Jeremy J. Bauer

Jumping Improves Hip and Lumbar Spine Bone Mass in Prepubescent Children: A Randomized Controlled Trial

Physical activity during childhood is advocated as one strategy for enhancing peak bone mass (bone mineral content [BMC]) as a means to reduce osteoporosis‐related fractures. Thus, we investigated the effects of high‐intensity jumping on hip and lumbar spine bone mass in children. Eighty‐nine prepubescent children between the ages of 5.9 and 9.8 years were randomized into a jumping (n = 25 boys and n = 20 girls) or control group (n = 26 boys and n = 18 girls). Both groups participated in the 7‐month exercise intervention during the school day three times per week. The jumping group performed 100, two‐footed jumps off 61‐cm boxes each session, while the control group performed nonimpact stretching exercises. BMC (g), bone area (BA; cm2), and bone mineral density (BMD; g/cm2) of the left proximal femoral neck and lumbar spine (L1‐L4) were assessed by dual‐energy X‐ray absorptiometry (DXA; Hologic QDR/4500‐A). Peak ground reaction forces were calculated across 100, two‐footed jumps from a 61‐cm box. In addition, anthropometric characteristics (height, weight, and body fat), physical activity, and dietary calcium intake were assessed. At baseline there were no differences between groups for anthropometric characteristics, dietary calcium intake, or bone variables. After 7 months, jumpers and controls had similar increases in height, weight, and body fat. Using repeated measures analysis of covariance (ANCOVA; covariates, initial age and bone values, and changes in height and weight) for BMC, the primary outcome variable, jumpers had significantly greater 7‐month changes at the femoral neck and lumbar spine than controls (4.5% and 3.1%, respectively). In repeated measures ANCOVA of secondary outcomes (BMD and BA), BMD at the lumbar spine was significantly greater in jumpers than in controls (2.0%) and approached statistical significance at the femoral neck (1.4%; p = 0.085). For BA, jumpers had significantly greater increases at the femoral neck area than controls (2.9%) but were not different at the spine. Our data indicate that jumping at ground reaction forces of eight times body weight is a safe, effective, and simple method of improving bone mass at the hip and spine in children. This program could be easily incorporated into physical education classes.

Physical activity beliefs and behaviour of adults with physical disabilities

Purpose. The purpose of this study was to elicit the physical activity (PA) beliefs from adults with physical disabilities; and second, to examine their self-reported PA participation. Method. Participants were 223 adults (M age = 45.4 years, SD = 10.8), with self-reported physical disabilities who completed a web-based survey. Six open-ended questions were used to assess PA beliefs and the PA Scale for Individuals with Physical Disabilities measured self-reported PA. Results. A qualitative analysis showed that the most accessible behavioural advantages are that PA improves emotional functioning and assists with weight management. The most accessible behavioural disadvantages are that PA causes pain or soreness and consumes time. The most accessible normative influences that approve of PA are family, friends, and healthcare professionals. The most accessible control beliefs obstructing PA are disability and associated symptoms, and a lack of access to adequate facilities, equipment, or programs. The most accessible control beliefs that facilitate PA are access to adequate facilities, equipment, or programs, and support or assistance. Finally, the average total PA score was 20.5 metabolic equivalent (METS)-hours/day (SD = 16.8). Conclusions. Adults with physical disabilities possess unique PA beliefs that can be used to design health promotion interventions to increase PA participation.

Longitudinal changes in psychosocial constructs and physical activity among adults with physical disabilities.

BACKGROUND Given the importance of physical activity (PA) and the low activity levels among adults with physical disabilities, it is important to understand how temporal changes in psychosocial constructs affect PA changes over time. OBJECTIVE/HYPOTHESIS Examine if changes in the transtheoretical model (TTM) constructs affected changes in PA levels over time. METHODS One hundred thirty-two adults with physical disabilities, such as multiple sclerosis and spinal cord injuries, completed a web-based survey once every 4 months, for a total of 3 time points, to assess the TTM constructs and PA. Six latent growth curve analyses were conducted using Mplus(5) to examine if longitudinal changes in the TTM constructs affected temporal changes in PA levels. RESULTS All six hypothesized models fit the sample data well (e.g., χ(2) = NS; RMSEA = <.001-.06). In a descending order of significance, the best predictors of the initial levels of PA were the stages of change, the behavioral processes of change, the cognitive processes of change, self-efficacy, and perceived pros. The meaningful predictors of PA changes over time were the initial levels and the slopes of the cognitive processes of change, perceived pros, and the behavioral processes of change. Although the slopes of the stages of change and perceived cons did not have a statistically significant effect on PA changes, their effects approached a medium size (.33 and .38, respectively). CONCLUSIONS In order to reassure the maintenance of an exercise program, interventionists need to first emphasize cognitive, motivational strategies (cognitive processes of change), such as the importance of PA and positive thoughts about exercise participation as well as exercise benefits (pros) before they implement behavioral strategies (behavioral processes of change), such as social support, goal setting, and self-rewarding.

Psychosocial predictors of physical activity and health-related quality of life among adults with physical disabilities: an integrative framework.

BACKGROUND People with disabilities report lower physical activity (PA) and health-related quality of life (HRQOL) levels than people without disabilities. Therefore, it is important to identify factors that motivate individuals with disabilities to be physically active and thus increase their HRQOL. OBJECTIVES The purpose of the study was to prospectively explore the effects of past theory of planned behavior (TPB) constructs on future (6-month) HRQOL (physical and mental health) through past stages of change (SOC) and future (6-month) PA among adults with physical disabilities. Two models were tested whereby the SOC and PA served as the mediators between the TPB constructs, physical health (PH-Model), and mental health (MH-Model). It was hypothesized that both models would fit the sample data. METHODS Participants were 141 adults with physical disabilities (mean age = 46.04, females = 70.9%). The online survey was completed at two different time periods. First, the TPB constructs and SOC were assessed using self-report standardized questionnaires. Six months later, participants completed standardized self-report scales about their PA and HRQOL levels. Using LISREL 8, two path analyses were conducted to examine the two study models (PH-Model and MH-Model). RESULTS Based on the two path analyses, attitude had the highest effect on SOC followed by perceived behavioral control within both well-fit models. The PH-Model explained more variance in PA (26%) and physical health (55%) than the MH-Model. CONCLUSIONS Health promoters should reinforce both positive intentions and behavioral experiences to increase PA and HRQOL among adults with physical disabilities.

The Accuracy of Photo-Based Three-Dimensional Scanning for Collision Reconstruction Using 123D Catch

An experiment was conducted to examine the validity of freely available photo-based 3D scanning software for generating accurate 3D geometry of a vehicle. Currently, 3D vehicle geometry is routinely captured using total station survey equipment, coordinate measuring machines (CMM), laser scanning, or traditional point-based photogrammetry. While these methods produce sufficiently accurate results for collision reconstruction, they have limitations that can affect practical implementation. For example, manual surveying with a total station, CMM or traditional photogrammetry are all limited to the production of coordinate data at discrete, predefined points. In addition, total stations, CMMs and laser scanning devices are also expensive and require a significant amount of time in the field with the vehicle. In contrast, photo-based 3D scanning allows a 3D mesh to be created of a vehicle simply from a series of photographs using a consumergrade digital camera.

Do temporal scores of motivational constructs correspond with physical activity levels

BACKGROUND Adults with physical disabilities typically engage in low levels of physical activity (PA), thus a better understanding of how motivational factors and behavior vary over time and in relation to disability type and severity is needed. OBJECTIVE/HYPOTHESIS To examine temporal changes in theory of planned behavior (TPB) constructs and PA by disability type (multiple sclerosis vs. spinal cord injury) and severity (mild, moderate, and severe). METHODS Participants were 77 adults with physical disabilities who completed a web-based survey that assessed the TPB constructs and PA participation. The survey was completed once every four months for a total of three time points. Two-way repeated measures ANOVAs were used to examine if the TPB constructs and PA changed over time and in relation to disability type and severity. RESULTS There was only one significant between-subjects effect for PA by disability severity, F (2, 68) = 5.94, p = .004, η2 = 15%. People with mild disabilities exhibited higher mean PA participation over the three time periods (M = 21.06 ± 11.49 MET-hrs/day) than those with moderate disabilities (M = 11.27 ± 9.3 MET-hrs/day) and severe disabilities (M = 13.43 ± 14.74 MET-hrs/day). CONCLUSIONS Although participants possessed positive PA motivational factors that remained stable over time, their PA participation was low and differed as a function of disability severity. Therefore, PA interventions should be tailored such that individuals with severe disabilities receive the greatest amount of exercise prescription consultations and supervision compared to those with more moderate and mild disabilities.

Impact Forces From Jumping Depend on Jump Height

We thank Dr. Bassey for explaining the statement made in her earlier article regarding the measurement of ground reaction forces. Furthermore, we wish to take this opportunity to respond to her use of “high impact.” In her letter, Dr. Bassey states “Jumping produces high impact, even when the jumps are small and suitable for middle-aged and sedentary adults 8 cm high.” Impact exercise involves the application of force quickly (compared with resistance exercise), and, thus, typically produces relatively high loading rates compared with walking and resistance training. (1) However, we take issue with Dr. Bassey’s definition of “high impact” because, on a continuum, with walking being approximately 1 body weight at the ground and landings from gymnastics ranging from 12 to 18 body weights, 3‐ 4 body weights is not “high” but rather more in the low range of impact forces. Therefore, this type of two-footed jumping is a safe activity for most older adults because it is not high impact and most likely is