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Peng Zhang, Phillip Ward, Weidong Li, Sue Sutherland and Jackie Goodway

The purpose of this study was to examine the effects of Play Practice (PP) instruction on the performance of table tennis skills. Fifty-six college students in four intact classes were taught by two instructors using PP and Skill-focused Instruction (SI). A nonequivalent control/comparison group experimental design with pre and post measures was used. Three separate ANOVAs with a repeated measure (time effect) were conducted to examine the effects of PP and SI for each of the three dependent variables: (a) forehand drive accuracy, (b) forehand attack, and (c) serve. Results demonstrated that both PP and SI conditions were effective in improving participants’ skills in forehand drive, forehand attack, and serving from pre- to posttest. However, PP was more effective in improving participants’ skills in forehand attack and serving from pre to post as compared with SI.

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Peng Zhang, Jung Eun Lee, David F. Stodden and Zan Gao

Background: The objective was to examine changes of children’s time spent in sedentary, light physical activity, moderate to vigorous physical activity (MVPA), and estimated energy expenditure (EE) rates during weekdays and weekends across 3 years. Methods: An initial sample of 261 children’s (mean age = 7.81 y) 5-day physical activity and EE were assessed annually via accelerometry across 3 years using repeated-measures multivariate analysis of variance. The outcome variables were time spent in sedentary, light physical activity, MVPA, and kilocalories per day for weekdays and weekends. Results: A significant decrease in MVPA and EE occurred during weekdays across the 3 years (P = .01). Only the second-year data demonstrated an increase (+2.49 min) in weekend MVPA (P = .04). Children’s sedentary time during weekdays increased significantly in years 1 and 2 (P = .01), yet significantly decreased in the third year (−44.31 min). Children’s sedentary time during weekends significantly decreased in the first year (−27.31 min), but increased in the following 2 years (P = .01). Children’s light physical activity demonstrated a statistically significant increase in year 2 (+3.75 min) during weekdays (P = .05). Conclusions: Children’s MVPA and EE generally declined during weekdays but were maintained during weekends across a 3-year time span. Children may benefit most from weekday intervention strategies.

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Jason E. Hsu, Qiyu Peng, David A. Schafer, Jason L. Koh, Gordon W. Nuber and Li-Qun Zhang

The flexor-pronator mass is thought to be the primary dynamic valgus stabilizer of the elbow and protects the ulnar collateral ligament. However, in vivo multiaxis actions of individual muscles of the flexor-pronator group and their roles in valgus stability have not been investigated quantitatively. This study tested the hypothesis that individual muscles of the flexor-pronator muscle group produce a significant varus moment that provides elbow valgus stability. The flexor carpi ulnaris, flexor carpi radialis, and pronator teres were selectively activated, and the resulting multiaxis moments at the elbow measured at 0°, 30°, 60°, and 90° of elbow flexion using a six-axis force sensor were analyzed for their role in generating varus moment and protecting the ulnar collateral ligament. Considerable off-axis moments were generated by each muscle tested. Through the range of elbow flexion, the varus moment was the major component of the multiaxis action of the flexor carpi ulnaris (p < .001). The flexor carpi radialis and pronator teres had significant actions as elbow flexors and pronators (p ≤ .032); these muscles also had a significant varus contribution at 90° elbow flexion (p ≤.019). The results suggest that the flexor-pronator muscle group plays an important role in valgus stability of the elbow. In particular, the flexor carpi ulnaris creates a significant varus moment, which is important in unloading and protecting the ulnar collateral ligament. Rehabilitation and strengthening of the flexor-pronator muscle group may help prevent failure of the ulnar collateral ligament and may also help compensate for a medially insufficient elbow.