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OBJECTIVES: To investigate the dissemination potential of a Tai Ji Quan-based program, previously shown to be efficacious for reducing risk of falls in older adults, through outpatient clinical settings. DESIGN: A single-group pre/post design in which participants attended a twice-weekly Tai Ji Quan training program for 24 weeks. SETTING: Communities in Lane County, Oregon. PARTICIPANTS: Independently living individuals (N = 379) aged 65 and older. MEASUREMENTS: Using the Reach, Effectiveness, Adoption, Implementation and Maintenance framework, the primary outcome was the proportion of participating healthcare providers who made referrals. Secondary outcomes were the proportion of referred individuals agreeing to participate and enrolling in the program, and measures of program implementation, maintenance, and effectiveness (on measures of falls, balance, gait, physical performance, and balance efficacy). RESULTS: Of the 252 providers invited to participate, 157 made referrals (62% adoption rate). Of 564 individuals referred, 379 (67% reach) enrolled in the program, which was successfully implemented in senior and community centers with good fidelity, 283 completed the program (75% retention), and 212 of these attended 75% or more of the 48 sessions. Participants reported a reduction in falls, with an incidence rate of 0.13 falls per person-month, and showed significant improvement from baseline in all outcome measures. A 3-month postintervention follow-up indicated encouraging levels of program maintenance among providers, participants, and community centers. CONCLUSION: Healthcare providers successfully implemented a protocol to refer individuals at risk of falling to a Tai Ji Quan-based program. The evidence-based program appears readily scalable and exportable, with potential for substantial clinical and public health effect. Language: en

Using a multilevel latent growth curve modeling (LGCM) approach, this study examined longitudinal change in levels of physical fitness performance over time (i.e. four years) in young adolescents aged from 12–13 years. The sample consisted of 6622 students from 138 secondary schools in Singapore. Initial analyses found between-school variation on fitness test scores with intra-class correlations ranging from 0.02–0.19. Subsequent multilevel growth curve analyses revealed a quadratic trend of the longitudinal data across five stations of performance tests, with significant within-school student variability in change over time. The result of the multilevel LGCM showed that there were strong school effects on all of the physical fitness performances, in addition to inter- and intra-individual differences.

Objectives. To evaluate the impact of implementing an evidence-based fall prevention intervention in community senior centers. Methods. We used a single-group design to evaluate the Tai Ji Quan: Moving for Better Balance (TJQMBB) program’s adoption, population reach, implementation, effectiveness, and maintenance among 36 senior centers in 4 Oregon counties between 2012 and 2016. The primary outcome measure, as part of the effectiveness evaluation, was number of falls as ascertained by self-report. Trained TJQMBB instructors delivered the program to community-dwelling older adults for 48 weeks, with a 6-month postintervention follow-up. Results. TJQMBB was adopted by 89% of the senior centers approached and reached 90% of the target population. The program resulted in a 49% reduction in the total number of falls and improved physical performance. Participation was well maintained after the program’s completion. The average cost-effectiveness ratio for the 48-week program implementation was $917 per fall prevented and $676 per fall prevented for multiple falls. Conclusions. TJQMBB is an effective public health program that can be broadly implemented in community senior centers for primary prevention of falls among community-dwelling older adults.

Use of structural equation modeling (SEM) methodology to study interactive relationships among latent variables began with the work of Kenny and Judd (1984) who developed a method of testing interactions involving continuous latent variables by forming products of multiple indicator variables. Until recently, there has been considerable difficulty implementing the method in SEM programs. This article reviews a single indicator approach (Joreskog & Yang, 1996) and multiple indicator approaches (Jaccard & Wan, 1995; Ping, 1996) that simplify Kenny and Judd's method. An illustrative application using an empirical example examining the interactive effect of perceptions of competence and perceptions of autonomy on exercise intrinsic motivation is presented. Practical issues surrounding the use of these different approaches are discussed.

The GET FIT (Group Exercise Training for Functional Improvement after Treatment) trial is the first randomized controlled trial to test the efficacy of two specific and separate types of exercise training, tai chi and strength training, to reduce falls in older female cancer survivors. The purpose of the present study is to: 1) report on the feasibility of recruitment into the trial and 2) report on retention and adherence to the exercise trial. Women were recruited through cancer registries, clinician referral, letters to past research participants, self-referral and screening of electronic health records (EHR). Interested and eligible women were consented and randomized to participate in a strength training, tai chi, or flexibility (placebo control) exercise class two times a week for 6 months. Out of 1490 screened women, 442 began the study intervention and 52 withdrew before the 6 month intervention was complete resulting in an 88% retention rate. Women who withdrew from the study reported more worry about falls compared to those who did not withdraw (p

Importance Falls in older adults are a serious public health problem associated with irreversible health consequences and responsible for a substantial economic burden on health care systems. However, identifying optimal choices from among evidence-based fall prevention interventions is challenging as few comparative data for effectiveness are available. Objective To determine the effectiveness of a therapeutically tailoredtai ji quanintervention,Tai Ji Quan: Moving for Better Balance (TJQMBB), developed on the classic concept oftai ji(also known as tai chi), and a multimodal exercise (MME) program relative to stretching exercise in reducing falls among older adults at high risk of falling. Design, Setting, and Participants A single-blind, 3-arm, parallel design, randomized clinical trial (February 20, 2015, to January 30, 2018), in 7 urban and suburban cities in Oregon. From 1147 community-dwelling adults 70 years or older screened for eligibility, 670 who had fallen in the preceding year or had impaired mobility consented and were enrolled. All analyses used intention-to-treat assignment. Interventions One of 3 exercise interventions: two 60-minute classes weekly for 24 weeks of TJQMBB, entailing modified forms and therapeutic movement exercises; MME, integrating balance, aerobics, strength, and flexibility activities; or stretching exercises. Main Outcomes and Measures The primary measure at 6 months was incidence of falls. Results Among 670 participants randomized, mean (SD) age was 77.7 (5.6) years, 436 (65%) were women, 617 (92.1%) were white, 31 (4.6%) were African American. During the trial, there were 152 falls (85 individuals) in the TJQMBB group, 218 (112 individuals) in the MME group, and 363 (127 individuals) in the stretching exercise group. At 6 months, the incidence rate ratio (IRR) was significantly lower in the TJQMBB (IRR, 0.42; 95% CI, 0.31-0.56;P Conclusions and Relevance Among community-dwelling older adults at high risk for falls, a therapeutically tailoredtai ji quanbalance training intervention was more effective than conventional exercise approaches for reducing the incidence of falls. Trial Registration ClinicalTrials.gov identifier:NCT02287740

Grounded in the conceptual framework of the Sport Commitment Model and previous empirical studies conducted in Western countries, this study was designed to (a) test and validate a Thai version of the Athlete Opinion Survey to assess components of the Sport Commitment Model in Thai youth athletes and (b) examine structural relationships among various constructs of the Sport Commitment Model as assessed by the Thai version of the Athlete Opinion Survey. Survey data were collected from 1,704 Thai youth athletes and analyzed via structural equation modeling methodologies to establish evidence for validity and measurement reliability. Results from various analyses indicated adequate support for the hypothesized factorial structure and acceptable reliability estimates of the Thai version of the Athlete Opinion Survey subscales. Moreover, modeling analyses showed empirical support for the hypothesized structural relationships underlying the Sport Commitment Model in the Thai youth athlete population. The findin...

Use of oocytes from prepubertal animals for in vitro embryo production holds potential application for reducing generation intervals and increasing genetic progress through embryo transfer. The objective of these studies was to compare the effect of three sperm pretreatments (prior to in vitro fertilization) and seven embryo culture protocols on fertilization rate and (or) subsequent development of in vitro fertilized embryos derived from oocytes harvested from ovaries of 1-6 month old prepubertal Boer goats in China. Cleavage rates were highest for embryos fertilized with heparin-treated versus calcium ionophore- or caffeine-treated sperm. Similar rates of blastocyst development were observed using heparin- and ionophore-treated sperm, which were higher than obtained with caffeine-treated sperm. No differences in cleavage or blastocyst rates were observed following embryo culture in basal medias (synthetic oviductal fluid (SOF), Charles Rosenkrans 1 (CR1) or tissue culture medium-199 (TCM-199)) containing 10% fetal bovine serum (FBS). Cumulus or oviductal cell co-culture did not enhance cleavage or blastocyst rates relative to culture in SOF+10% FBS. Replacement of FBS in SOF medium with 0.3% BSA increased cleavage rates, but did not increase rates of blastocyst development. Sequential culture in SOF+0.3% BSA followed by SOF+10% FBS increased blastocyst yield versus continuous culture in SOF+10% FBS and tended to increase blastocyst yield versus continuous culture in SOF+0.3% BSA. These results demonstrate a pronounced effects of sperm pretreatments and in vitro embryo culture systems on rates of blastocyst development and provide a potential protocol (sperm pretreatment with heparin and sequential embryo culture in SOF+0.3% BSA followed by SOF+10% FBS) for generation of the significant numbers of in vitro produced blastocysts from oocytes of prepubertal Boer goats necessary for application of embryo transfer in rural regions of China for distribution of Boer goat genetics.

Few studies have examined interaction effects between person and environment, especially for cardiovascular disease (CVD) risk. The purpose of this study was to examine built environment characteristics and resident health behaviors as they relate to change in blood pressure, an important component of CVD.Participants (N=1145, aged 50-75 at baseline) were recruited from 120 neighborhoods in Portland, Oregon. Using a longitudinal design, we assessed changes in participants' systolic and diastolic blood pressure from baseline to 1-year follow-up (2006-2007 to 2007-2008). Independent variables included baseline neighborhood-level measures of GIS-constructed neighborhood walkability and density of fast-food restaurants, and resident-level measures of meeting physical activity recommendations and eating fruits and vegetables.There was a small but significant resident-level increase in both systolic and diastolic blood pressure (P0.001) over the 1-year observation period. A similar trend was also observed at the neighborhood level (P0.001). Significant differences in change in blood pressure, by neighborhood walkability, were observed, with decreases in systolic and diastolic blood pressure for those living in high walkable neighborhoods (P0.001). Neighborhoods of low walkability but with a high density of fast-food outlets and residents making visits to fast-food restaurants were significantly associated with increases in blood pressure measures over time. The negative effect of fast-food restaurants on blood pressure was diminished among high-walkable neighborhoods, with benefits observed among residents meeting guidelines for physical activity and eating fruits and vegetables.Neighborhoods with high walkability may ameliorate the risk of hypertension at the community level and promotion of neighborhood walkability could play a significant role in improving population health and reducing CVD risk.

This study examined neighborhood built environment characteristics (fast-food restaurant density, walkability) and individual eating-out and physical activity behaviors in relation to 1-year change in body weight among adults 50–75 years of age at baseline. The authors surveyed 1,145 residents recruited from 120 neighborhoods in Portland, Oregon. During the 1-year follow-up (2006–2007 to 2007–2008), mean weight increased by 1.72 kg (standard deviation, 4.3) and mean waist circumference increased by 1.76 cm (standard deviation, 5.6). Multilevel analyses revealed that neighborhoods with a high density of fast-food outlets were associated with increases of 1.40 kg in weight (P < 0.05) and 2.04 cm in waist circumference (P < 0.05) among residents who visited fast-food restaurants frequently. In contrast, high-walkability neighborhoods were associated with decreases of 1.2 kg in weight (P < 0.05) and 1.57 cm in waist circumference (P < 0.05) among residents who increased their levels of vigorous physical activity during the 1-year assessment period. Findings point to the negative influences of the availability of neighborhood fast-food outlets and individual unhealthy eating behaviors that jointly affect weight gain; however, better neighborhood walkability and increased levels of physical activity are likely to be associated with maintaining a healthy weight over time.

Tai Chi—Moving for Better Balance, a falls-prevention program developed from a randomized controlled trial for community-based use, was evaluated with the RE-AIM framework in 6 community centers. The program had a 100% adoption rate and 87% reach into the target older adult population. All centers implemented the intervention with good fidelity, and participants showed significant improvements in health-related outcome measures. This evidence-based tai chi program is practical to disseminate and can be effectively implemented and maintained in community settings.

Background Few studies have investigated the built environment and its association with health—especially excess adiposity—and physical activity in the immediate pre-Baby Boom/early-Baby Boom generations, soon to be the dominant demographic in the U.S. The purpose of this study was to examine this relationship. Methods This study used a cross-sectional, multilevel design with neighborhoods as the primary sampling unit (PSU). Residents (N=1221; aged 50–75) were recruited from 120 neighborhoods in Portland OR. The independent variables at the PSU level involved GIS-derived measures of land-use mix, distribution of fast-food outlets, street connectivity, access to public transportation, and green and open spaces. Dependent variables included resident-level measures of excess adiposity (BMI ≥25), three walking activities, and physical activity. Data were collected in 2006–2007 and analyzed in 2007. Results Each unit (i.e., 10%) increase in land-use mix was associated with a 25% reduction in the prevalence of overweight/obesity. However, a 1-SD increase in the density of fast-food outlets was associated with a 7% increase in overweight/obesity. Higher mixed-use land was positively associated with all three types of walking activities and the meeting of physical activity recommendations. Neighborhoods with high street connectivity, high density of public transit stations, and green and open spaces were related in varying degrees to walking and the meeting of physical activity recommendations. The analyses adjusted for neighborhood- and resident-level sociodemographic characteristics. Conclusions Findings suggest the need for public health and city planning officials to address modifiable neighborhood-level, built-environment characteristics to create more livable residential communities aimed at both addressing factors that may influence unhealthy eating and promoting active, healthy lifestyles in this rapidly growing population.

Background:This study was designed to develop an evidence- and community-based falls prevention program—Tai Chi: Moving for Better Balance.Methods:A mixed qualitative and quantitative approach was used to develop a package of materials for program implementation and evaluation. The developmental work was conducted in 2 communities in the Pacific Northwest. Participants included a panel of experts, senior service program managers or activity coordinators, and older adults. Outcome measures involved program feasibility and satisfaction.Results:Through an iterative process, a program package was developed. The package contained an implementation plan and class training materials (ie, instructor’s manual, videotape, and user’s guidebook). Pilot testing of program materials showed that the content was appropriate for the targeted users (community-living older adults) and providers (local senior service organizations). A feasibility survey indicated interest and support from users and providers for program implementation. A 2-week pilot evaluation showed that the program implementation was feasible and evidenced good class attendance, high participant satisfaction, and interest in continuing Tai Chi.Conclusions:The package of materials developed in this study provides a solid foundation for larger scale implementation and evaluation of the program in community settings.

INTRODUCTION: Exercise is effective in reducing falls in people with Parkinson disease. However, information on the cost effectiveness of this approach is lacking. We conducted a cost-effectiveness analysis of Tai Ji Quan for reducing falls among patients with mild-to-moderate Parkinson disease. METHODS: We used data from a previous intervention trial to analyze resource use costs related to intervention delivery and number of falls observed during a 9-month study period. Cost effectiveness was estimated via incremental cost-effectiveness ratio (ICER) in which Tai Ji Quan was compared with 2 alternative interventions (Resistance training and Stretching) on the primary outcome of per fall prevented and the secondary outcome of per participant quality-adjusted life years (QALY) gained. We also conducted subgroup and sensitivity analyses. RESULTS: Tai Ji Quan was more effective than either Resistance training or Stretching; it had the lowest cost and was the most effective in improving primary and secondary outcomes. Compared with Stretching, Tai Ji Quan cost an average of $175 less for each additional fall prevented and produced a substantial improvement in QALY gained at a lower cost. RESULTS from subgroup and sensitivity analyses showed no variation in cost-effectiveness estimates. However, sensitivity analyses demonstrated a much lower ICER ($27) when only intervention costs were considered. CONCLUSION: Tai Ji Quan represents a cost-effective strategy for optimizing spending to prevent falls and maximize health gains in people with Parkinson disease. While these results are promising, they warrant further validation. Language: en

OBJECTIVES: To determine the relative effects of cobblestone mat walking, in comparison with regular walking, on physical function and blood pressure in older adults. DESIGN: Randomized trial with allocation to cobblestone mat walking or conventional walking. SETTING: General community in Eugene, Oregon. PARTICIPANTS: One hundred eight physically inactive community-dwelling adults aged 60 to 92 (mean age � standard deviation 577.5 � 5.0) free of neurological and mobility-limiting orthopedic conditions. INTERVENTION: Participants were randomized to a cobblestone mat walking condition (n 554) or regular walking comparison condition (n 554) and participated in 60-minute group exercise sessions three times per week for 16 consecutive weeks. MEASUREMENTS: Primary endpoint measures were balance (functional reach, static standing), physical performance (chair stands, 50-foot walk, Up and Go), and blood pressure (systolic, diastolic). Secondary endpoint measures were Short Form-12 physical and mental health scores and perceptions of health-related benefits from exercise. RESULTS: At the 16-week posttest, differences between the two exercise groups were found for balance measures (P 5.01), chair stands (Po.001), 50-foot walk (P 5.01), and blood pressure (P 5.01) but not for the Up and Go test (P 5.14). Although significant within-group changes were observed in both groups for the secondary outcome measures, there were no differences between intervention groups. CONCLUSION: Cobblestone mat walking improved physical function and reduced blood pressure to a greater extent than conventional walking in older adults. Additional benefits of this walking program included improved health-related quality of life. This new physical activity may provide a therapeutic and health-enhancing exercise alternative for older adults. J Am Geriatr Soc 2005.

Objective: To examine the relation between built environment factors (representing several dimensions of urban form of neighbourhoods) and walking activity at both the neighbourhood level and the resident level, in an older adult sample. Design, setting, participants: A cross sectional, multilevel design with neighbourhoods as the primary sampling unit and senior residents as the secondary unit. Five hundred and seventy seven residents (mean age = 74 years, SD = 6.3 years) participated in the survey, which was conducted among 56 city defined neighbourhoods in Portland, Oregon, USA. Neighbourhood level variables were constructed using geographical information systems. Resident level variables consisted of a mix of self reports and geocoded data on the built environment. Main outcome measure: Self reported neighbourhood walking. Main results: A positive relation was found between built environment factors (density of places of employment, household density, green and open spaces for recreation, number of street intersections) and walking activity at the neighbourhood level. At the resident level, perceptions of safety for walking and number of nearby recreational facilities were positively related to high levels of walking activity. A significant interaction was observed between number of street intersections and perceptions of safety from traffic. Conclusions: Certain neighbourhood built environment characteristics related to urban form were positively associated with walking activity in the neighbourhoods of senior residents. Public health promotion of walking activity/urban mobility and the design of interventions need to consider the contribution of neighbourhood level built environment influences.

LI, F., P. HARMER, K. J. FISHER, and E. MCAULEY. Tai Chi: Improving Functional Balance and Predicting Subsequent Falls in Older Persons. Med. Sci. Sports Exerc., Vol. 36, No. 12, pp. 2046–2052, 2004. Purpose: To determine whether improved functional balance through a Tai Chi intervention is related to subsequent reductions in falls among elderly persons. Methods: Two hundred fifty-six healthy, physically inactive older adults aged 70–92 (mean age SD 77.48 4.95), recruited from a local health system in Portland, OR, participated in a 6-month randomized controlled trial, with allocation to Tai Chi or exercise stretching control, followed by a 6-month postintervention follow-up. Functional balance measures included Berg balance scale, dynamic gait index, and functional reach, assessed during the 6-month intervention period (baseline, 3-month, and 6-month intervention endpoint) and again at the 6-month postintervention follow-up. Fall counts were recorded during the 6-month postintervention follow-up period. Data were analyzed through intention-to-treat analysis of variance and logistic regression procedures. Results: Tai Chi participants who showed improvements in measures of functional balance at the intervention endpoint significantly reduced their risk of falls during the 6-month postintervention period, compared with those in the control condition (odds ratio (OR), 0.27, 95% confidence interval (CI), 0.07–0.96 for Berg balance scale; OR, 0.27, 95% CI, 0.09–0.87 for dynamic gait index; OR, 0.20, 95% CI, 0.05–0.82 for functional reach). Conclusions: Improved functional balance through Tai Chi training is associated with subsequent reductions in fall frequency in older persons. Key Words: BALANCE, FALL PREVENTION, AGING

Objectives:This study examined the relationship between physical activity and self-rated health in older adults at both the neighborhood level and the resident level.Methods:A multilevel design was used that involved neighborhoods as the primary sampling unit and residents nested within each neighborhood. Residents (N = 582, mean age = 73.99 years, SD = 6.26) from 56 neighborhoods in Portland, Oregon, were surveyed on neighborhood physical activity and health status.Results:Multilevel path analysis showed a positive relationship between physical activity and health status at the neighborhood level. In addition, perceptions of neighborhood social cohesion, proximity to physical activity facilities, safety for walking, and importance of physical activity involvement, were positively related to high levels of physical activity. At the resident level, education and walking efficacy were positively associated with physical activity.Conclusions:The results provide evidence that neighborhood-level physical activity is positively linked to neighborhood-level self-rated health in older adults.

It is important that studies on youth health behavior obtain sufficiently large representative samples so that power is adequate and results are generalizable. Few researchers, however, have documented procedures and methods for recruitment of a random stratified youth sample for studies on health-related behavior, specifically physical activity. This study describes the recruitment methods used to attain a stratified sample of 360 target youth (male and female from 10-, 12-, and 14-year old cohorts), and a parent of each child, representing families in 58 different neighborhoods. A peer of each target youth was also invited to participate. Recruitment was conducted primarily by telephone, using computer-assisted telephone interviewing (CATI) software. Approximately 38% of calls resulted in person contact, of which about 98% of families did not qualify. Of those qualified, about 68% agreed to participate. The telephone recruitment was supplemented by door-to-door recruitment in selected neighborhoods. The average cost of telephone recruitment was approximately $99 per family. Advantages and limitations of the recruitment method are discussed.

There is a need for greater understanding of setting-specific influences on physical activity to complement the predominant research paradigm of individual-centered influences on physical activity. In this study, the authors used a cross-sectional multilevel analysis to examine a range of neighborhood-level characteristics and the extent to which they were associated with variation in self-reported physical activity among older adults. The sample consisted of 582 community-dwelling residents age 65 years and older (M = 73.99 years, SD = 6.25) recruited from 56 neighborhoods in Portland, OR. Information collected from participants and neighborhood data from objective sources formed a two-level data structure. These hierarchical data (i.e., individuals nested within neighborhoods) were subjected to multilevel structural-equation-modeling analyses. Results showed that neighborhood social cohesion, in conjunction with other neighborhood-level factors, was significantly associated with increased levels of neighborhood physical activity. Overall, neighborhood-level variables jointly accounted for a substantial variation in neighborhood physical activity when controlling for individual-level variables.

This study examined the effects of a 6-month Tai Chi exercise program on health-related quality of life (HRQL) in older individuals. Using a randomized controlled trial, ninety-four local community-residing volunteers aged 65-96 (M age = 72.8 years, SD = 5.1) were randomly assigned to a 6-month, twice a week, Tai Chi condition or a wait-list control condition. The Short-Form General Health Survey (SF-20) was used to assess change in multiple dimensions of health status involving physical-, social-, and rolefunctioning, bodily pain, mental health, and health perceptions. Results showed that, compared to the control group, participants in the Tai Chi group reported significant improvements in all functional domains of HRQL over the course of the 6-month intervention. It was concluded that a 6-month Tai Chi exercise program is effective for improving HRQL among older adults. Tai Chi, a self-paced and low intensity activity appears to be an effective, low-cost approach for promoting health in older persons.

This study examined the effect of cobblestone-mat walking on health-related outcomes in older adults. Participants (mean age 72.6, N=40) were randomized into either an 8-week cobblestone-mat walking activity (n = 22) or a control group (n = 18). Cobblestone-mat walking entailed three 45-min sessions per week. Primary outcomes included SF-12 (mental, physical), instrumental activities of daily living (IADLs), psychophysical well-being, daytime sleepiness, and pain. Secondary outcomes included resting blood pressure and perceived control of falls. The walkers experienced significantly improved SF-12 scores, IADLs, and psychophysical well-being and significantly reduced daytime sleepiness and pain. They also reported significantly improved perceptions of control over falls. A significant between-groups difference in resting diastolic blood pressure was observed, with reductions in the walkers. A significant within-group reduction in systolic blood pressure was observed in the walkers only. The data indicate that cobblestone-mat walking can significantly improve health-related outcomes in older adults.

Background: Through a re-analysis of a Tai Chi intervention data set, the study objective was to determine which, if any, subgroups of the study sample evidenced differential benefits from the intervention. Method: Re-analysis of a Tai Chi intervention study, a randomized controlled trial in Eugene and Springfield, Oregon. Physically inactive participants aged ≥65 years were randomly assigned to one of two groups: Tai Chi ( n =49) and a wait-list control ( n =45). The main outcome measure was self-reported physical function. Results: Initial latent curve analyses indicated significant Tai Chi training effects: Participants in the Tai Chi group reported significant improvements in perceived physical function compared to those in the control group. However, there was significant interindividual variability in response to Tai Chi. The overall intervention effect was further delineated by identifying two subgroups. This delineation showed that Tai Chi participants with lower levels of physical function at baseline benefited more from the Tai Chi training program than those with higher physical function scores. Inclusion of additional measures of individual characteristics at baseline, change in movement confidence, and class attendance further explained differences in treatment responses. Conclusions: Findings from this study suggest that although an intervention may show an overall effect (or no overall effect), it may be differentially effective for subgroups of participants that differ in their pre-intervention characteristics. Examination of variability in outcome measures can provide important information for refining and tailoring appropriate interventions targeted to specific subgroups.

In recent years, a number of statistical techniques for the analysis of longitudinal multilevel data have become available, allowing researchers the opportunity to study behavior at different levels (e.g., individual, family, school, neighborhood). Although many of these statistical approaches are widely available, they are still relatively underused, and there is uncertainty among researchers as to the appropriateness and usefulness of different approaches for analyzing longitudinal data. The purpose of this article is to present an extension of the general latent variable growth curve modeling framework to 4 levels of the hierarchy. This 4-level extension merges 2 common analytic approaches used in answering longitudinal multilevel research questions: (a) a full information maximum likelihood (ML) latent growth modeling approach using an extension of a factor-of-curves model and (b) a limited information multilevel latent growth modeling (LGM) approach using Muthen's ML-based estimator. Data comprised r...

A 3‐D tomographic inversion approach based on a surface‐consistent model for static corrections is presented in this paper. Direct, reflected, and refracted waves are used simultaneously to update the near‐surface model. We analyze the characteristics of the first‐break traveltime in complicated low‐velocity layers. To improve the accuracy for the velocity model, the various first‐break times from direct, reflected, and refracted waves are considered for model inversion. A fractal algorithm which overcomes the error caused by wavelet shape differences is applied to pick first breaks. It also overcomes the leg jump of refractions. The method can pick a large number of first breaks automatically. The raypaths and traveltimes are calculated with a 3‐D ray tracer that does not increase computation time for complicated geological models. Our method can determine the raypath associated with minimum traveltimes regardless of wave mode (direct, refracted, or reflected). We use a least‐squares approach in conjunction with a matrix decomposition to reconstruct a 3‐D velocity model from the actual first‐break times obtained from 3‐D data. Finally, long‐ and short‐wavelength static corrections are calculated concurrently, based on the reconstructed velocity profile. The method can be applied to wide‐line profiles, crooked lines, and 2‐D and 3‐D seismic survey geometries. The results applied to a real 3‐D data example indicate that the 3‐D tomographic static corrections are effective for field data.

Data collected from 294 young adults, ages 19 to 25, and both a same- and an opposite-gender best friend or mate across 3 annual assessments were analyzed to examine the similarity to and influence of the peer on the young adult's substance use. The authors found similarity across time between both peers and the young adult in cigarette use, alcohol use, binge drinking, and, in most cases, marijuana use. In prospective analyses, peer use predicted young adult cigarette use, binge drinking, and problem use by the young adults. Results were generally consistent across gender and for both same- and opposite-gender peers. Findings emphasize peer influence contribution to young adult substance use and suggest the design of interventions that involve both young adults and their peers.

Using a randomized controlled trial, this study examined whether a 6-month Tai Chi exercise program enhanced elderly individuals' multidimensional, hierarchical physical self-esteem. Participants either continued their daily routine activities or participated in a Tai Chi exercise class performing slow rhythmic movements. Both global and domain-specific physical esteem measures were assessed at baseline, at 3 months, and at the 6-month termination of the intervention. Growth curve models were used to analyze the repeated-measures data. Results indicated that individuals who participated in the 6-month Tai Chi exercise program showed increased levels of global self-esteem, domain-specific physical self-worth, and subdomain-specific esteem of attractive body, physical strength, and physical condition. Thus, Tai Chi, a simple, low-cost form of physical activity, has the potential to alter favorably specific facets of physical self-worth/ esteem in older adults, which may in turn enhance important aspects of their quality of life.

This paper presents a latent growth SEM approach for the estimation of treatment effects, and power to detect such effects, within a true experimental design setting in which subjects are randomly assigned to treatment and control conditions. Power estimation is a critical component of intervention experiment design and the testing of their results. Although researchers have become increasingly sophisticated in applying tests for statistical significance in intervention contexts, few are aware of the power of these tests. The issues raised in this paper are not new; however, reminding researchers to consider these points is important. Exactly how the researcher handles these issues will depend on the questions asked and the resources available, as well as other considerations. Discussion underscores the relationship between the reliability of a study's measures and concomitant increases in power obtained within the SEM framework.

This study examines heterogeneity in the developmental trajectories of alcohol use in adolescents and the accompanying trajectory-specific longitudinal influence of exposure to their deviant peers. Using a national data set on alcohol use (N = 188), a growth mixture model capturing growth trajectories in adolescent alcohol use from ages 14 to 18 years was first examined. This was followed by an investigation of age-varying influences of peers on adolescent alcohol use and the co-development of peer influence and adolescent alcohol use. Results of growth mixture modeling of repeated-measures data on adolescent alcohol use showed two distinct latent classes of developmental trajectory with significant differences in levels of use. Analyses of exposure to deviant peer and adolescent alcohol use variables indicated differential effects of peers across trajectory classes. Stronger prospective influences for the trajectory group having a low initial status of use were found. Findings from this study suggest the need to consider heterogeneity in the study of peer influence on alcohol use during adolescence to facilitate more refined targeting of prevention/intervention programs.

Although it has been established that health benefits can be gained from low to moderate levels of regular physical activity for all ages, a significant proportion of the elderly population remains sedentary, especially in developed countries. Despite the fact that the elderly population has much to gain from adopting health-promoting behaviors such as regular exercise, significant psychological, social, and environmental barriers remain. The Senior Health and Physical Exercise (SHAPE) project is a randomized controlled trial, which adopts an ecological approach to identifying, recruiting and promoting physical activity among populations of inactive elderly citizens in an urban setting. Bandura's Social Cognitive Theory incorporating self-efficacy factors, exercise behavior and neighborhood environment, underpins the planning and implementation of this project. This study identifies the heterogeneity of demographic characteristics, and examines related social and environmental influences enhancin...

This study was designed to determine the relationship between physical activity and the task-switching aspect of executive function by investigating the modulating roles of age, modality of physical activity, and type of cognitive function using behavioral and event-related potential (ERP) assessments. Sixty-four participants were assigned to one of four groups based on age and history of physical activity: older adults performing endurance exercise (OEE), older adults practicing Tai Chi Chuan (OTC), older adults with a sedentary lifestyle (OSL), and young adults (YA). Study participants completed a task-switching task under homogeneous and heterogeneous conditions while ERPs were recorded. The results revealed that YA had shortest reaction times compared with the three older adults groups, with OSL exhibiting the longest reaction time. YA also exhibited shorter P3 latency than OSL. No differences were observed in P3 amplitude between YA, OEE, and OTC; however, all three groups had significantly larger P3 amplitude compared with OSL in both task conditions. In conclusion, age and participation in physical activity influence the relationship between physical activity and task-switching, and a positive relationship was observed regardless of the modality of physical activity and type of cognitive function. Our ERP findings support the model of the scaffolding theory of aging and cognition (STAC) and suggest that regular participation in endurance exercise and Tai Chi Chuan may have equivalent beneficial effects on cognition at the behavioral and neuroelectric levels.

Fuzhong Li1,2 1Oregon Research Institute, Eugene, OR, USA; 2Shanghai University of Sport, Shanghai, People’s Republic of ChinaBackground: Limits of stability, defined as the ability to maintain the center of gravity within the boundary of the base of support, is critically important for older adults in performing their activities of daily living. However, few exercise programs specifically tailored to enhance limits of stability exist. The primary purpose of this study was to determine whether a therapeutically designed intervention, Tai Ji Quan: Moving for Better Balance (TJQMBB), could improve limits of stability in older adults. A secondary purpose was to examine concomitant change in limits of stability and physical performance as a result of the intervention.Methods: A single-group design was used in which 145community-dwelling older adults (average age: 75years) were enrolled in TJQMBB classes, participating twice weekly for 48weeks. Primary outcome measures were three indicators of limits of stability (LOS) (endpoint excursion, movement velocity, and directional control), with secondary measures of physical performance being Timed Up and Go and 50-foot speed walk (in seconds), which were assessed at baseline, 24weeks, and 48weeks. Changes in the repeated measures of outcome variables were analyzed via latent curve analysis.Results: At 48weeks, a significant rate of change (improvement) over time was observed in the three limits of stability indicators (endpoint execution: 8.30% LOS, P

Recent developments in finite mixture modeling allow for the identification of different developmental processes in distinct but unobserved subgroups within a population. The new approach, described within the general growth mixture modeling framework (Muthen, 2001, in press), extends conventional random coefficient growth models to incorporate a categorical latent trajectory variable representing latent classes or mixtures (i.e., the subgroups in the population whose membership must be inferred from the data). This article provides a didactic example of this new methodology with adolescent alcohol use data, which is shown to consist of a mixture of distinct subgroups, defined by unique growth trajectories and differing predictors and sequelae. The method is discussed as a useful tool for mapping hypotheses of development onto appropriate statistical models.

The replicability of a model of family and peer influences on adolescent problem behavior was evaluated with samples of adolescent boys and girls from three ethnic groups: American Indians, Hispanics, and Caucasians. Participants were 1,450 seventh-grade students from 16 communities. The model included links between three aspects of family functioning (family conflict, positive family relations, and inadequate parental monitoring) and adolescents’ association with deviant peers. Those variables were hypothesized predictors of adolescents’ problem behavior (antisocial behavior, poor school performance, and frequency of substance use). The resulting cross-sectional model showed good consistency across the three ethnic groups for both genders, but some subgroup differences emerged in the magnitude of relations between monitoring and adolescents’ associations with deviant peers and between substance use and the problem behavior construct. With those qualifications, the model was applicable to Hispanic and Native American adolescents in the sample.

This article addresses issues of heterogeneity in multiple-stage development as it corresponds to qualitatively different development in alcohol use during adolescence. Using a piecewise growth mixture modeling methodology proposed by Muthen (in press), a 2-piece linear growth model capturing growth trajectories in adolescent alcohol use during the transition from middle school (ages 11 to 13) to high school (ages 14 to 17; N = 81) was examined. It was hypothesized that 2 stages of alcohol use development with varying trajectories would exist in these data, the 1st corresponding to development during middle school (Growth Rate 1), followed by a 2nd stage of continuing growth during high school (Growth Rate 2). Results suggested the tenability of the 2-piece linear development in alcohol use and the emergence of 2 latent classes with individually varying transition points. Class 1 showed linear increases only during high school, whereas Class 2 showed a continued, linear growth throughout the middle and hi...

Using a randomized controlled trial, this study examined whether a Tai Chi exercise program enhanced elderly individuals' psychological well-being. Participants either continued their daily routine activities or participated in a Tai Chi exercise class performing slow rhythmic movements. Psychological well-being measures were assessed at baseline, 3 months, and 6 months (termination of the class). Latent growth curve modeling methodology was used to analyze the repeated measures data. Results indicated that individuals who participated in the 6-month Tai Chi exercise program showed higher levels of health perceptions, life satisfaction, positive affect, and well-being and lower levels of depression, negative affect, and psychological distress. The implications of these findings are discussed relative to potential underlying mechanisms associated with the exercise-psychological health relation in older adults.

Using Tai Chi as an exercise mode, this study examined the association between self-efficacy and physical function. Ninety-four healthy, physically inactive older adults (M age = 72.8 years, SD = 5.1) were randomly assigned to either a 6-month, twice a week, Tai Chi condition or a wait-list control condition. Outcome variables included self-reports of movement efficacy and physical function assessed at baseline, middle, and termination of the study. Multisample latent curve analyses revealed a significant rate of change attributable to the Tai Chi intervention in both self-efficacy and physical function, with participants experiencing significant improvements over the course of the intervention. Analyses also showed a positive association between self-efficacy and physical function, indicating that improvements in older adults' self-efficacy of movement as a function of Tai Chi were related to increased levels of perceived physical capability. This study uncovered the need for further exploration of the relationship between exercise self-efficacy and physical function for enhancing health-related quality of life in older adults.

This article presents an extension of Joreskog and Yang's (1996) method of estimating interaction effects among latent variables to latent growth curve models. Models involving a product of 2 latent factors of either static or dynamic variables (parental monitoring and rule-setting) predicting an outcome growth variable (adolescents' initial status and rate of change in antisocial behavior) are used as substantive illustrations. The results are discussed in terms of practical and statistical problems associated with interaction analyses in latent curve models, and in structural equation models with latent variables in general.

The stability and validity of early adolescents' reports of 6 parenting constructs were examined: parent-child conflict, positive family relations, parental monitoring, parents' rule making, consistent enforcement of rules, and use of positive reinforcement. Hierarchical confirmatory factor analysis (CFA; H. W. Marsh & D. Hocevar, 1988) on questionnaire data from 3 quarterly assessments of 174 5th-7th grade youth was used to test a multitrait-multimethod (MTMM) model containing 6 parenting constructs as trait factors and 3 assessment occasions as method factors. Youths' reports of these parenting constructs were stable over time, and the CFA approach to MTMM data demonstrated convergent and discriminant validity of the constructs. Each parenting construct was significantly correlated with youths' reports of deviant peer associations, antisocial behavior, and substance use, providing evidence of criterion validity.

Although a number of factor analytic studies have been conducted on the factorial validity of the Task and Ego Orientation in Sport Questionnaire (TEOSQ), the results have been equivocal. To further substantiate its evidence of validity, this study cross-validated the measurement model using a rigorous structural equation modeling (SEM) approach. Data collected from a college student sample were first analyzed on a calibration sample (n = 439). Results confirmed the two-factor orthogonal structure representing the underlying task and ego orientations. The results were cross-validated on a validation sample (n = 439) using various SEM-based cross-validation procedures. Collectively, these findings support the construct validity of the TEOSQ as a measure of achievement goal orientation.

Data collected from longitudinal designs often have correlated observations arising from repeated measurements on the same subject. Conventional statistical methods (e.g., ordinary least squares linear regression, univariate analysis of variance with repeated measures) that assume independence of observations can be inadequate in providing test statistics. Liang and Zeger (1986) proposed a class of generalized estimating equations (GEE) to account for dependence among observations. The article provides a descriptive introduction to GEE and an example illustrating its use in continuous response data with a multivariate normal distribution. A discussion on the utility of the GEE procedure in longitudinal data analysis is provided.

Nearly all psychosocial survey datasets contain missing data. Recent advances in statistical theory, and implementation of the theory in modeling software, have made it possible to handle various types of missing data with the proviso that data are missing at random. This study presents an application of a confirmatory factor analysis with incomplete data, demonstrating the utility of several maximum likelihood-based missing data estimation procedures: multigroup, single group, and expectation maximization multiple-imputation. The substantive example used to demonstrate these procedures was a 2-factor measurement model of achievement goal orientation in sports with a sample size of 1,002. Of the total sample, 124 participants (12%) had incomplete data in the form of nonresponse. Initial analysis showed that the data missing were completely random. Subsequent modeling of the incomplete data revealed that, across the 3 data estimation procedures, parameter estimates were remarkably similar and standard erro...

Longitudinal data sets typically suffer from attrition and other forms of missing data. Omissions, attrition, and planned missingness have limited our ability to conduct the most appropriate analyses. When this common problem occurs, several researchers have demonstrated that correct estimation with missing data can be obtained under mild assumptions concerning the missing data mechanism. An example application of latent growth curve methodology, analyzing the longitudinal developmental change in adolescent alcohol consumption, is presented (N = 586; 250 young men and 336 young women, 14 to 16 years of age at the initial time point). The analyses are conducted within a cohort‐sequential design, incorporating missingness introduced by design and due to attrition. We describe and illustrate 3 approaches to the analysis of missing data when some data are missing: multiple‐sample structural equation modeling procedures, raw maximum likelihood analyses, and multiple modeling and data augmentation algorithms.

Confirmatory factor analysis (CFA) is often used in the social sciences to estimate a measurement model in which multiple measurement items are hypothesized to assess a particular latent construct. This article presents the utility of multilevel CFA (MCFA; Muthen, 1991, 1994) and hierarchical linear modeling (HLM; Raudenbush, Rowan, & Kang, 1991) methods in testing measurement models in which the underlying attribute may vary as a function of various levels of observation. An illustrative example using a real dataset is provided in which an unconditional model specification and parameter estimates from the MCFA and HLM are shown. The article demonstrates the comparability of the two methods in estimating measurement parameters of interest (i.e., true variance at levels the measures are used and measurement errors).

Data in social science research often have a multilevel structure, with observations on individuals nested within groups. However, such data have been routinely analyzed at the individual level, whereas the group level variation has been ignored. Recent developments in multilevel covariance structure modeling (MCSM; Muthen, 1994) provide a useful statistical tool for analyzing sources of variation due to both within- and between-group influences. The purpose of this study is to illustrate the use of multilevel confirmatory factor analysis (MCFA) via a didactic example of a 2-level (student vs. class) analysis of exercise intrinsic motivation to experience sensations (IM-ES) data. Application of MCFA revealed substantial variation in the IM-ES at both student and class levels. In addition, predictors designed to explain the between-class levels of IM-ES (class size, type of instructor, and type of activity) significantly predicted the class-level variation in the IM-ES. The study demonstrated the merit of ...