (2007). Safe play spaces to promote physical activity in inner-city children: Results form a pilot study of an environmental intervention. American Journal of Public Health, 97, 1625–1631. Floriani, V., & Kennedy, C. (2007). Promotion of physical activity in primary care for obesity treatment/prevention in children. Current Opinion in Pediatrics, 19(1), 99–103. Floriani, V., & Kennedy, C. (2008). Promotion of physical activity in children. Current Opinion in Pediatrics, 20(1), 90–95. Ford, E. S., & Mokdad, A. H. (2008). Epidemiology of obesity in the Western Hemisphere. The Journal of Clinical Endocrinology and Metabolism, 93, S1–S8. Fox, K. R. (2000). The effects of exercise on self-perceptions and self-esteem. In S. Biddle, K. R. Fox, & S. Boutcher (Eds.), Physical activity and psychological well-being (pp. 88–117). New York, NY: Routledge. Gallagher, K. I., Jakicic, J. M., Napolitano, M. A., & Marcus, B. (2006). Psychosocial factors related to physical activity and weight loss in overweight women. Medicine and Science in Sports and Exercise, 38, 971–980.
Garcia-Bengoechea, E., Sabiston, C. M., Ahmed, R., & Faroush, M. (2010). Exploring links to unorganized and organized physical activity during adolescence: the role of gender, socioeconomic status, weight status and enjoyment of physical education. Research Quarterly in Exercise and Sport, 81, 7–16. Godin, G., Shepard, R. J., & Golantonio, A. (1986). The cognitive profile of those who intend to exercise but do not. Public Health Reports, 101, 521–526. Gordon-Larsen, P., Nelson, M. C., Page, P., & Popkin, B. M. (2006). Inequality in the built environment underlies key health disparities in physical activity and obesity. Pediatrics, 117, 417–424. Hagan, R. D., Upton, S. J., Wong, L., & Whittam, J. (1986). The effects of aerobic conditioning and/or caloric restriction in overweight men and women. Medicine and Science in Sports and Exercise, 18, 87–94. Haskell, W. L., Blair, S. N., & Hill, J. O. (2009). Physical activity: Health outcomes and importance for public health policy. Preventive Medicine, 49(4), 280–282. Holt, N. L., Moylan, B. A., Spence, J. C., Lenk, J. M., Sehn, Z. L., & Ball, G. D. C. (2008). Treatment preferences of overweight youth and their parents in Western Canada. Qualitative Health Research, 18, 1206–1219. Hooper, J., & Veneziano, L. (1995). Distinguishing starters from non-starters in an employee physical activity inventive program. Health Education Quarterly, 22, 49–60. Hu, F. B., Willett, W. C., Li, T., Stampfer, M. J., Colditz, G. A., & Manson, J. E. (2004). Adiposity compared with physical activity in predicting mortality among women. New England Journal of Medicine, 351, 2694–2703. Institute of Medicine. (2002). Dietary reference intakes for energy, carbohydrates, fiber, fat, protein and amino acids (macronutrients). Washington, DC: National Academies Press. Jakicic, J. M., Winters, C., Lang, W., & Wing, R. R. (1999). Effects of intermittent exercise and use of home exercise equipment on adherence, weight loss, and fitness in overweight women: A randomized trial. Journal of the American Medical Association, 282, 1554–1560. Jakicic, J. M., Clark, K., Coleman, E., Donnelly, J. E., Foreyt, J., Melanson, E., Volek, J., & Volpe, S. L. (2001). American college of sports medicine position stand. Appropriate intervention strategies for weight loss and prevention of weight regain for adults. Medicine and Science in Sports and Exercise, 33, 2145–2156. Joens-Matre, R. R., Welk, G. J., Calabro, M. A., Russell, D. W., Nicklay, E., & Hensley, L. D. (2008). Rural–urban differences in physical activity, physical fitness, and overweight prevalence of children. The Journal of Rural Health, 24, 49–54. Kahn, E. B., Ramsey, L. T., Brownson, R. C., Heath, G. W., Howze, E. H., Powell, K. E., Stone, E. J., Rajab, M. W., & Corso, P. (2002). The effectiveness of interventions to
1. From Brain to Behavior
references
increase physical activity: A systematic review. American Journal of Preventive Medicine, 22, 73–107. Kayman, S., Bruvold, W., & Stern, J. S. (1990). Maintenance and relapse after weight loss in women: Behavioral aspects. The American Journal of Clinical Nutrition, 52, 800–807. Klem, M. L., Wing, R. R., McGuire, M. T., Seagle, H. M., & Hill, J. O. (1997). A descriptive study of individuals successful at long-term maintenance of substantial weight loss. The American Journal of Clinical Nutrition, 66, 239–246. Macera, J., & Powell, K. E. (2001). Population attributable risk: Implications of physical activity dose. Medicine and Science in Sport and Exercise, 33, S635–S639. Motl, R. W., Birnbaum, A. S., Kubik, M. Y., & Dishman, R. K. (2004). Naturally occurring changes in physical activity are inversely related to depressive symptoms during early adolescence. Psychosomatic Medicine, 66, 336–342. Myers, K., Kaykha, A., Gergor, S., Abella, J., Zaheer, N., Lear, S., Yamazaki, T., & Froelicher, V. (2004). Fitness versus physical activity patterns in predicting mortality in men. American Journal of Medicine, 117, 912–918. North, T. C., McCullagh, P., & Tran, Z. V. (1990). Effect of exercise on depression. Exercise and Sport Sciences Reviews, 18, 379–415. Ogden, C. K., Carroll, M. D., Curtin, L. R., McDowell, M. A., Tabak, C. J., & Flegal, K. M. (2006). Prevalence of overweight and obesity in the United States, 1999–2004. Journal of the American Medical Association, 295(13), 1549–1555. Paffenberger, R. S., Lee, I. M., & Leung, R. (1994). Physical activity and personal characteristics associated with depression and suicide in American college men. Acta Psychiatrica Scandinavica, S377, 16–22. Page, A., & Fox, K. R. (1997). Adolescent weight management and the physical self. In K. R. Fox (Ed.), The physical self: From motivation to well-being (pp. 229–256). Champaign, IL: Human Kinetics. Pesa, J. A., Syre, T. R., & Jones, E. (2000). Psychosocial differences associated with body weight among female adolescents: The importance of body image. Journal of Adolescent Health, 26, 330–337. Physical Activity Guidelines Advisory Committee. (2008). Physical activity guidelines advisory committee report, 2008. Washington, DC: US Department of Health and Human Services. Rees, T. (2007). Influence of social support on athletes. In S. Jowett & D. Lavallee (Eds.), Social psychology in sport (pp. 223–231). Champaign, IL: Human Kinetics. Sabiston, C. M., & Crocker, P. R. E. (2008). Exploring selfperceptions ad social influences as correlates of adolescent leisure-time physical activity. Journal of Sport & Exercise Psychology, 30, 3–22. Sabiston, C. M., McDonough, M. H., Sedgwick, W. A., & Crocker, P. R. (2009). Muscle gains and emotional strains: conflicting experiences of change among overweight
401
women participating in an excercise intervention program. Qualitative Health Research, 19, 466–480. Sallis, J. F., Prochaska, J. J., & Taylor, W. C. (2000). A review of correlates of physical activity of children and adolescents. Medicine and Science in Sport and Exercise, 32, 963–975. Saris, W. H., Blair, S. N., van Baak, M. A., Eaton, S. B., Davies, P. S., Di Pietro, L., et al. (2003). How much physical activity is enough to prevent unhealthy weight gain? Outcome of the IASO 1st Stock Conference and consensus statement. Obesity Reviews, 4, 101–114. Schoeller, D. A. (1999). Recent advances from application of doubly labeled water to measurement of human energy expenditure. The Journal of Nutrition, 129, 1765–1768. Shields, M., & Tremblay, M. S. (2008). Sedentary behaviour and obesity. Health Reports, 19, 19–30. Smith, K., Brown, B., Yamada, I., Kowaleski-Jones, L., Zick, C., & Fan, J. (2008). Walkability and body mass index: density, design, and new diversity measures. American Journal of Preventive Medicine, 35, 237–244. Spence, J. C., Cutumisu, N., Edwards, J., & Evans, J. (2008). Influence of neighbourhood design and access to facilities on overweight and obesity among preschool children. International Journal of Pediatric Obesity, 3, 109–116. Tedeschi, R. G., & Calhoun, L. G. (2004). Posttraumatic growth: Conceptual foundations and empirical evidence. Psychological Inquiry, 15, 1–18. Treasure, D. C., Lox, C. L., & Lawton, B. R. (1998). Determinants of physical activity in a sedentary, obese female population. Journal of Sport & Exercise Psychology, 20, 218–224. Tremblay, A., Despres, J. P., Leblanc, C., Craig, C. L., Ferris, B., Stephens, T., & Bouchard, C. (1990). Effect of intensity of physical activity on body fatness and fat distribution. American Journal of Clinical Nutrition, 51, 153–157. Trost, S. G., Sirard, J., Dowda, M., Pfeiffer, K. A., & Pate, R. R. (2003). Physical activity in overweight and non overweight preschool children. International Journal of Obesity and Related Metabolic Disorders, 27, 834–839. van der Horst, K., Paw, M. J., Twisk, J. W. R., & Mechelen, W. (2007). A brief review on correlates of physical activity and sedentariness in youth. Medicine & Science in Sports and Exercise, 39, 1241–1250. Warburton, D. E. R., Whitney Nicol, C., & Bredin, S. D. (2006). Health benefits of physical activity: The evidence. Journal of the American Medical Association, 174, 801–809. Weinstein, A. R., Sesso, H. D., Lee, I. M., Rexrode, K. M., Cook, N. R., Manson, J. E., et al. (2008). The joint effects of physical activity and body mass index on coronary heart disease risk in women. Archives of Internal Medicine, 168, 884–890. Weintraub, D. L., Tirumalai, E. C., Haydel, F., Fujimoto, M., Fulton, J. E., & Robinson, T. N. (2008). The Stanford sports to prevent obesity randomized trial (SPORT). Archives of Pediatric Adolescent Medicine, 162, 232–237.
1. From Brain to Behavior
402
31. Physical Activity and obesity
Wing, R. R. (1999). Physical activity in the treatment of adulthood overweight and obesity: Current evidence and research issues. Medicine & Science in Sports & Exercise, 31, S547–S552. World Health Organization. (2009). Global strategy on diet, physical activity and health. Geneva: WHO.
Zabinski, M. F., Saelens, B. E., Stein, R. I., Hayden-Wade, H. A., & Wilfley, D. E. (2003). Overweight children’s barriers to and support for physical activity. Obesity Research, 11, 238–246.
1. From Brain to Behavior