Peter Harmer

Tai Chi and Postural Stability in Patients with Parkinson's Disease

BACKGROUND Patients with Parkinsons disease have substantially impaired balance, leading to diminished functional ability and an increased risk of falling. Although exercise is routinely encouraged by health care providers, few programs have been proven effective. METHODS We conducted a randomized, controlled trial to determine whether a tailored tai chi program could improve postural control in patients with idiopathic Parkinsons disease. We randomly assigned 195 patients with stage 1 to 4 disease on the Hoehn and Yahr staging scale (which ranges from 1 to 5, with higher stages indicating more severe disease) to one of three groups: tai chi, resistance training, or stretching. The patients participated in 60-minute exercise sessions twice weekly for 24 weeks. The primary outcomes were changes from baseline in the limits-of-stability test (maximum excursion and directional control; range, 0 to 100%). Secondary outcomes included measures of gait and strength, scores on functional-reach and timed up-and-go tests, motor scores on the Unified Parkinsons Disease Rating Scale, and number of falls. RESULTS The tai chi group performed consistently better than the resistance-training and stretching groups in maximum excursion (between-group difference in the change from baseline, 5.55 percentage points; 95% confidence interval [CI], 1.12 to 9.97; and 11.98 percentage points; 95% CI, 7.21 to 16.74, respectively) and in directional control (10.45 percentage points; 95% CI, 3.89 to 17.00; and 11.38 percentage points; 95% CI, 5.50 to 17.27, respectively). The tai chi group also performed better than the stretching group in all secondary outcomes and outperformed the resistance-training group in stride length and functional reach. Tai chi lowered the incidence of falls as compared with stretching but not as compared with resistance training. The effects of tai chi training were maintained at 3 months after the intervention. No serious adverse events were observed. CONCLUSIONS Tai chi training appears to reduce balance impairments in patients with mild-to-moderate Parkinsons disease, with additional benefits of improved functional capacity and reduced falls. (Funded by the National Institute of Neurological Disorders and Stroke; ClinicalTrials.gov number, NCT00611481.).

Built Environment, Adiposity, and Physical Activity in Adults Aged 50–75

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>or=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.

Tai Chi: improving functional balance and predicting subsequent falls in older persons.

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.

Built Environment and 1-Year Change in Weight and Waist Circumference in Middle-Aged and Older Adults Portland Neighborhood Environment and Health Study

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.

Self-Efficacy as a Mediator Between Fear of Falling and Functional Ability in the Elderly:

Objectives: This study examined falls self-efficacy and fear of falling to determine whether self-efficacy acts as a mediator between fear of falling and functional ability. Methods: Using the Survey of Activities and Fear of Falling in the Elderly as a fear-of-falling measure and the Activities-Specific Balance Confidence Scale for falls self-efficacy, structural relationships among fear of falling, self-efficacy, functional balance, and physical functioning outcomes were tested with older adults (N = 256, M age = 77.5). Results: Lower levels of fear of falling were significantly related to higher levels of falls self-efficacy, which was in turn associated with better functional outcomes. Moreover, falls self-efficacy mediated the effects of fear of falling on functional outcomes. Discussion: Results substantiate the hypothesized mediational role of falls self-efficacy in fear of falling and underscore the need to consider ways of enhancing falls self-efficacy in interventions aimed at reducing falls and fear of falling.

Translation of an Effective Tai Chi Intervention Into a Community-Based Falls-Prevention Program

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.

Testing the Simplex Assumption Underlying the Sport Motivation Scale: A Structural Equation Modeling Analysis

Self-determination theory (Deci & Ryan, 1985) suggests that motivational orientation or regulatory styles with respect to various behaviors can be conceptualized along a continuum ranging from low (a motivation) to high (intrinsic motivation) levels of self-determination. This pattern is manifested in the rank order of correlations among these regulatory styles (i.e., adjacent correlations are expected to be higher than those more distant) and is known as a simplex structure. Using responses from the Sport Motivation Scale (Pelletier et al., 1995) obtained from a sample of 857 college students (442 men, 415 women), the present study tested the simplex structure underlying SMS subscales via structural equation modeling. Results confirmed the simplex model structure, indicating that the various motivational constructs are empirically organized from low to high self-determination. The simplex pattern was further found to be invariant across gender. Findings from this study support the construct validity of the SMS and have important implications for studies focusing on the influence of motivational orientation in sport.

Approaches to Testing Interaction Effects Using Structural Equation Modeling Methodology.

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 Judds 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 Task and Ego Orientation in Sport Questionnaire: Construct Equivalence and Mean Differences across Gender

Research on achievement goal orientation in sport has relied primarily on traditional statistical methodology to examine group mean differences. Unfortunately, examination of the measurement model is generally ignored prior to means testing. This study reports an application of structural equation modeling (SEM) in testing measurement invariance and latent mean structure of the Task and Ego Orientation in Sport Questionnaire (TEOSQ; Duda & Nicholls, 1989) using male and female college students. A confirmatory factor analysis for testing invariance revealed invariant measurement properties and factor structures across gender, indicating that task and ego orientation are similarly conceptualized by male and female students. Subsequent testing of latent mean structures, however, showed significant gender differences with respect to ego orientation, but no difference in task orientation. The SEM procedures used in the present study demonstrate additional construct validity and internal consistency reliability for the TEOSQ and, by confirming its factor structure, provide a sound psychometric basis for its continued use in substantive studies focusing on the comparison of achievement goal orientation across gender.

Epidemiology of injury in Olympic sports

This new volume in the Encyclopaedia of Sports Medicine series, published under the auspices of the International Olympic Committee, provides a state-of-theart account of the epidemiology of injury across a broad spectrum of Olympic sports. The book uses the public health model in describing the scope of the injury problem, the associated risk factors, and in evaluating the current research on injury prevention strategies described in the literature.