Action control of exercise behavior: evaluation of social cognition, cross-behavioral regulation, and automaticity

Intention is considered the proximal determinant of behavior in many popular theories applied to understanding physical activity, yet intention-behavior discordance is high. Thus, an understanding of constructs that facilitate or inhibit the successful translation of intentions into behavior is both timely and important. The action control approach of dividing the intention-behavior relationship into quadrants of successful/unsuccessful intenders has shown utility in the past by demonstrating the magnitude of intention-behavior discordance and allowing for an outcome variable to test predictors. The purpose of this article was to evaluate automaticity and cross-behavioral regulation as predictors of exercise action control, in conjunction with other more standard social cognitive predictors of perceived behavioral control and affective and instrumental attitudes. Participants were a random sample of 263 college students who completed predictor measures at time one, followed by exercise behavior two weeks later. Participants were classified into three intention-behavior profiles: (1) nonintenders (14.1%; n = 31), (2) unsuccessful intenders (35.5%; n = 78), and (3) successful intenders (48.6%; n = 107). Affective attitude, perceived behavioral control, automaticity, and cross-behavioral regulation were predictors of action control. The results demonstrate that automaticity and cross-behavioral regulation, constructs not typically used in intention-based theories, predict intention-behavior discordance.

A model-based approach to select case sites for walkability audits

Walkability audits provide valuable information about pedestrian environments, but are time-consuming and can be expensive to implement. In this paper, we propose a model-based approach to select sites for conducting walkability audits. The key idea is to estimate a model of travel behavior at the meso-scale level, which can be examined to identify locations where the behavior is under- and over-estimated. We conjecture that systematic under- and over-estimation can be caused by micro-level factors that influence the behavior. The results can be used to identify sites for walkability audits. The approach is demonstrated with a case study in Hamilton, Canada. A model of walk shares forms the basis of the site selection procedure. After identifying areas with higher and lower shares than predicted by the model we select a sample of neighborhoods for audits. Analysis of the results reveals elements of the local environment that associate with greater-than-expected walk shares. The case study demonstrates that the proposed model-based strategy can be used to better target limited resources, and produce valuable insights into micro-level factors that affect travel behavior.

Daily physical activity in young children and their parents: A descriptive study

BACKGROUND

Little is known about physical activity (PA) in young children and about the relationship between their PA and that of their parents.

OBJECTIVE

The main purpose of the present study (Y-Be-Active) was to examine the daily PA levels of young children and their parents, and to explore the relationship between children's and parents' PA.

METHOD

Fifty-four children (mean age 4.3 years) and their parents (54 mothers, mean age 35.8 years; 50 fathers, mean age 38.2 years) wore accelerometers for three weekdays and two weekend days. Parents also completed questionnaires on family sociodemographics and PA habits.

RESULTS

Children spent most of their time in light PA. Almost all children attained 30 min of daily moderate-to-vigorous PA (MVPA), and most boys and girls attained 60 min of daily MVPA on weekdays. Only 60% of fathers and approximately one-half of mothers attained 30 min of daily MVPA on weekdays and weekend days. Children's and fathers' PA were correlated on weekends. Few parents (20% to 30%) participated regularly in organised PA with their child. Fathers' involvement in PA with their children was associated with higher MVPA in children.

CONCLUSIONS

Many young children and parents did not meet current Canadian recommendations for daily PA. Parental involvement in PA with their young children, particularly the involvement of fathers, appeared to promote higher levels of MVPA in young children.

BACKGROUND

Little is known about physical activity (PA) in young children and about the relationship between their PA and that of their parents.

OBJECTIVE

The main purpose of the present study (Y-Be-Active) was to examine the daily PA levels of young children and their parents, and to explore the relationship between children’s and parents’ PA.

METHOD

Fifty-four children (mean age 4.3 years) and their parents (54 mothers, mean age 35.8 years; 50 fathers, mean age 38.2 years) wore accelerometers for three weekdays and two weekend days. Parents also completed questionnaires on family sociodemographics and PA habits.

RESULTS

Children spent most of their time in light PA. Almost all children attained 30 min of daily moderate-to-vigorous PA (MVPA), and most boys and girls attained 60 min of daily MVPA on weekdays. Only 60% of fathers and approximately one-half of mothers attained 30 min of daily MVPA on weekdays and weekend days. Children’s and fathers’ PA were correlated on weekends. Few parents (20% to 30%) participated regularly in organised PA with their child. Fathers’ involvement in PA with their children was associated with higher MVPA in children.

CONCLUSIONS

Many young children and parents did not meet current Canadian recommendations for daily PA. Parental involvement in PA with their young children, particularly the involvement of fathers, appeared to promote higher levels of MVPA in young children.

[A critical analysis of physical activity recommendations in Spain]

OBJECTIVE

To identify official documents with recommendations on physical activity published by the autonomous regions of Spain with the goal of evaluating their compliance with the physical activity recommendations of the World Health Organization (WHO).

METHODS

We conducted a content analysis of 55 documents of the ministries of health of several regional governments containing recommendations on physical activity.

RESULTS

Eighty-four percent of the autonomous regions in Spain made recommendations on aerobic physical activity and 37% made recommendations on strength training. However, the number of documents consistent with the WHO criteria was as follows: aerobic activity (n=11, 58%), adults (n=10, 53%), the elderly (n=5, 26%), children/adolescents (n=1, 5%); strength training, adults (n=6, 32%), the elderly (n=3, 16%), children/adolescents (n=1, 5%); balance (n=5, 26%); at least 10minutes continuous physical activity (n=6, 32%); recommendation of up to 300minutes per week (n=10, 53%); intensity of physical activity (n=2, 11%).

CONCLUSIONS

The recommendations of the autonomous regions tend to focus on aerobic physical activity and to under-represent strength training. Moreover, only one autonomous region conforms to the WHO recommendations for physical activity. The regions with higher rates of population aging and a higher percentage of children and adolescents fail to make recommendations on physical activity consistent with the WHO guidelines.

Time displacement and confidence to participate in physical activity

BACKGROUND

Time spent on sedentary behaviors is often blamed for low physical activity rates, but tests of time displacement are limited.

PURPOSE

The purpose of this study was to examine time-graded assessments of self-efficacy to engage in physical activity compared to either high- or low-ranked sedentary leisure behaviors among a workplace sample. Several demographic factors were examined as moderators of time displacement.

METHODS

Participants were a worksite sample of 2,009 men and women who completed measures of demographics, physical activity, and self-efficacy after performing a thought listing procedure to generate their most-/least-preferred sedentary leisure-time behaviors.

RESULTS

Repeated measures analysis of variance across four gradients of available leisure-time (20, 30, 60, 120 min) showed some evidence of displacement (20 min less confident than 120 min) when considering their most preferred sedentary behavior but not their least preferred. These results, however, were moderated by age, occupational work hours, free time, education, and physical activity status.

CONCLUSION

Targeted interventions for young professionals with high work hours and limited physical activity experience seem prudent in order to improve their self-efficacy to achieve regular physical activity through sedentary behavior control.

Measurement of human energy expenditure, with particular reference to field studies: an historical perspective

Over the years, techniques for the study of human movement have ranged in complexity and precision from direct observation of the subject through activity diaries, questionnaires, and recordings of body movement, to the measurement of physiological responses, studies of metabolism and indirect and direct calorimetry. This article reviews developments in each of these domains. Particular reference is made to their impact upon the continuing search for valid field estimates of activity patterns and energy expenditures, as required by the applied physiologist, ergonomist, sports scientist, nutritionist and epidemiologist. Early observers sought to improve productivity in demanding employment. Direct observation and filming of workers were supplemented by monitoring of heart rates, ventilation and oxygen consumption. Such methods still find application in ergonomics and sport, but many investigators are now interested in relationships between habitual physical activity and chronic disease. Even sophisticated questionnaires still do not provide valid information on the absolute energy expenditures associated with good health. Emphasis has thus shifted to use of sophisticated pedometer/accelerometers, sometimes combining their output with GPS and other data. Some modern pedometer/accelerometers perform well in the laboratory, but show substantial systematic errors relative to laboratory reference criteria such as the metabolism of doubly labeled water when assessing the varied activities of daily life. The challenge remains to develop activity monitors that are sufficiently inexpensive for field use, yet meet required accuracy standards. Possibly, measurements of oxygen consumption by portable respirometers may soon satisfy part of this need, although a need for valid longer term monitoring will remain.

The pleasure and displeasure people feel when they exercise at different intensities: decennial update and progress towards a tripartite rationale for exercise intensity prescription

The public health problem of physical inactivity has proven resistant to research efforts aimed at elucidating its causes and interventions designed to alter its course. Thus, in most industrialized countries, the majority of the population is physically inactive or inadequately active. Most theoretical models of exercise behaviour assume that the decision to engage in exercise is based on cognitive factors (e.g. weighing pros and cons, appraising personal capabilities, evaluating sources of support). Another, still-under-appreciated, possibility is that these decisions are influenced by affective variables, such as whether previous exercise experiences were associated with pleasure or displeasure. This review examines 33 articles published from 1999 to 2009 on the relationship between exercise intensity and affective responses. Unlike 31 studies that were published until 1998 and were examined in a 1999 review, these more recent studies have provided evidence of a relation between the intensity of exercise and affective responses. Pleasure is reduced mainly above the ventilatory or lactate threshold or the onset of blood lactate accumulation. There are pleasant changes at sub-threshold intensities for most individuals, large inter-individual variability close to the ventilatory or lactate threshold and homogeneously negative changes at supra-threshold intensities. When the intensity is self-selected, rather than imposed, it appears to foster greater tolerance to higher intensity levels. The evidence of a dose-response relation between exercise intensity and affect sets the stage for a reconsideration of the rationale behind current guidelines for exercise intensity prescription. Besides effectiveness and safety, it is becoming increasingly clear that the guidelines should take into account whether a certain level of exercise intensity would be likely to cause increases or decreases in pleasure.

Physical activity for health: What kind? How much? How intense? On top of what?

Physical activity improves health. Different types of activity promote different types of physiologic changes and different health outcomes. A curvilinear reduction in risk occurs for a variety of diseases and conditions across volume of activity, with the steepest gradient at the lowest end of the activity scale. Some activity is better than none, and more is better than some. Even light-intensity activity appears to provide benefit and is preferable to sitting still. When increasing physical activity toward a desired level, small and well-spaced increments will reduce the incidence of adverse events and improve adherence. Prior research on the relationship between activity and health has focused on the value of moderate to vigorous activity on top of an indefinite and shifting baseline. Given emerging evidence that light activities have health benefits and with advances in tools for measuring activities of all intensities, it may be time to shift to zero activity as the conceptual starting point for study.

Evidence-based risk assessment and recommendations for physical activity clearance: established cardiovascular disease1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process

Physical activity is an effective lifestyle therapy for patients at risk for, or with, documented cardiovascular disease (CVD). Current screening tools — the Physical Activity Readiness Questionnaire (PAR-Q) and the Physical Activity Readiness Medical Evaluation (PARmed-X) — require updating to align with risk/benefit evidence. We provide evidence-based recommendations to identify individuals with CVD at lower risk, intermediate risk, or higher risk of adverse events when participating in physical activity. Forms of exercise and the settings that will appropriately manage the risks are identified. A computer-assisted search of electronic databases, using search terms for CVD and physical activity risks and benefits, was employed. The Appraisal of Guidelines for Research and Evaluation were applied to assess the evidence and assign a strength of evidence rating. A strength rating for the physical activity participation clearance recommendation was assigned on the basis of the evidence. Recommendations for physical activity clearance were made for specific CVD groups. Evidence indicates that those who are medically stable, who are involved with physical activity, and who have adequate physical ability can participate in physical activity of lower to moderate risk. Patients at higher risk can exercise in medically supervised programs. Systematic evaluation of evidence indicates that clinically stable individuals with CVD may participate in physical activity with little risk of adverse events. Therefore, changes in the PAR-Q should be undertaken and a process of assessment and consultation to replace the PARmed-X should be developed. Patients at lower risk may exercise at low to moderate intensities with minimal supervision. Those at intermediate risk should exercise with guidance from a qualified exercise professional. Patients at higher risk should exercise in medically supervised programs.

Evidence-based risk assessment and recommendations for exercise testing and physical activity clearance in apparently healthy individuals1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process

Increased physical activity (PA) is associated with improved health and quality of life in the general population. A dose–response effect is evident between increasing levels of PA participation and a lower relative risk for cardiovascular disease and all-cause mortality. However, there is also clear evidence that PA acutely increases the risk of an adverse cardiovascular (CV) event and sudden cardiac death (SCD) significantly above levels expected at rest. Adverse CV events during PA may be triggered acutely by the physiological stress of exercise. This investigation will review the available literature describing the CV risks of exercise testing and PA participation in apparently healthy individuals. A systematic review of the literature was performed using electronic databases, including Medline, CINAHL, SPORT discus, EMBASE, Cochrane DSR, ACP Journal Club, and DARE; additional relevant articles were hand-picked and the final grouping was used for the review using the AGREE process to assess the impact and quality of the selected articles. Six hundred and sixteen relevant articles were reviewed with 51 being identified as describing adverse CV events during exercise and PA. Data suggests the risks of fatal and nonfatal events during maximal exercise testing in apparently healthy individuals rarely occur (approximately <0.8 per 10 000 tests or 1 per 10 000 h of testing). The incidence of adverse CV events is extremely low during PA of varying types and intensities, with data limited almost exclusively to fatal CV events, as nonfatal events are rarely reported. However, this risk is reduced by 25%–50% in those individuals who have prior experience with increased levels of PA, particularly vigorous PA. Throughout a wide age range, the risk of SCD and nonfatal events during PA remain extremely low (well below 0.01 per 10 000 participant hours), but both increasing age and PA intensity are associated with greater risk. In most cases of exercise-related SCD, undetected pre-existing disease is present and SCD is typically the first clinical event. The risks of an adverse CV event during exercise testing and PA are rare and are outweighed by the health benefits. Given this risk-benefit relationship, the PAR-Q is an appropriate method to identify those at higher risk across a wide age span and should be used in conjunction with appropriate clinical guidelines for guiding individuals towards graduated PA. There are not adequate data to describe the risks of PA in those individuals considered to be at higher risk but without cardiovascular disease.

Trends and changes in research on the psychology of physical activity across 20 years: a quantitative analysis of 10 journals

OBJECTIVE

To investigate content of the psychology of physical activity research over the past 20 years.

METHOD

Volumes of 10 journals, identified by impact factor and relevance to physical activity were audited every other year, during the period of 1990-2008. Inclusion criteria were studies that measured a physical activity outcome, and/or a psychological outcome as a result of physical activity. Data were extracted and coded based on 15 factors.

RESULTS

The review yielded 889 studies for analysis. Total volume of studies (from 127 in the 1990s to 762 in the 2000s), and the proportionate content space allotted to journals has increased significantly across 20 years (effect size w=0.24) (Cohen, 1992). Many study characteristics (assessment of minority/high-risk groups, self-report measurement, cross-sectional designs) have not changed. There was evidence, however, of less growth in research among older adults and young children (effect size w=0.15) compared to other age groups (effect size w=0.24), a move from pure measurement studies (effect size w=0.21) to descriptive research (effect size w=0.27), and considerable growth in environmental correlates research across time (effect size w=0.41) in the 10 journals sampled.

CONCLUSION

The behavioral science of physical activity has clearly increased in prominence and volume among the 10 journals sampled, but methodological characteristics of research could be improved in the future.

Enhancing the effectiveness of clearance for physical activity participation: background and overall process1This paper is one of a selection of papers published in the Special Issue entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal's usual peer-review process

Recent feedback from physical activity (PA) participants, fitness professionals, and physicians has indicated that there are limitations to the utility and effectiveness of the existing PAR-Q and PARmed-X screening tools for PA participation. The aim of this study was to have authorities in exercise and chronic disease management to work with an expert panel to increase the effectiveness of clearance for PA participation using an evidence-based consensus approach and the well-established Appraisal of Guidelines for Research and Evaluation (AGREE) Instrument. Systematic reviews were conducted to develop a new PA clearance protocol involving risk stratification and a decision-tree process. Evidence-based support was sought for enabling qualified exercise professionals to have a direct role in the PA participation clearance process. The PAR-Q+ was developed to use formalized probes to clarify problematic responses and to explore issues arising from currently diagnosed chronic disease or condition. The original PARmed-X tool is replaced with an interactive computer program (ePARmed-X+) to clear prospective PA participants for either unrestricted or supervised PA or to direct them to obtain medical clearance. Evidence-based validation was also provided for the direct role of highly qualified university-educated exercise professionals in the PA clearance process. The risks associated with exercise during pregnancy were also evaluated. The systematic review and consensus process, conforming to the AGREE Instrument, has provided a sound evidence base for enhanced effectiveness of the clearance process for PA participation of both asymptomatic populations and persons with chronic diseases or conditions.

Evidence-based risk assessment and recommendations for physical activity clearance: pregnancy1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process

Recommendations for physical activity during pregnancy have progressed significantly in the last 30 years and continue to evolve as an increasing body of scientific evidence becomes available. In addition, there is an increasing number of women who wish to either maintain physical fitness levels during the prenatal period or initiate exercise for a healthier lifestyle during pregnancy. As such, consistent evaluation of the risks associated with exercise during pregnancy is warranted for maternal and fetal well-being. The primary purpose of this systematic review was to evaluate the scientific information available regarding maternal and fetal responses as it relates to the occurrence of adverse exercise-related events in pregnant women without contraindications to exercise. A systematic and evidence-based approach was used to analyze critically the level of evidence for risks associated with acute and chronic exercise during pregnancy in healthy pregnant women. All articles were screened according to standardized evaluation criteria developed by a panel of experts. A total of 74 investigations that involved 3766 pregnant women were included in the analysis. Of the 74 studies, only 35 studies documented the presence or absence of adverse events. The serious adverse event rate for these studies was 1.4 per 10 000 h of exercise. The adverse event rate increased to 6.8 per 10 000 h of exercise when including the occurrence of more mild events and exercise-related fetal bradycardia and tachycardia. Previously inactive or active women (without contraindications) are at a low risk for adverse fetal or maternal events if they participate in routine physical activity during pregnancy.

Governmental interventions and youth physical activity in France

Data from a representative sample of 2474 French youth show that, despite a 7-year French Ministry of Health strategy for nutrition and physical activities, adolescents' motivation to practise sports and physical activities decreased significantly between 2001 and 2008. While this paper focuses on the context of physical activity in France, the general discussion may be applicable to other countries concerned with the obesity pandemic.

New Canadian Physical Activity Guidelines

The Canadian Society for Exercise Physiology (CSEP), in cooperation with ParticipACTION and other stakeholders, and with support from the Public Health Agency of Canada (PHAC), has developed the new Canadian Physical Activity Guidelines for Children (aged 5–11 years), Youth (aged 12–17 years), Adults (aged 18–64 years), and Older Adults (aged ≥65 years). The new guidelines include a preamble to provide context and specific guidelines for each age group. The entire guideline development process was guided by the Appraisal of Guidelines for Research Evaluation (AGREE) II instrument, which is the international standard for clinical practice guideline development. Thus, the guidelines have gone through a rigorous and transparent developmental process; we based the recommendations herein on evidence from 3 systematic reviews, and the final guidelines benefitted from an extensive online and in-person consultation process with hundreds of stakeholders and key informants, both domestic and international. Since 2006, the products of our efforts resulted in the completion of 21 peer-reviewed journal articles (including 5 systematic reviews) that collectively guided this work. The process that Canadian researchers undertook to update the national physical activity guidelines represents the most current synthesis, interpretation, and application of the scientific evidence to date.

Nouvelles Directives canadiennes en matière d’activité physique

La Société canadienne de physiologie de l’exercice (SCPE) en collaboration avec ParticipACTION et des parties prenantes et avec l’appui de l’Agence de santé publique du Canada (ASPC) a élaboré de nouvelles Directives canadiennes en matière d’activité physique à l’intention des enfants (âgés de 5 à 11 ans), des jeunes (âgés de 12 à 17 ans), des adultes (âgés de 18 à 64 ans) et des aînés (âgés de 65 ans et plus). Les nouvelles directives sont composées d’un préambule situant le contexte et de directives spécifiques à chaque tranche d’âge. L’élaboration complète des directives a respecté la Grille II d’évaluation de la qualité des recommandations pour la pratique clinique (AGREE), un outil reconnu internationalement pour l’élaboration des lignes directrices en pratique clinique. L’élaboration des directives résulte d’un processus rigoureux et transparent. Les recommandations présentées dans cet article sont basées sur les données probantes relevées dans trois analyses documentaires systématiques, et les directives finales ont bénéficié des fruits d’une vaste consultation en ligne et en personne auprès de centaines d’intervenants concernés et de sources de premier plan, sur la scène nationale et internationale. Depuis 2006, les résultats de nos efforts se retrouvent entre autres dans 21 articles (dont 5 analyses documentaires systématiques) sanctionnés par des pairs. La démarche entreprise par les chercheurs canadiens pour la mise à jour des directives en matière d’activité physique a abouti à la synthèse, l’interprétation et l’application des données probantes les plus récentes à ce jour.

Are youth BMI and physical activity associated with better or worse than expected health-related quality of life in adulthood? The Physical Activity Longitudinal Study

PURPOSE

Body mass index (BMI) and physical activity (PA) affect health-related quality of life (HRQL); however, the long-term impact of youth BMI and PA on adult HRQL is unknown. We investigated the relationship of youth BMI and PA to adult HRQL 22 years later.

METHODS

Subjects included 310 participants aged 7 to 18 in the 1981 Canada Fitness Survey, followed up in 2002-2004. The associations of youth BMI and leisure time PA to adult HRQL were examined, comparing to age- and sex-adjusted Canadian SF-36 norms.

RESULTS

Bivariate analyses revealed positive associations between youth overweight and mental aspects of adult HRQL, but little association with physical aspects. In logistic regression adjusting for adult BMI and other covariates, overweight youth were 7 times more likely than healthy weight youth to score at/above the norm on both mental health (MH) and bodily pain, and almost 18 times more likely on the mental component score (MCS). Youth BMI was also positively associated with general health (GH), social functioning, and role emotional. Removing adult BMI from the models led to attenuated associations with mental HRQL and no association with GH. Longitudinal BMI status change was explored, and findings supported the main regression results. Youth PA was not associated with adult HRQL.

CONCLUSIONS

Youth overweight conveyed a long-term positive impact on several aspects of adult HRQL, and this impact may be both direct and indirect through BMI change and the effect on adult BMI. Youth PA had no long-term impact on adult HRQL.

Predicting the effect of interactive video bikes on exercise adherence: An efficacy trial

Exercise games that employ video game technology are increasing in the marketplace but have received scant research attention despite their popularity. The purpose of this study was to evaluate the effect of videobike gaming on the constructs of the theory of planned behavior (TPB) and adherence in comparison to a cycling condition where participants listen to self-selected music. Participants were 29 inactive young men assigned randomly to experimental (n = 16) or comparison (n = 13) conditions. The recommended training regime consisted of moderate intensity activity (60-75% heart rate reserve), 3 days/week for 30 min/day for 6 weeks. At the end of the first session, participants were asked to complete TPB measures and these were subsequently measured 6 weeks later. Attendance was used as the measure of adherence. Results showed that affective attitude and adherence across the 6 weeks significantly favored the videobike condition over the comparison condition. Regression analyses suggested partial mediation of the effect of the videobike condition on adherence via affective attitude. This is the first study to provide evidence that interactive videobikes may improve adherence over traditional cycling because the activity produces higher affective attitudes. The results are promising for expanding to community-based evaluation.

Physical activity and functional limitations in older adults: a systematic review related to Canada's Physical Activity Guidelines

BACKGROUND

The purpose was to conduct systematic reviews of the relationship between physical activity of healthy community-dwelling older (>65 years) adults and outcomes of functional limitations, disability, or loss of independence.

METHODS

Prospective cohort studies with an outcome related to functional independence or to cognitive function were searched, as well as exercise training interventions that reported a functional outcome. Electronic database search strategies were used to identify citations which were screened (title and abstract) for inclusion. Included articles were reviewed to complete standardized data extraction tables, and assess study quality. An established system of assessing the level and grade of evidence for recommendations was employed.

RESULTS

Sixty-six studies met inclusion criteria for the relationship between physical activity and functional independence, and 34 were included with a cognitive function outcome. Greater physical activity of an aerobic nature (categorized by a variety of methods) was associated with higher functional status (expressed by a host of outcome measures) in older age. For functional independence, moderate (and high) levels of physical activity appeared effective in conferring a reduced risk (odds ratio ~0.5) of functional limitations or disability. Limitation in higher level performance outcomes was reduced (odds ratio ~0.5) with vigorous (or high) activity with an apparent dose-response of moderate through to high activity. Exercise training interventions (including aerobic and resistance) of older adults showed improvement in physiological and functional measures, and suggestion of longer-term reduction in incidence of mobility disability. A relatively high level of physical activity was related to better cognitive function and reduced risk of developing dementia; however, there were mixed results of the effects of exercise interventions on cognitive function indices.

CONCLUSIONS

There is a consistency of findings across studies and a range of outcome measures related to functional independence; regular aerobic activity and short-term exercise programmes confer a reduced risk of functional limitations and disability in older age. Although a precise characterization of a minimal or effective physical activity dose to maintain functional independence is difficult, it appears moderate to higher levels of activity are effective and there may be a threshold of at least moderate activity for significant outcomes.

Automatic and motivational correlates of physical activity: does intensity moderate the relationship?

The purpose of this study was to examine the predictive capability of a habit construct, controlling for intention and perceived behavioral control, with moderate and strenuous intensity physical activity. This approach was expanded through an examination of whether conscious deliberation in the initiation of physical activity would attenuate these findings and a test of the intention-habit interaction. Participants were 337 undergraduate students who completed the habit measure and measures of intention, deliberation, and perceived behavioral control phrased in either moderate or vigorous intensities at time 1. This was followed by a measure of behaviour 2 weeks later. Results using stacked structural equation models (moderate and vigorous intensity) demonstrated the direct effect of habit and accounted for a significant effect on physical activity after controlling for intention and perceived behavioral control; this effect was invariant to intensity and conscious deliberation. A 3-way interaction, however, was identified for the habit X intention relationship and intensity. In the moderate intensity condition, individuals who reported higher habits showed a lower intention-behavior relationship when compared with those who reported modest or low habits. By contrast, individuals who reported high habit levels in the vigorous physical activity condition demonstrated a larger intention-behavior relationship than their modest and low habit counterparts. The results support the notions that some properties of physical activity may have an automatic component and that habits may be important to physical activity action initiation.

Effect of Implementation Intentions to Change Behaviour: Moderation by Intention Stability

The aim of this study was to assess the effects of implementation intentions on leisure-time physical activity, taking into account the stability of intention. At baseline (T0), 349 participants completed a psychosocial questionnaire and were randomly assigned to implementation intention or control condition. Three months after baseline assessment (T1), participants in the experimental group were asked to plan where, when, and how they would exercise. Leisure-time physical activity was assessed 3 mo. later (i.e., at 6-mo. follow-up; T2). The intervention had no significant effect on physical activity at 6-mo. follow-up. However, a significant interaction of group and intention stability was observed, with the effect of the intervention on behaviour statistically significant only among those with unstable intention. Intention stability thus moderated the effect of the intervention, i.e., the intervention was more successful among individuals who needed support to change (unstable intenders).

Pilot study of a family physical activity planning intervention among parents and their children

Physical activity interventions among youth have resulted in modest outcomes; thus, there is a need to increase the theoretical fidelity of interventions and hone pilot work before embarking on large scale trials. The purpose of this study was to examine the effect of a planning intervention in comparison to a standard condition on intergenerational physical activity in families with young children. Inactive families (N = 85) were randomized to either a standard condition (received physical activity guidelines and a local municipal healthy active living guide) or the intervention (physical activity guidelines, local municipal healthy active living guide + planning material) after completing a baseline questionnaire package. Sixty-five families (standard condition n = 34; intervention condition n = 31) completed the 4 week follow-up questionnaire package. Complete cases and intention to treat analyses showed that the planning intervention resulted in higher self-reported family physical activity compared to the standard condition and this was due to an increase in unstructured family activities over the 4 weeks. The results are promising and suggest that theoretical fidelity targeting parent regulation of family activity may be a helpful approach to increasing weekly energy expenditure.

Does physical activity intensity moderate social cognition and behavior relationships?

OBJECTIVE

Public health messaging about physical activity (PA) sometimes combines moderate and vigorous intensity, but the variance/invariance of the motives for PA by intensity has received scant attention. Thus, the purpose of this study was to examine the beliefs and motivations associated with regular moderate- and vigorous-intensity PA in a college sample using the framework of Ajzen's Theory of Planned Behavior (TPB).

PARTICIPANTS AND METHODS

A college sample of 337 participants was randomly assigned to complete measures of the TPB framed for either vigorous- or moderate-intensity PA and subsequently completed self-reported measures of PA 2 weeks later.

RESULTS

Mean comparisons indicated that participants held higher mean behavioral beliefs about the benefits of vigorous PA for improving appearance and fitness, but vigorous PA was perceived to take more time than moderate-intensity activities. A stacked structural equation model and follow-up Fisher z tests, however, suggested no differences between the associations of TPB constructs with intention or PA by intensity.

CONCLUSIONS

The findings provide support for the current public health approach of combining moderate and vigorous physical activity messaging through the general invariance of motives by intensity.

Physical activity and postmenopausal breast cancer: proposed biologic mechanisms and areas for future research

Convincing evidence now supports a probable preventive role for physical activity in postmenopausal breast cancer. The mechanisms by which long-term physical activity affect risk, however, remain unclear. The aims of this review were to propose a biological model whereby long-term physical activity lowers postmenopausal breast cancer risk and to highlight gaps in the epidemiologic literature. To address the second aim, we summarized epidemiologic literature on 10 proposed biomarkers, namely, body mass index (BMI), estrogens, androgens, sex hormone binding globulin, leptin, adiponectin, markers of insulin resistance, tumor necrosis factor-alpha, interleukin-6, and C-reactive protein, in relation to postmenopausal breast cancer risk and physical activity, respectively. Associations were deemed "convincing," "probable," "possible," or "hypothesized" using set criteria. Our proposed biological model illustrated the co-occurrence of overweight/obesity, insulin resistance, and chronic inflammation influencing cancer risk through interrelated mechanisms. The most convincing epidemiologic evidence supported associations between postmenopausal breast cancer risk and BMI, estrogens, and androgens, respectively. In relation to physical activity, associations were most convincing for BMI, estrone, insulin resistance, and C-reactive protein. Only BMI and estrone were convincingly (or probably) associated with both postmenopausal breast cancer risk and physical activity. There is a need for prospective cohort studies relating the proposed biomarkers to cancer risk and for long-term exercise randomized controlled trials comparing biomarker changes over time, specifically in postmenopausal women. Future etiologic studies should consider interactions among biomarkers, whereas exercise trials should explore exercise effects independently of weight loss, different exercise prescriptions, and effects on central adiposity.