***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Purpose . To examine the effect of a mail-mediated intervention , based on self-determination theory , on adults ' exercise behavior .  Methods . The study was a r and omized control trial conducted over a 2-month period . Of the initial 185 volunteer participants , 126 ( 68.1 % ) completed question naires at baseline , 1 month , and 2 months . Participants in intervention-only and intervention-plus-booster groups received a mail-delivered packet containing strategies design ed to promote perceptions of autonomy , competence , and relatedness regarding exercise . Those in a control group received an American Heart Association physical-activity facts packet . After 1 month , those in the intervention-plus-booster group received a booster postcard , reiterating the main points of the initial intervention packet .  Exercise behavior was the primary outcome variable . Perceptions of autonomy , competence , and relatedness were evaluated as mediating variables . Results . Separate 3 ( group ) × 3 ( time ) repeated measures analyses of variance conducted for men and women revealed that for women , all three groups significantly increased exercise levels over the 2-month period . No significant interactions were found regarding the influence of the intervention on the mediating variables . A process evaluation indicated a lack of compliance regarding completing intervention-packet worksheets . Discussion . Findings suggested that more intensive interventions and greater fidelity of treatment may be needed to evidence change in exercise behavior Background Research on the motivational model proposed by Self-Determination Theory ( SDT ) provides theoretically sound insights into reasons why people adopt and maintain exercise and other health behaviors , and allows for a meaningful analysis of the motivational processes involved in behavioral self-regulation . Although obesity is notoriously difficult to reverse and its recidivism is high , adopting and maintaining a physically active lifestyle is arguably the most effective strategy to counteract it in the long-term . The purpose s of this study are twofold : i ) to describe a 3-year r and omized controlled trial ( RCT ) aim ed at testing a novel obesity treatment program based on SDT , and ii ) to present the rationale behind SDT 's utility in facilitating and explaining health behavior change , especially physical activity/exercise , during obesity treatment . Methods Study design , recruitment , inclusion criteria , measurements , and a detailed description of the intervention ( general format , goals for the participants , intervention curriculum , and main SDT strategies ) are presented . The intervention consists of a 1-year group behavioral program  for overweight and moderately obese women , aged 25 to 50 ( and pre-menopausal ) , recruited from the community at large through media advertisement . Participants in the intervention group meet weekly or bi-weekly with a multidisciplinary intervention team ( 30 2 h sessions in total ) , and go through a program covering most topics considered critical for successful  weight control .  These topics and especially their delivery were adapted to comply with SDT and Motivational Interviewing guidelines . Comparison group receive a general health education curriculum . After the program , all subjects are follow-up for a period of 2 years . Discussion Results from this RCT will contribute to a better underst and ing of how motivational characteristics , particularly those related to physical activity/exercise behavioral self-regulation , influence treatment success , while exploring the utility of Self-Determination Theory for promoting health behavior change in the context of obesity . Trial Registration Clinical Trials Gov. Identifier This study was set out to test if autonomous motivation mediated the relationship between self-efficacy and 12-month physical activity ( PA )  in adults with type 2 diabetes involved in a r and omized exercise trial . Participants ( n = 234 ) completed question naires measuring  barrier self-efficacy at 3 months , autonomous motivation at 6 months , and  PA  at 12 months . A mediational analysis of longitudinal data revealed that autonomous motivation mediated the relationship between barrier-self-efficacy and PA .  High barrier self-efficacy can therefore help predict 12-month PA  in adults with type 2 diabetes , although this effect is attenuated by autonomous motivation . Hence , participating in PA for autonomous reasons such as by choice and /or for fun further explains  PA  at 12 months in this population . Results of this study extend our underst and ing of the motivational constructs involved in  PA  in the maintenance phase . This study has important theoretical implication s in that it helps to organize and consoli date well-known correlates of  PA  by proposing a temporal relationship between them that could be tailored in interventions PURPOSE This study evaluated exercise-related predictors of  successful long-term weight control in women by analyzing the extent to which sustained exercise participation and self-determination theory (SDT)-based exercise motivation variables mediated the impact of a behavioral weight control intervention on 3-yr weight change . METHODS Longitudinal r and omized controlled trial consisting of a 1-yr SDT-based intervention and a 2-yr follow-up with 221 female participants ( means ± SD : age = 37.6 ± 7 yr , body mass index = 31.6 ± 4.1 kg·m(-2 ) ) . The tested model incorporated experimentally manipulated perceived need support , motivational regulations , and 2-yr exercise adherence as mediators of the intervention 's impact on 3-yr weight change . Paths were tested using partial least squares analysis . Where there were significant intervening paths , tests of mediation were conducted . RESULTS Treatment had significant effects on 1- and 2-yr autonomous regulations , 2-yr physical activity , and 3-yr weight change , fully mediated by the tested paths ( effect ratio = 0.10 - 0.61 ) . Moderate and vigorous exercise at 2 yr had a significant effect ( P < 0.001 ) on weight loss success at 3 yr and partially mediated the effect of treatment on weight change . The 2-yr autonomous regulation effects on follow-up weight change were only partially mediated by physical activity ( effect ratio = 0.42 ) . CONCLUSIONS This application of SDT to physical activity and weight management showed that not all types of motivation predict long-term behavioral outcomes and that sustained moderate and vigorous exercise mediated long-term weight change . It provides strong evidence for a link between experimentally increased autonomous motivation and exercise and long-term weight loss maintenance . Results highlight the importance of interventions targeting the internalization of exercise behavioral regulation and making exercise and physical activity positive and meaningful experiences rather than simply focusing on immediate behavior change in overweight/obese women Background The National Institute of Clinical Excellence in the UK has recommended that the effectiveness of ongoing exercise referral schemes to promote physical activity should be examined in research trials . Recent empirical evidence in health care and physical activity promotion context s provides a foundation for testing the utility of a Self Determination Theory (SDT)-based exercise referral consultation . Methods / Design Design : An exploratory cluster r and omised controlled trial comparing st and ard provision exercise on prescription with a Self Determination Theory-based ( SDT ) exercise on prescription intervention . Participants : 347 people referred to the Birmingham Exercise on Prescription scheme between November 2007 and July 2008 . The 13 exercise on prescription sites in Birmingham were r and omised to current practice ( n = 7 ) or to the SDT-based intervention ( n = 6 ) . Outcomes measured at 3 and 6-months : Minutes of moderate or vigorous physical activity per week assessed using the 7-day Physical Activity Recall ; physical health : blood pressure and weight ; health status measured using the Dartmouth CO-OP charts ; anxiety and depression measured by the Hospital Anxiety and Depression Scale and vitality measured by the subjective vitality score ; motivation and processes of change : perceptions of autonomy support from the advisor , satisfaction of the needs for competence , autonomy , and relatedness via physical activity , and motivational regulations for exercise . Discussion This trial will determine whether an exercise referral programme based on Self Determination Theory increases physical activity and other health outcomes compared to a st and ard programme and will test the underlying SDT-based process model ( perceived autonomy support , need satisfaction , motivation regulations , outcomes ) via structural equation modelling . Trial registration The trial is registered as Current Controlled trials IS RCT N07682833 BACKGROUND Regular physical activity can help to prevent cardiovascular disease in women . Underst and ing midlife women 's exercise goals could offer insight into their motivational facilitators and barriers , and assist in the development of better primary prevention strategies for this population . OBJECTIVES We sought to investigate the relationship between midlife women 's  physical activity goals and their physical activity participation over time . METHODS A r and om sample of healthy , midlife women ( 40 - 60 years of age ) was selected to participate in a longitudinal study ( n = 156 ) . This study fit a linear mixed model to the data to investigate the fixed effects of physical activity goals on physical activity participation , controlling for Body Mass Index ( BMI ) and Social Support . Mediational analyses were conducted to investigate whether commitment and planning mediated these results . RESULTS There were significant differences between participants with distinct types of goals on physical activity participation over time ( i.e. , baseline , 1 month , and 1 year postbaseline ) , controlling for the effects of BMI and Social Support . Participants with Weight Loss and Health Benefits goals participated in significantly less physical activity than those with Sense of Well-being and Stress Reduction goals . Commitment and Planning each mediated the relationship between participant goals and their physical activity participation . CONCLUSIONS These data suggest having physical activity goals that aim to decrease weight or benefit health may not bode well for healthy midlife women who desire to sustain physically active lives . Instead , health care providers and health promotion specialists might better facilitate long-term participation among healthy women if they emphasize physical activity as a means to enhance their quality of life Assessment of habitual physical activity in epidemiologic and health education studies has been difficult . A seven-day physical activity recall interview was developed and administered in a community health survey , a r and omized clinical trial , and two worksite health promotion programs during 1979 - 1982 . These studies were conducted in several population s in California , Texas , Pennsylvania , and New Jersey . Energy expenditure estimates from the physical activity recall conformed to expected age- and sex-specific values in the cross-sectional community survey . Estimates of energy expenditure were also congruent with other questions on physical activity and job classification . In a r and omized , one-year exercise trial , the physical activity recall detected increases in energy expenditure in the treated group and was positively associated with miles run during training ( p less than 0.05 ) . Changes in energy expenditure were associated with changes in maximal oxygen uptake ( VO2max ( r = 0.33 , p less than 0.05 ) and body fatness ( r = -0.50 , p less than 0.01 ) at six months , and in high density lipoprotein-cholesterol ( r = 0.31 , p less than 0.05 ) and triglyceride ( r = -0.41 , p less than 0.01 ) at one year . The physical activity recall detected significant ( p less than 0.01 ) increases in energy expenditure in treatment groups in two worksite health promotion projects . These data suggest that the physical activity recall provides useful estimates of habitual physical activity for research in epidemiologic and health education studies The purpose of this study was to propose and test a motivational model of high school dropout .  The model posits that teachers , parents , and the school administration 's behaviors towards students influence students ' perceptions of competence and autonomy . The less autonomy supportive the social agents ' behaviors are , the less positive the students ' perceptions of competence and autonomy . In turn , the less positive students ' perceptions are , the lower their level of self-determined school motivation are . Finally , low levels of self-determined motivation lead students to develop intentions to drop out of high school , which are later implemented , leading to actual dropout behavior . This model was tested with high school students ( N = 4,537 ) by means of a prospect i ve design . Results from analyses of variance and a structural equation modeling analysis ( with LISREL ) were found to support the model for all participants and for each gender separately The assertion that both the content of goals and the motives behind goals affect psychological well-being has been controversial . Three studies examined this issue directly , showing that both what goals people pursue ( i.e. , whether they strive for extrinsic vs. intrinsic goal contents ) and why people pursue them ( i.e. , whether they strive for autonomous vs. controlled motives ) make significant independent contributions to psychological well-being . The pattern emerged in between-person and within-person studies of cross-sectional well-being and also emerged in a year-long study of prospect i ve change in well-being . Implication s for prescriptive theories of happiness are discussed OBJECTIVE Using self-determination theory ( SDT ) , we examined relationships between  cardiac rehabilitation ( CR ) participants ' perceived autonomy support , motivation for exercise , and exercise behavior . RESEARCH METHOD / DESIGN Male CR out patients ( N = 53 ; M age = 62.83 + /- 10.78 years ) . The design was correlational ( cross-sectional and prospect i ve ) , examining relationships between perceived autonomy support  and  motivation for exercise at Week 4 of CR participation as well as motivation and  CR attendance and other indicators of exercise behavior ( frequency , duration , total exercise time ) at a 1-week follow-up , 10 weeks later . RESULTS Perceived autonomy support was correlated with self-determined motivation , r(53 ) = .32 , p < .05 . Self-determined motivation predicted total exercise volume at follow-up , r(53 ) = .34 , p < .05 , as well as length of exercise session duration ( R(2 ) = .27 ; beta = .52 , p < .001 ) . CONCLUSION Results support SDT and the potential for autonomy support from interventionists to affect self-determined motivation and exercise behavior of participants involved in CR Aims : We examined whether autonomy supportive and self-efficacy 
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Results The results show consistent support for a positive relation between more autonomous forms of motivation and exercise , with a trend towards identified regulation predicting initial/short-term adoption more strongly than intrinsic motivation , and intrinsic motivation being more predictive of long-term exercise adherence .
The literature is also consistent in that competence satisfaction and more intrinsic motives positively predict exercise participation across a range of sample s and setting s. Mixed evidence was found concerning the role of other types of motives ( e.g. , health/fitness and body-related ) , and also the specific nature and consequences of introjected regulation .
The majority of studies have employed descriptive ( i.e. , non-experimental ) design s but similar results are found across cross-sectional , prospect i ve , and experimental design s. Conclusion Overall , the literature provides good evidence for the value of SDT in underst and ing exercise behavior , demonstrating the importance of autonomous ( identified and intrinsic ) regulations in fostering physical activity .
Nevertheless , there remain some inconsistencies and mixed evidence with regard to the relations between specific SDT constructs and exercise .