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Tobias Kalenscher, Karl-Theodor Kalveram and Jürgen Konczak

This study investigated force adaptation in humans during goal-directed flexion forearm motion. The ability of the motor system to adapt to changes in internal or external forces is essential for the successful control of voluntary movement. In a first experiment, we examined how under- or overdamping differentially affected the length of the adaptation and the arm kinematics between force transitions. We found that transitions diverging from a null-force produced larger transition effects than transitions converging to a null force condition, indicating that re-adaptation was less error-prone. Whether the subjects had previously experienced underdamping or the null-force had no significant impact on the spatial trajectory after switching to overdamping. That is, prior force experience had no differential effect on the spatial transition kinematics. However, the transitions underdamping-to-overdamping and underdamping-to–null force did produce differently strong transition effects. These results indicate that exposure to the new force rather than previous force-field experience is responsible for transition- and after-effects. In a second experiment, we investigated whether learning was law-like—that is, whether it generalized to unvisited workspace. Subjects were tested in new, unvisited workspaces in the null-force condition after sufficient training in either force condition. The occurrence of transferred after-effects indicated that adaptation to both positive and negative damping was mediated by rule-based rather than exclusive associative processes.

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Minsoo Kang, Youngdeok Kim and David A. Rowe

Background:

This study examined the optimal measurement conditions to obtain reliable peak cadence measures using the accelerometer-determined step data from the National Health and Nutrition Examination Survey 2005–2006.

Methods:

A total of 1282 adults (> 17 years) who provided valid accelerometer data for 7 consecutive days were included. The peak 1- and 30-minute cadences were extracted. The sources of variance in peak stepping cadences were estimated using Generalizability theory analysis. A simulation analysis was conducted to examine the effect of the inclusion of weekend days. The optimal number of monitoring days to achieve 80% reliability for peak stepping cadences were estimated.

Results:

Intraindividual variability was the largest variance component of peak cadences for young and middle-aged adults aged < 60 years (50.55%–59.24%) compared with older adults aged ≥ 60 years (31.62%–41.72%). In general, the minimum of 7 and 5 days of monitoring were required for peak 1- and 30-minute cadences among young and middle-aged adults, respectively, whereas 3 days of monitoring was sufficient for older adults to achieve the desired reliability (0.80). The inclusion of weekend days in the monitoring frame may not be practically important.

Conclusions:

The findings could be applied in future research as the reference measurement conditions for peak cadences.

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Karen K. Lee, Candace D. Rutt, Andrea Sharma, Michael Pratt, Judd Flesch, L. Michele Maynard, Keri Kennedy, Peggy Adams and Harold W. Kohl III

Background:

In this article, we examine the possibility of reducing time to conduct traffic volume audits through (1) reducing time for manual traffic counting and (2) using Department of Transportation (DOT) information.

Methods:

In audits of 824 road segments in 2 West Virginia (WV) communities, manual traffic counts were recorded for 1, 2, and 5 minutes in duration. Annual Average Daily Traffic (AADT) was calculated from counts. Available AADT from DOT was also collected. Percent agreement and a weighted kappa were calculated between 5-minute count and 1- and 2-minute count AADT categories and between 5-minute count and DOT AADT categories.

Results:

One- and 2-minute counts produced identical AADT categories as 5-minute counts in 93.4% and 95.0% of segments, respectively. Weighted kappa was 0.79 (95% CI = 0.74–0.85) and 0.85 (95% CI = 0.80–0.89), respectively. Forty-two segments (5.1%) had DOT data.

Conclusions:

DOT AADT was available for a small percentage of road segments assessed. The high agreement between AADT categories produced by 1- and 2-minute counts and 5-minute counts makes it reasonable to consider using 1- or 2-minute manual traffic counts if time or staffing constraints make it necessary. Possible generalizability of this methodology to other communities, particularly larger urban and suburban areas, will require further research.

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Han C.G. Kemper, Jos W.R. Twisk and Willem van Mechelen

In the Amsterdam Growth And Health Longitudinal Study (AGAHLS), a group of approximately 650 12- to 14-year-old boys and girls was followed in their growth, and development of their health their lifestyle including diet, physical activity and smoking. One of the main interests was the change in their aerobic fitness. From 12 to 36 years of age in total, eight repeated measurements were performed to measure peak oxygen uptake (peak VO2). In this study the data of peak VO2 are revisited and extended: We made use of all collected data as a mixed longitudinal design including cross-sectionally measured subjects as well as longitudinally measured subjects. This led to the availability of 1,194 boys and 1356 girls. With generalized estimating equations (GEE) the longitudinal changes with chronological age and differences between boys and girls were analyzed. Teenage boys and girls increased their peak VO2 (ml/min) significantly (p < .001) until age 14 in girls and until age 17 in boys. However peak VO2 relative to bodyweight (peak VO2/BW) had significantly (p < .001) decreased over the whole age range from 12 to 36 in both sexes. Vigorous physical activity (VPA) also showed a decrease and was significantly (p < .001) related with lower peak VO2/BW (Beta = 0.001). This relation was stronger in boys than in girls. Because at the start of AGAHLS no fast responding metabolic instruments were available, future longitudinal studies about aerobic fitness should include also measurement of VO2 kinetics.

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Luke E. Kelly and James H. Rimmer

The subjects were 170 moderately and severely mentally retarded men who were divided into two groups. The first group was used to formulate a new prediction equation and the second group was used to cross-validate and ascertain the stability of the derived equation. The prediction equation, employing waist and forearm circumferences, height and weight as predictors, and estimated percent body fat calculated by the generalized regression equation of Jackson and Pollock (1978) as the criterion measure, was formulated using a stepwise multiple regression analysis. A multiple R value of .86 was obtained for the derived equation with a standard error of estimate value of 3.35. The equation was cross-validated on the second sample to ascertain its stability. An r of .81 and a standard error of estimate of 4.41 was obtained between the subjects’ estimated percent body fat, using the new equation, and the criterion measure. This simplified equation provides practitioners with an accurate, reliable, and inexpensive method of estimating percent body fat for adult mentally retarded males.

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Phillip G. Post, Jeffrey T. Fairbrother, Joao A. C. Barros and J. D. Kulpa

Allowing self-control over various modes of instructional support has been shown to facilitate motor learning. Most research has examined factors that directly altered task-relevant information on a trial-to-trial basis (e.g., feedback). Recent research suggests that self-control (SC) effects extend to the manipulation of other types of factors (e.g., total number of practice trials completed). This research also illustrated that learners sometimes select a very small amount of practice when given latitude to do so. The purpose of the current study was to examine the effects of SC practice within a fixed time period on the learning of a basketball set shot. SC participants chose when to attempt each shot within two 15-min practice sessions, thereby controlling both the total number of shots taken and the spacing of shots. Yoked participants completed the same number of shots as their SC counterparts. Spacing of shots was also matched across groups. The SC group was more accurate and had higher form scores and longer preshot times during retention. These findings provided additional support for the generalizability of SC effects and extended prior research, showing that autonomy over total practice duration was not a prerequisite for the observed effects.

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Ryan D. Burns, Timothy A. Brusseau, Yi Fang, You Fu and James C. Hannon

Purpose:

The purpose of this study was to examine the relationships among waist-to-height ratio (WHtR), aerobic fitness, and cardio-metabolic risk factors in Hispanic children from low-income U.S. schools.

Method:

Participants were 198 Hispanic children from low-income schools (Mean age = 10.3 ± 0.5 years; 119 girls, 79 boys). Waist circumference, height, and cardio-metabolic blood markers were collected in a fasted state. Estimated VO2 Peak scores were also collected. Multilevel generalized mixed effects models were employed to examine the independent effect of WHtR and aerobic fitness classification on a child meeting recommended levels for each cardio-metabolic blood marker.

Results:

A child having a WHtR < 0.5 related to meeting recommended levels for HDL cholesterol (OR = 3.25, p < .01), triglycerides (OR = 2.94, p < .01), glucose (OR = 3.42, p < .01), and related to a lower continuous Mean Arterial Pressure (MAP) score (β = −8.5 mmHg, p < .01). Aerobic fitness classification only independently related to meeting recommended levels for HDL cholesterol (OR = 2.94, p = .010).

Conclusion:

Having a WHtR < 0.5 independently associated with favorable cardio-metabolic blood markers and thus serves as an effective screening tool for cardio-metabolic risk in Hispanic children from low-income schools.

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Gavin R. McCormack, Billie Giles-Corti and Max Bulsara

Background:

This study examines the relationships between the availability and use of recreational destinations and physical activity.

Methods:

Analysis included n = 1355 respondents. Associations between the density of free and pay-for-use recreational destinations, demographics, and use of free and pay-for-use recreational destinations within the neighborhood were examined, followed by associations with sufficient moderate and vigorous physical activity using generalized estimating equations.

Results:

The likelihood of using a local pay recreational destination increased for each additional local pay facility (OR 1.51, 95% CI 1.32 to 1.73) and was lower for those with motor vehicle access (OR 0.51, 95% CI 0.26 to 0.99). The likelihood of using a local free destination increased for each additional local free facility (OR 1.12, 95% CI 1.02 to 1.20) and was higher among women (OR 1.64, 95% CI 1.11 to 2.44). Destination use was associated with both moderate and vigorous-intensity physical activity.

Conclusions:

Increasing the density of neighborhood recreational destinations is associated with the use of facilities and participation in sufficient levels of physical activity.

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Yi-nam Suen, Ester Cerin, Anthony Barnett, Wendy Y.J. Huang and Robin R. Mellecker

Background:

Valid instruments of parenting practices related to children’s physical activity (PA) are essential to understand how parents affect preschoolers’ PA. This study developed and validated a questionnaire of PA-related parenting practices for Chinese-speaking parents of preschoolers in Hong Kong.

Methods:

Parents (n = 394) completed a questionnaire developed using findings from formative qualitative research and literature searches. Test-retest reliability was determined on a subsample (n = 61). Factorial validity was assessed using confirmatory factor analysis. Subscale internal consistency was determined.

Results:

The scale of parenting practices encouraging PA comprised 2 latent factors: Modeling, structure and participatory engagement in PA (23 items), and Provision of appropriate places for child’s PA (4 items). The scale of parenting practices discouraging PA scale encompassed 4 latent factors: Safety concern/overprotection (6 items), Psychological/behavioral control (5 items), Promoting inactivity (4 items), and Promoting screen time (2 items). Test-retest reliabilities were moderate to excellent (0.58 to 0.82), and internal subscale reliabilities were acceptable (0.63 to 0.89).

Conclusion:

We developed a theory-based questionnaire for assessing PA-related parenting practices among Chinese-speaking parents of Hong Kong preschoolers. While some items were context and culture specific, many were similar to those previously found in other populations, indicating a degree of construct generalizability across cultures.

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Cecilie Thøgersen-Ntoumani, Elizabeth Loughren, Joan Duda and Kenneth Richard Fox

Background:

A 16-week lunchtime walking intervention was designed to increase physical activity in physically inactive University employees. The program was delivered and monitored twice over 7 months to examine feasibility across different seasons.

Methods:

Seventy-five participants (n = 69 females, n = 6 males; mean age = 47.68) were randomly allocated into a Winter (February start) or Spring group (May start). Participants were asked to complete 3 weekday lunchtime walks and 2 weekend walks. Weeks 1 to 10 were led by walk leaders (group phase) while the participants self-organized their walks during weeks 11 to 16 (independent phase). Yamax pedometers recorded daily step counts and walk group leaders recorded participant attendance in the group phase. Acceptability was assessed via a satisfaction survey and 2 focus groups with participants.

Results:

A participant pool representative by ethnicity, but not gender was recruited using a range of strategies. The program demonstrated good retention across both groups (73%). The intervention was acceptable to participants. More steps were accumulated in the group-led versus the independent phase.

Conclusion:

The intervention is feasible in this workplace setting across different seasonal periods. In the future, researchers should examine if the findings can be replicated in a definitive trial and generalize to other workplace settings.