KINEMATIC AND KINETIC PATTERNS IN OLYMPIC WEIGHTLIFTING

The purpose of this study was to identify lower extremity kinematic and kinetic patterns during weightlifting movements and to compare them across different external loads. Subjects completed multiple sets of the clean exercise at various percentage loads. Principal component analysis (PCA) was used to extract kinematic and kinetics patterns of the hip, knee, and ankle joint across the loads. These patterns were then compared across joint and percentage load. Results indicate that lower extremity kinematics and kinetics can be characterized through combinations of PCA-derived patterns. Patterns differed predominantly between joints, but not across percentage loads. The results point to joint-specific lower extremity function during Olympic weightlifting and quantified important technical aspects

Effect of Loading Condition on Traction Coefficient Between Shoes and Artificial Turf Surfaces

Background. The interaction between a shoe and a turf surface is highly complex and difficult to characterize. Over the three decades since artificial turf was introduced, researchers have attempted to understand the traction caused by the interaction. However, some of the methodologies used for traction measurements have not capitalized on advances in currently available technology for testing and most testing conditions have not simulated realistic physiological loads. Method of Approach. To assess the effect of test condition on traction results, the newly designed TurfBuster testing device was used to collect traction data on FieldTurf™ brand artificial turf under varying conditions. Four cleated athletic shoes were tested under eight different vertical loads ranging from 222-1780 N. The static, dynamic, and peak traction coefficient values were calculated and averaged over three trials for each shoe and condition. Results. In all but the lowest vertical load condition, the static traction coefficient was less than the dynamic traction coefficient. There was a distinct separation found between 666 N and 888 N loading conditions for all three variables measured. Below the load condition of 666 N only one significant difference was found in all comparisons across and within shoe styles. Above 888 N multiple differences were found across shoe styles, but differences were not found within a shoe style until a load of at least 1554 N. Conclusions. At loads below 666 N the cleats perform almost identically at all three variables measured, static, dynamic, and peak traction coefficients. At loads above 888 N, shoe traction was different among the cleat styles for all traction variables. However, at loads between 888 N and 1334 N there were no differences found within a shoe style. This implies that each shoe has no performance difference in loads representative of up to one bodyweight. Due to these results the measurement of traction characteristics between cleated shoes and FieldTurf should be conducted at a load of at least 888 N to determine differences across shoe styles and loads ranging from 888 N to at least 1554 N to determine individual shoe characteristics

Effect of Probe Size on EMG Activity of the Wrist and Hand in Diagnostic Sonographers

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

Balancing Risks, Rewards of Athletic Shoe Traction

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

The Fixable Suture Anchor Plate: A Mechanical Comparison to Other Devices Commonly Used for Tendon Anchorage to Bone During Rotator Cuff Repair Surgery

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

Glenohumeral Muscle Activation During Provocative Tests Designed to Diagnose Superior Labrum Anterior-Posterior Lesions

Background: Despite considerable medical advances, arthroscopy remains the only definitive means of superior labrum anterior-posterior (SLAP) lesion diagnosis. Natural shoulder anatomic variants limit the reliability of radiographic findings and clinical evaluations are not consistent. Accurate clinical diagnostic techniques would be advantageous because of the invasiveness, patient risk, and financial cost associated with arthroscopy. Purpose: The purpose of this study was to examine the behavior of the joint-stabilizing muscles in provocative tests for SLAP lesions. Electromyography was used to characterize the muscle behavior, with particular interest in the long head of the biceps brachii (LHBB), as activation of the long head and subsequent tension in the biceps tendon should, based on related research, elicit labral symptoms in SLAP lesion patients. Study Design: Controlled laboratory study. Methods: Volunteers (N = 21) without a history of shoulder injury were recruited. The tests analyzed were active compression, Speed’s, pronated load, biceps load I, biceps load II, resisted supination external rotation, and Yergason’s. Tests were performed with a dynamometer to improve reproducibility. Muscle activity was recorded for the long and short heads of the biceps brachii, anterior deltoid, pectoralis major, latissimus dorsi, infraspinatus, and supraspinatus. Muscle behavior for each test was characterized by peak activation and proportion of muscle activity. Results: Speed’s, active compression palm-up, bicep I, and bicep II produced higher long head activations. Resisted supination external rotation, bicep I, bicep II, and Yergason’s produced a higher LHBB proportion. Conclusion: Biceps load I and biceps load II elicited promising long head behavior (high activation and selectivity). Speed’s and active compression palm up elicited higher activation of the LHBB, and resisted supination and Yergason’s elicited selective LHBB activity. These top performing tests utilize a unique range of test variables that may prove valuable for optimal SLAP test design and performance. Clinical Relevance: This study examines several provocative tests that are frequently used in the clinical setting as a means of evaluating a potential SLAP lesion