Mechanical and Biomedical Engineering Faculty Publications and Presentations Copyright (c) 2013 Boise State University All rights reserved. http://scholarworks.boisestate.edu/mecheng_facpubs Recent documents in Mechanical and Biomedical Engineering Faculty Publications and Presentations en-us Fri, 24 May 2013 12:02:03 PDT 3600 Stochastic Reconstruction of Multiple Source Atmospheric Contaminant Dispersion Events http://scholarworks.boisestate.edu/mecheng_facpubs/42 http://scholarworks.boisestate.edu/mecheng_facpubs/42 Fri, 22 Mar 2013 11:57:58 PDT Reconstruction of intentional or accidental release of contaminants into the atmosphere using concentration measurements from a sensor network constitutes an inverse problem. An added complexity arises when the contaminant is released from multiple sources. Determining the correct number of sources is critical because an incorrect estimation could mislead and delay response efforts. We present a Bayesian inference method coupled with a composite ranking system to reconstruct multiple source contaminant release events. Our approach uses a multi-source data-driven Gaussian plume model as the forward model to predict the concentrations at sensor locations. Bayesian inference with Markov chain Monte Carlo (MCMC) sampling is then used to infer model parameters within minutes on a conventional processor. The composite ranking system enables the estimation of the number of sources involved in a release event. The ranking formula allows plume model results to be evaluated based on a combination of error (scatter), bias, and correlation components. We use the 2007 FUSION Field Trial concentration data resulting from near-ground-level sources to test the multi-source event reconstruction tool (MERT). We demonstrate successful reconstructions of source parameters, as well as the number of sources involved in a release event with as many as three sources.

]]> Derek Wade et al. Multi-Level Parallelism for Incompressible Flow Computations on GPU Clusters http://scholarworks.boisestate.edu/mecheng_facpubs/41 http://scholarworks.boisestate.edu/mecheng_facpubs/41 Fri, 07 Dec 2012 12:34:47 PST We investigate multi-level parallelism on GPU clusters with MPI-CUDA and hybrid MPI-OpenMP-CUDA parallel implementations, in which all computations are done on the GPU using CUDA. We explore efficiency and scalability of incompressible flow computations using up to 256 GPUs on a problem with approximately 17.2 billion cells. Our work addresses some of the unique issues faced when merging fine-grain parallelism on the GPU using CUDA with coarse-grain parallelism that use either MPI or MPI-OpenMP for communications. We present three different strategies to overlap computations with communications, and systematically assess their impact on parallel performance on two different GPU clusters. Our results for strong and weak scaling analysis of incompressible flow computations demonstrate that GPU clusters offer significant benefits for large data sets, and a dual-level MPI-CUDA implementation with maximum overlapping of computation and communication provides substantial benefits in performance. We also find that our tri-level MPI-OpenMP-CUDA parallel implementation does not offer a significant advantage in performance over the dual-level implementation on GPU clusters with two GPUs per node, but on clusters with higher GPU counts per node or with different domain decomposition strategies a tri-level implementation may exhibit higher efficiency than a dual-level implementation and needs to be investigated further.

]]> Dana A. Jacobsen et al. Kinematic and Kinetic Synergies of the Lower Extremities During the Pull in Olympic Weightlifting http://scholarworks.boisestate.edu/mecheng_facpubs/40 http://scholarworks.boisestate.edu/mecheng_facpubs/40 Fri, 07 Sep 2012 10:52:16 PDT The purpose of this study was to identify multijoint lower extremity kinematic and kinetic synergies in weightlifting and compare these synergies between joints and across different external loads. Subjects completed sets of the clean exercise at loads equal to 65, 75, and 85% of their estimated 1-RM. Functional data analysis was used to extract principal component functions (PCF's) for hip, knee, and ankle joint angles and moments of force during the pull phase of the clean at all loads. The PCF scores were then compared between joints and across loads to determine how much of each PCF was present at each joint and how it differed across loads. The analyses extracted two kinematic and four kinetic PCF's. The statistical comparisons indicated that all kinematic and two of the four kinetic PCF's did not differ across load, but scaled according to joint function. The PCF's captured a set of joint- and load-specific synergies that quantified biomechanical function of the lower extremity during Olympic weightlifting and revealed important technical characteristics that should be considered in sports training and future research.

]]> Kristof Kipp et al. Weightlifting Performance is Related to Kinematic and Kinetic Patterns of the Hip and Knee Joints http://scholarworks.boisestate.edu/mecheng_facpubs/39 http://scholarworks.boisestate.edu/mecheng_facpubs/39 Fri, 10 Aug 2012 13:05:14 PDT The purpose of this study was to investigate correlations between biomechanical outcome measures and weightlifting performance. Joint kinematics and kinetics of the hip, knee, and ankle were calculated while ten subjects performed a clean at 85% of 1-RM. Kinematic and kinetic time-series patterns were extracted with principal components analysis. Discrete scores for each time-series pattern were calculated and used to determine how each pattern was related to body-mass normalized 1-RM. Two hip kinematic and two knee kinetic patterns were significantly correlated with relative 1-RM. The kinematic patterns captured hip and trunk motions during the first pull and hip joint motion during the movement transition between the first and second pull. The first kinetic pattern captured a peak in the knee extension moment during the second pull. The second kinetic pattern captured a spatiotemporal shift in the timing and amplitude of the peak knee extension moment. The kinematic results suggest that greater lift mass was associated with steady trunk position during the first pull and less hip extension motion during the second-knee bend transition. Further, the kinetic results suggest that greater lift mass was associated with a smaller knee extensor moments during the first pull, but greater knee extension moments during the second pull, as well as an earlier temporal transition between knee flexion-extension moments at the beginning of the second pull. Collectively, these results highlight the importance of controlled trunk and hip motions during the first pull and rapid employment of the knee extensor muscles during the second pull in relation to weightlifting performance.

]]> Kristof Kipp et al. Large Eddy Simulations of Turbulent Incompressible Flows on GPU Clusters http://scholarworks.boisestate.edu/mecheng_facpubs/38 http://scholarworks.boisestate.edu/mecheng_facpubs/38 Thu, 05 Apr 2012 12:59:28 PDT Graphics processing unit (GPU) and clusters of GPUs have emerged as cost-effective general-purpose scientific computing platforms that can substantially accelerate simulation science applications. Over the last four years, we have developed a parallel incompressible flow solver with an amalgamated geometric multigrid method. The flow solver uses MPI for coarse-grain and CUDA for fine-grain parallelism, while overlapping communication with computations. We have tested our flow solver for scalability on the NCSA Lincoln and TACC Longhorn GPU clusters, and demonstrated the importance of overlapping communication with computations and network bandwidth on emerging GPU clusters. In this study we extend our flow solver to perform large-eddy simulations of turbulent flows in a channel with friction Reynolds number of 395. Our results agree well with published direct numerical simulation results and demonstrate that GPU clusters can be an effective tool in fundamental turbulence research.

]]> Rey DeLeon et al. GPU-Accelerated Large-Eddy Simulation of Turbulent Channel Flows http://scholarworks.boisestate.edu/mecheng_facpubs/37 http://scholarworks.boisestate.edu/mecheng_facpubs/37 Wed, 29 Feb 2012 12:55:27 PST High performance computing clusters that are augmented with cost and power efficient graphics processing unit (GPU) provide new opportunities to broaden the use of large-eddy simulation technique to study high Reynolds number turbulent flows in fluids engineering applications. In this paper, we extend our earlier work on multi-GPU acceleration of an incompressible Navier-Stokes solver to include a large-eddy simulation (LES) capability. In particular, we implement the Lagrangian dynamic subgrid scale model and compare our results against existing direct numerical simulation (DNS) data of a turbulent channel flow at Reτ = 180. Overall, our LES results match fairly well with the DNS data. Our results show that the Reτ = 180 case can be entirely simulated on a single GPU, whereas higher Reynolds cases can benefit from a GPU cluster.

]]> Rey DeLeon et al. The Party’s Over: Sustaining Support Programs When the Funding is Done http://scholarworks.boisestate.edu/mecheng_facpubs/36 http://scholarworks.boisestate.edu/mecheng_facpubs/36 Wed, 08 Feb 2012 14:13:01 PST In the lifecycle of an engineering education grant, the phase where best practices are sustained and disseminated is perhaps the most crucial stage for maximizing impact. Yet this transition phase often receives the least attention as project team enthusiasm can wane, while funding tapers off, and faculty priorities are pulled in other directions. There are numerous obstacles associated with sustaining program changes, even those perceived as very valuable. Typical challenges are: What happens when the funding runs out? What grant-developed programs should be sustained by the university? Does the institution need to internally allocate resources in an annual budget large enough to replace the grant?

Ultimately, sustaining successful programmatic improvements is about “change management” in an institution. In this paper, we will review the literature relating to institutional change in engineering education. We will build on current curriculum change models, in the context of a major engineering education grant at Boise State University that included a variety of curricular enhancements, academic support, and outreach efforts. Over the past two years, the project team focused considerable effort on institutionalizing the most successful programs, and met with mixed results. While many programs will continue and benefit students long-term, other programs, even ones with stellar success and solid assessment, have not been entirely adopted for a number of reasons that we will examine. We will review the role assessment played in the process of program transfer (from the grant to the university) and lessons learned about building alliances with other campus partners to achieve university-level buy-in, well before the last stage of the grant. Finally, we will discuss two factors that are not identified in institutional change literature, but that contributed significantly to the successful transition of our programs—the importance of taking a research based approach, and flexibility in time and resource allocation.

]]> John Gardner et al. Creating and Implementing Cloud-Based Simulations to Enhance a Multivariable Calculus Course http://scholarworks.boisestate.edu/mecheng_facpubs/35 http://scholarworks.boisestate.edu/mecheng_facpubs/35 Thu, 01 Dec 2011 15:45:30 PST A Cloud resource at Boise State University was used to enhance a large section of Multivariable and Vector Calculus (MATH 275) taken by engineering majors. This section was developed to deal with rapidly-increasing engineering enrollment. Our hypothesis was that curricula could be successfully delivered to a very large class (120 students) by augmenting instruction with Cloud resources and Clicker technology. Interactive exercises, hosted on the Cloud, were assigned instead of traditional textbased homework. Exercises were developed by a team of faculty and graduate students funded by a Hewlett-Packard Labs grant[1]. Exercises were created using MATLAB [2] and Working Model[3] software. Student satisfaction and perception of learning were measured using Clicker-based surveys associated with each exercise. Cloud computing resources hosted on university workstations provide access to licensed software used by STEM students. University students access our cloud resource using the same user id's and passwords that they use to access other University resources. Remote Graphics Software (RGS)[4], available from Hewlett-Packard, enables students to remotely access any software made available to them on the cloud. Moreover, RGS enables the students to work together on the same file. Finally, RGS Sender software enables the host computer to do most of the video processing, so that the remote user can run graphics-intensive software using a low-end PC or thin client without performance impairment. The cloud was hosted on 16 Blade workstations provided by a Hewlett-Packard Innovations in Engineering (IOE) award[5]. Providing easy access to our cloud resource was fundamental in achieving our goals. We developed a rubric for accessing and using our cloud resource. Clicker surveys conducted during classes at the beginning, middle, and end of the semester provided data elucidating student opinions on accessing and using the cloud resource. Comments were also elicited during the end of semester course evaluation. Results showed students became more comfortable with the cloud resource as the semester progressed. Almost all of the students were comfortable with accessing and using the cloud resource by the end of the semester. Our template for providing cloud resources might be useful for others considering the implementation of cloud technology.

]]> Joseph Guarino et al. Acceleration of Complex Terrain Wind Predictions Using Many-Core Computing Hardware http://scholarworks.boisestate.edu/mecheng_facpubs/34 http://scholarworks.boisestate.edu/mecheng_facpubs/34 Mon, 21 Nov 2011 13:45:18 PST Advances in software and hardware technologies in many-core graphics processing units (GPU) create new opportunities to accelerate computational turn-around time of computational fluid dynamics (CFD) simulations for wind engineering applications, where rapid simulations can make a tremendous impact on the current practice. We investigate the computational performance of a GPU-accelerated incompressible Navier-Stokes solver for 3D flows (GIN3D) for complex terrain simulations on multi-GPU desktop platforms and on the recently deployed NCSA Lincoln Tesla Cluster. Our results demonstrate the potential of GPU computing to accelerate complex terrain wind forecasting applications.

]]> Inanc Senocak et al. Accelerating Incompressible Flow Computations with a Pthreads-CUDA Implementation on Small-Footprint Multi-GPU Platforms http://scholarworks.boisestate.edu/mecheng_facpubs/33 http://scholarworks.boisestate.edu/mecheng_facpubs/33 Mon, 21 Nov 2011 13:42:09 PST Graphics processor units (GPU) that are originally designed for graphics rendering have emerged as massively-parallel "co-processors" to the central processing unit (CPU). Small-footprint multi-GPU workstations with hundreds of processing elements can accelerate compute-intensive simulation science applications substantially. In this study, we describe the implementation of an incompressible flow Navier–Stokes solver for multi-GPU workstation platforms. A shared-memory parallel code with identical numerical methods is also developed for multi-core CPUs to provide a fair comparison between CPUs and GPUs. Specifically, we adopt NVIDIA’s Compute Unified Device Architecture (CUDA) programming model to implement the discretized form of the governing equations on a single GPU. Pthreads are then used to enable communication across multiple GPUs on a workstation. We use separate CUDA kernels to implement the projection algorithm to solve the incompressible fluid flow equations. Kernels are implemented on different memory spaces on the GPU depending on their arithmetic intensity. The memory hierarchy specific implementation produces significantly faster performance. We present a systematic analysis of speedup and scaling using two generations of NVIDIA GPU architectures and provide a comparison of single and double precision computational performance on the GPU. Using a quad-GPU platform for single precision computations, we observe two orders of magnitude speedup relative to a serial CPU implementation. Our results demonstrate that multi-GPU workstations can serve as a cost-effective small-footprint parallel computing platform to accelerate computational fluid dynamics (CFD) simulations substantially.

]]> Julien C. Thibault et al. Balancing Risks, Rewards of Athletic Shoe Traction http://scholarworks.boisestate.edu/mecheng_facpubs/32 http://scholarworks.boisestate.edu/mecheng_facpubs/32 Mon, 21 Nov 2011 13:35:45 PST Athletic shoes must provide at least enough traction to maximize performance and minimize slipping, but too much traction can potentially increase the risk of injury. Research suggests that traction on modern artificial turf can vary depending on cutting angle.

]]> Michelle B. Sabick et al. The Fixable Suture Anchor Plate: A Mechanical Comparison to Other Devices Commonly Used for Tendon Anchorage to Bone During Rotator Cuff Repair Surgery http://scholarworks.boisestate.edu/mecheng_facpubs/31 http://scholarworks.boisestate.edu/mecheng_facpubs/31 Mon, 21 Nov 2011 13:30:54 PST Background: The fixable suture anchor plate is a new device that has been designed with the intention of improving anchorage-to-bone strength during tendon-to-bone repair in patients with compromised bone quality. In this in vitro study we compare the load-to-failure and mode-of-failure results of a fixable suture anchor plate to that of other devices that are commonly used during rotator cuff repair surgery, including: a buttress plate, metal suture anchors, bioabsorbable suture anchors, and suture through simple tunnels without any augmenting device. We hypothesized that the fixable suture anchor plate would provide higher load-to-failure measurements compared to the other devices.

Methods: Each device was implanted into solid rigid polyurethane foam blocks with densities representing varying degrees of osteoporosis, and then tested to failure. ANOVA and post-hoc analysis tests were used to determine statistical significance.

Results: The average load to failure for the fixable suture anchor plate was significantly greater in low and medium density blocks compared to the other devices tested (p≤0.01). The greatest difference in magnitude was seen in low density blocks (5pcf), where the fixable suture anchor plate failed at 278 ± 53 N (mean ± standard deviation), about double the value of the next highest failure at 133 ± 11 N for the buttress plate.

Conclusions: The fixable suture anchor plate demonstrated superior anchorage strength in low and medium density foam blocks compared to the other devices that were tested in this study. Further studies are needed to determine whether clinical use of a fixable suture anchor plate will translate into a higher rotator-cuff-repair success rate in vivo.

]]> C. Scott Humphrey et al. Effect of Probe Size on EMG Activity of the Wrist and Hand in Diagnostic Sonographers http://scholarworks.boisestate.edu/mecheng_facpubs/30 http://scholarworks.boisestate.edu/mecheng_facpubs/30 Mon, 21 Nov 2011 13:10:29 PST Medical sonography covers a broad spectrum of specialty areas including vascular sonography, cardiac sonography, and obstetric sonography. Because medical sonography covers such a broad array of clinical needs without the use of ionizing radiation, it has become essential in the diagnosis of many life-threatening diseases [1]. Although sonography is an indispensable tool, it is not without shortcomings. Every year more than 80% of clinical sonographers experience some form of musculoskeletal related pain, with up to 20% suffering from career ending injuries [1, 2]. These statistics make sonographers among the highest at risk groups for work-related musculoskeletal disorders (WRMSDs). Current research points to the poor ergonomics of the ultrasound transducer as the main factor in the cause of WRMSDs. The awkward upper extremity positions required, the repetitive nature of the movements and the static aspect of the transducer grip have all been implicated in the development of WRMSDs [3]. The purpose of this study was to quantify wrist range of motion and muscle activation during scanning using two different standard ultrasound transducers. The data will be used to inform design of more ergonomic ultrasound transducers.

]]> Seth M. Kuhlman et al. The Effect of Seat Position on Wheelchair Propulsion Biomechanics http://scholarworks.boisestate.edu/mecheng_facpubs/29 http://scholarworks.boisestate.edu/mecheng_facpubs/29 Mon, 21 Nov 2011 13:04:59 PST This study examined the effect of seat position on handrim biomechanics. Thirteen experienced users propelled a wheelchair over a smooth level floor at a self-selected speed. Kinetic and temporal-distance data were collected with the use of an instrumented rim and a motion analysis system. A custom-designed axle was used to change the seat position. We used repeated measures analysis of variance to evaluate if differences existed in the temporal-distance and kinetic data with change in seat position. Results showed that a shorter distance between the axle and shoulder (low seat height) improved the push time and push angle temporal variables (p < 0.0001). Tangential force output did not change with seat position. Axial and radial forces were highest in the lowest seat position (p < 0.001). Propulsion efficiency as measured by the fraction of effective force did not significantly change with seat position.

]]> Brian R. Kotajarvi et al. A New Method to Quantify Demand on the Upper Extremity During Manual Wheelchair Propulsion http://scholarworks.boisestate.edu/mecheng_facpubs/28 http://scholarworks.boisestate.edu/mecheng_facpubs/28 Mon, 21 Nov 2011 12:56:30 PST

Objective

To use an ergonomics-based rating that characterizes both demand on, and capacity of, upper-extremity muscle groups during wheelchair propulsion to help identify the muscle groups most at risk for pain or overuse injury in a relatively demanding wheelchair propulsion task.

Design

Case series.

Setting

Biomechanics research laboratory.

Participants

Sixteen manual wheelchair users with complete (American Spinal Injury Association grade A) T6-L2 paraplegia.

Interventions

Not applicable.

Main outcome measures

Internal peak joint moments required by each of the major upper-extremity muscle groups for propelling a wheelchair up a ramp; isometric strength of each of the muscle groups in positions simulating wheelchair propulsion; and wheelchair propulsion strength rating (WPSR) for each muscle group, calculated by normalizing the joint demands to their capacity.

Results

The largest joint moment was for shoulder flexion, at 39.7±13.9Nm. Shoulder flexion also accounted for the peak WPSR value of 66.5%±20.3%. Supination and pronation movements had low peak moment requirements (3.4Nm, 5.0Nm, respectively) but high WPSR values (41%, 53%, respectively).

Conclusions

Even a relatively benign ramp (2.9°) places a large demand on the musculature of the upper extremity, as assessed by using the WPSR to indicate muscular demand.

]]> Michelle B. Sabick et al. Humeral Torque in Professional Baseball Pitchers http://scholarworks.boisestate.edu/mecheng_facpubs/27 http://scholarworks.boisestate.edu/mecheng_facpubs/27 Mon, 21 Nov 2011 12:47:49 PST Background: Spontaneous fracture of the humeral shaft in throwers is a rare but well-known phenomenon. Although it has been hypothesized that the biomechanics of the throw cause such fractures, it is not clear how or when the fractures occur in the pitching motion.

Methods: The torque acting about the long axis of the humerus was calculated in 25 professional baseball pitchers throwing in game situations.

Results: Peak humeral axial torque reached a mean value of 92 ± 16 Nm near the time of maximum shoulder external rotation at the end of the cocking phase. This torque tended to externally rotate the distal end of the humerus relative to its proximal end. The direction of the torque was consistent with the external rotation spiral fractures of the humerus noted to occur in throwers. The magnitude of the peak humeral torque averaged 48% of the theoretical torsional strength of the humerus, suggesting that repetitive stress plays a role in humeral shaft fractures.

Conclusions: Fractures are most likely to occur near the time of maximum shoulder external rotation when humeral torque peaks. Pitchers whose elbows were more extended at stride foot contact tended to have lower peak humeral torques.

]]> Michelle B. Sabick et al. Valgus Torque in Youth Baseball Pitchers: A Biomechanical Study http://scholarworks.boisestate.edu/mecheng_facpubs/26 http://scholarworks.boisestate.edu/mecheng_facpubs/26 Mon, 21 Nov 2011 11:14:32 PST The purpose of this study was to determine the biomechanical and anthropometric factors contributing to elbow valgus torque during pitching. Video data of 14 youth pitchers throwing fastballs were used to calculate shoulder and elbow kinematics and kinetics. Peak elbow valgus torque averaged 18 Nm and occurred just before maximal shoulder external rotation. The magnitude of valgus torque was most closely correlated with the thrower's weight. When subject weight and height were controlled for, maximum shoulder abduction torque and maximum shoulder internal rotation torque were most strongly associated with elbow valgus torque, accounting for 85% of its variance (P < .001). When only kinematic variables were considered, maximum shoulder external rotation accounted for 33% of the variance in valgus torque. Given that the biomechanical variables correlated with peak valgus torque are not easily modifiable, limiting the number of innings pitched is likely the best way to reduce elbow injury in youth pitchers.

]]> Michelle B. Sabick et al. Modeling the Growth Plates in the Pediatric Knee: Implications for Anterior Cruciate Ligament Reconstruction http://scholarworks.boisestate.edu/mecheng_facpubs/25 http://scholarworks.boisestate.edu/mecheng_facpubs/25 Mon, 21 Nov 2011 11:10:17 PST The authors develop 3-D models of the pediatric knee from magnetic resonance imaging (MRI) image files, with the goal of minimizing injury to the pediatric growth plate during surgery. Computerized tomography (CT) scans have better resolution and contrast between bone and soft tissue than MRI scans; however, surgeons rely upon MRI scans to plan knee-joint surgeries such as anterior cruciate ligament (ACL) reconstruction. Surgeons can use the virtual models to plan and verify surgical procedures such as hole drilling and ligament attachments, and to determine volume removed from a growth plate due to different drill-hole placements with various drill sizes.

]]> Joseph Guarino et al. Biomechanics of the Shoulder in Youth Baseball Pitchers: Implications for the Development of Proximal Humeral Epiphysiolysis and Humeral Retrotorsion http://scholarworks.boisestate.edu/mecheng_facpubs/24 http://scholarworks.boisestate.edu/mecheng_facpubs/24 Mon, 21 Nov 2011 11:02:23 PST Background: The effects of repetitive throwing on the shoulders of developing athletes are not well understood because of the paucity of data describing the biomechanics of youth pitchers and the plasticity of the developing skeleton.

Hypothesis: The direction and magnitude of the stresses that exist at the proximal humeral physis during the fastball pitching motion are consistent with the development of proximal humeral epiphysiolysis (Little League shoulder) and/or humeral retro-torsion.

Study Design: Descriptive laboratory study.

Methods: A total of 14 elite youth baseball pitchers (mean age, 12.1 ± 0.4 years) were filmed from the front and dominant side while throwing fastballs in a simulated game. The net force and torque acting on the humerus throughout the throwing motion were calculated using standard biomechanical techniques.

Results: The external rotation torque about the long axis of the humerus reached a peak value of 17.7 ± 3.5 N·m (2.7% ± 0.3% body weight × height) just before maximum shoulder external rotation. A shoulder distraction force of 214.7 ± 47.2 N (49.8% ± 8.3% body weight) occurred at, or just after, ball release.

Conclusion: Shear stress arising from the high torque late in the arm-cocking phase is large enough to lead to deformation of the weak proximal humeral epiphyseal cartilage, causing either humeral retrotorsion or proximal humeral epiphysiolysis over time. The stresses generated by the external rotation torque are much greater than those caused by distraction forces generated during the pitching motion of youth baseball pitchers.

Clinical Relevance: The motion of throwing fastballs by youth baseball pitchers results in force components consistent with proposed mechanisms for 2 clinical entities.

]]> Michelle B. Sabick et al. The Effects of a Commercially Available Warm-Up Program on Landing Mechanics in Female Youth Soccer Players http://scholarworks.boisestate.edu/mecheng_facpubs/23 http://scholarworks.boisestate.edu/mecheng_facpubs/23 Mon, 21 Nov 2011 10:51:54 PST The purpose of this study was to examine lower extremity kinematics following implementation of the Sportsmetrics Warm-Up for Injury Prevention and Performance (WIPP) training program. The hypothesis was that there would be no difference in landing mechanics between 2 groups of female youth soccer players (9-11 years of age), with 1 group (Treatment) completing the 8-week-duration (2 days per week) WIPP program and the other serving as a Control group. We recruited 21 female youth soccer players. Treatment (n = 12) and Control (n = 9) groups were established. Using the Sportsmetrics Software for Analysis of Jumping Mechanics, we analyzed lower extremity movement during landing after subjects jumped off a 30.5-cm box and immediately went into a vertical jump. No significant changes in knee separation values were observed in the Treatment group after 8 weeks of WIPP training. The results indicate that 8 weeks of WIPP training did not significantly alter landing strategies.

]]> Sara L. Grandstrand et al.