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Yu-Jen Chen and Christopher M. Powers

The purpose of this study was to determine if persons with patellofemoral pain (PFP) exhibit differences in patellofemoral joint reaction forces (PFJRFs) during functional activities. Forty females (20 PFP, 20 controls) underwent two phases of data collection: (1) magnetic resonance imaging (MRI) and (2) biomechanical analysis during walking, running, stair ascent, and stair descent. A previously described three-dimensional model was used to estimate PFJRFs. Resultant PFJRFs and the orthogonal components were reported. The PFP group demonstrated lower peak resultant PFJRFs and posterior component and superior component of the PFJRFs compared with the control group across all conditions. However, the PFP group had a higher peak lateral component of the PFJRF in three out of the four conditions evaluated. The lower resultant PFJRFs suggested that individuals with PFP may employ strategies to minimize patellofemoral joint loading, but it did not result in diminished lateral forces acting on the patella.

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Yu-Jen Chen, Irving Scher, and Christopher M. Powers

The purpose of this study was to describe an imaging based, subject specific model that was developed to quantify patellofemoral joint reaction forces (PFJRF’s). The secondary purpose was to test the model in a group of healthy individuals while performing various functional tasks. Twenty healthy subjects (10 males, 10 females) were recruited. All participants underwent two phases of data collection: 1) magnetic resonance imaging of the knee, patellofemoral joint, and thigh, and 2) kinematic, kinetic and EMG analysis during walking, running, stair ascent, and stair descent. Using data obtained from MRI, a subject specific representation of the extensor mechanism was created. Individual gait data were used to drive the model (via an optimization routine) and three-dimensional vasti muscle forces and subsequent three-dimensional PFJRF’s were computed. The average peak PFJRF was found to be highest during running (58.2 N/kg-bwt), followed by stair ascent (33.9 N/kg-bwt), stair descent (27.9 N/kg-bwt), and walking (10.1 N/kg-bwt). No differences were found between males and females. For all conditions, the direction of the PFJRF was always in the posterior, superior, and lateral directions. The posterior component of the PFJRF always had the greatest magnitude, followed by superior and lateral components. Our results indicate that estimates of the magnitude and direction of the PFJRF during functional tasks can be obtained using a 3D-imaging based model.

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Feng-Tzu Chen, Su-Ru Chen, I-Hua Chu, Jen-Hao Liu, and Yu-Kai Chang

This study examines the effect of a 12-week multicomponent exercise intervention on metacognition among preadolescents with obesity. Seventy-five preadolescents were randomly assigned to either a multicomponent exercise group or a reading control group. An exercise intervention consisting of a jumping rope was utilized to develop multifaceted fitness features, with each session lasting for 75 min and three sessions being conducted per week for 12 weeks. Results revealed significant interactions between group and time point for cardiovascular fitness, muscular endurance, flexibility, and power, as well as for Tower of London task measures, including total move score, total executive time, and total planning-solving time, with better postintervention performances achieved by the exercise group. Positive correlations between the physical fitness and metacognition measurements were also observed. These findings suggest that the multicomponent exercise benefits metacognition in obese preadolescents, with exercise-associated changes in multifaceted fitness features mediating the relationship between exercise and metacognition.