Andrea L. Dunn

Physical activity dose-response effects on outcomes of depression and anxiety

PURPOSE The purpose of this study was to examine the scientific evidence for a dose-response relation of physical activity with depressive and anxiety disorders. METHODS Computer database searches of MEDLINE, PsychLit, and Internet and personal retrieval systems to locate population studies, randomized controlled trials (RCTs), observational studies, and consensus panel judgments were conducted. RESULTS Observational studies demonstrate that greater amounts of occupational and leisure time physical activity are generally associated with reduced symptoms of depression. Quasi-experimental studies show that light-, moderate-, and vigorous-intensity exercise can reduce symptoms of depression. However, no RCTs have varied frequency or duration of exercise and controlled for total energy expenditure in studies of depression or anxiety. Quasi-experimental and RCTs demonstrate that both resistance training and aerobic exercise can reduce symptoms of depression. Finally, the relation of exercise dose to changes in cardiorespiratory fitness is equivocal with some studies showing that fitness is associated with reduction of symptoms and others that have demonstrated reduction in symptoms without increases in fitness. CONCLUSION All evidence for dose-response effects of physical activity and exercise come from B and C levels of evidence. There is little evidence for dose-response effects, though this is largely because of a lack of studies rather than a lack of evidence. A dose-response relation does, however, remain plausible.

Lifestyle physical activity interventions: History, short- and long-term effects, and recommendations

INTRODUCTION Lifestyle physical activity interventions have resulted in response to the public health problem of promoting regular amounts of physical activity to the majority of U.S. adults who remain inadequately or completely inactive. These lifestyle interventions allow a person to individualize his/her physical activity programs to include a wide variety of activities that are at least of moderate intensity and to accumulate bouts of these activities in a manner befitting his/her life circumstances. METHODS We reviewed the history of lifestyle physical activity interventions and defined lifestyle physical activity based on this review. We located 14 studies that met this definition. RESULTS Lifestyle physical activity interventions are effective at increasing and maintaining levels of physical activity that meet or exceed public health guidelines for physical activity in representative samples of previously sedentary adults and obese children. The majority of these interventions have been delivered by face-to-face contact in small groups, which limits their public health impact. However, a small number of studies demonstrate that these interventions can be delivered by mail and telephone, which may enhance their generalizability. Most of these studies utilized behavior change theories such as Social Cognitive Theory, the Transtheoretical Model, and Behavior Learning to shape the interventions. Lifestyle interventions aimed at modifying the environment, such as signs posted to increase stair climbing, also have been shown to be effective over the short term. CONCLUSIONS The major issues concerning lifestyle physical activity interventions are: (1) testing their ability to be implemented on a large scale; (2) examining cost-effectiveness for different modes of delivery; and (3) researching the efficacy in populations such as the elderly, minorities, economically disadvantaged, and individuals with concurrent disease. More studies aimed at manipulating the environment to increase physical activity need to be tested over periods of one year or longer. It is possible that lifestyle interventions could be integrated and delivered by new technologies such as interactive computer-mediated programs, telephone, or computer web-based formats. All of these recommended approaches should utilize valid and reliable measures of physical activity and should examine the health effects, particularly on a longitudinal basis. Basic dose-response studies in controlled settings also are needed to help us understand the health effects of accumulated moderate intensity activity.

Psychosocial mediators of physical activity behavior among adults and children

BACKGROUND Researchers examining theory-based, physical activity (PA) interventions postulate that interventions are effective by changing theoretical constructs hypothesized to mediate the relationship between the intervention and PA behavior. Research indicates that PA interventions are effective for increasing PA behavior. However, whether effective interventions are due to predicted changes in theoretical constructs remains poorly understood. METHODS Studies that examined theoretical constructs (i.e., mediators) in PA interventions of adults or children, which used experimental designs and met other criteria for evaluating mediation, were collected via literature searches, personal searches of files, and personal communications. Only studies examining the direct effect of the intervention on the hypothesized mediator were considered relevant for this study. RESULTS Based on our criteria, the adult literature search yielded ten studies and the child literature search yielded two studies. The most common mediators examined included behavioral processes of change, cognitive processes of change, self-efficacy, decisional balance, social support, and enjoyment. Research indicates that behavioral processes are likely mediators. There was some support for the importance of self-efficacy as a mediator. CONCLUSIONS Few studies have used statistically recommended methods to examine mediators in PA intervention studies. Therefore, definitive conclusions about the importance of the mediators reviewed are not possible at this time. Additional PA mediator-intervention studies using recommended statistical methods are necessary to truly test if theory-based PA interventions are effective due to predicted changes in theoretical constructs.

Exploring the effect of the environment on physical activity: A study examining walking to work

BACKGROUND Research on physical activity and the physical environment is at the correlates stage, so it is premature to attribute causal effects. This paper provides a conceptual approach to understanding how the physical design of neighborhoods may influence behavior by disentangling the potential effects of income, university education, poverty, and degree of urbanization on the relationship between walking to work and neighborhood design characteristics. METHODS The study merges Canadian data from 27 neighborhood observations with information on walking to work from the 1996 census. Hierarchical linear modeling was used to create a latent environment score based on 18 neighborhood characteristics (e.g., variety of destinations, visual aesthetics, and traffic). The relationship between the environment score and walking to work was modeled at the second level, controlling for income, university education, poverty, and degree of urbanization. RESULTS With the exceptions of visual interest and aesthetics, each neighborhood characteristic contributed significantly to the environment score. The environment score was positively associated with walking to work, both with and without adjustment for degree of urbanization. Controlling for university education, income, and poverty did not influence these relationships. CONCLUSIONS The positive association between the environment score and walking to work, controlling for degree of urbanization supports the current movement toward the development of integrated communities for housing, shops, workplaces, schools, and public spaces. Given the need for research to guide environmental interventions, collaboration among public health practitioners, urban planners, and transportation researchers is essential to integrate knowledge across sectors.

Obesity Among Those with Mental Disorders: A National Institute of Mental Health Meeting Report

The National Institute of Mental Health convened a meeting in October 2005 to review the literature on obesity, nutrition, and physical activity among those with mental disorders. The findings of this meeting and subsequent update of the literature review are summarized here. Levels of obesity are higher in those with schizophrenia and depression, as is mortality from obesity-related conditions such as coronary heart disease. Medication side effects, particularly the metabolic side effects of antipsychotic medications, contribute to the high levels of obesity in those with schizophrenia, but increased obesity and visceral adiposity have been found in some but not all samples of drug-naïve patients as well. Many of the weight-management strategies used in the general population may be applicable to those with mental disorders, but little is known about the effects of these strategies on this patient population or how these strategies may need to be adapted for the unique needs of those with mental disorders. The minimal research on weight-management programs for those with mental disorders indicates that meaningful changes in dietary intake and physical activity are possible. Physical activity is an important component of any weight-management program, particularly for those with depression, for which a substantial body of research indicates both mental and physical health benefits. Obesity among those with mental disorders has not received adequate research attention, and empirically-based interventions to address the increasing prevalence of obesity and risk of cardiovascular and metabolic diseases in this population are lacking.

Cost-Effectiveness of Lifestyle and Structured Exercise Interventions in Sedentary Adults: Results of Project ACTIVE

BACKGROUND Project ACTIVE was a randomized clinical trial comparing two physical activity interventions, lifestyle and traditional structured exercise. The two interventions were evaluated and compared in terms of cost effectiveness and ability to enhance physical activity among sedentary adults. DESIGN This was a randomized clinical trial. SETTING/ PARTICIPANTS The study included 235 sedentary but healthy community-dwelling adults. INTERVENTION A center-based lifestyle intervention that consisted of behavioral skills training was compared to a structured exercise intervention that included supervised, center-based exercise. MAIN OUTCOME MEASURES The main outcome measures of interest included cost, cardiorespiratory fitness, and physical activity. RESULTS Both interventions were effective in increasing physical activity and fitness. At 6 months, the costs of the lifestyle and structured interventions were, respectively,

Correlates of satisfaction with body function and body appearance in middle- and older aged adults: The activity counseling trial (ACT)

46.53 and

Six-month physical activity and fitness changes in Project Active, a randomized trial

190.24 per participant per month. At 24 months these costs were

Brain norepinephrine and metabolites after treadmill training and wheel running in rats.

17.15 and

Active for Life : Final Results from the Translation of Two Physical Activity Programs

49.31 per participant per month. At both 6 months and 24 months, the lifestyle intervention was more cost-effective than the structured intervention for most outcomes measures. CONCLUSIONS A behaviorally-based lifestyle intervention approach in which participants are taught behavioral skills to increase their physical activity by integrating moderate-intensity physical activity into their daily lives is more cost-effective than a structured exercise program in improving physical activity and cardiorespiratory health. This study represents one of the first attempts to compare the efficiency of intervention alternatives for improving physical activity among healthy, sedentary adults.