Effects of Foot Type on Multi-Segment Foot Motion in High- and Low-Arched Female Recreational Athletes

Introduction: Mal-alignment and dysfunction of the foot have been shown to result in an increased rate of injury and unique injury patterns. Aberrant foot function has been shown to contribute to repetitive stress and acute injuries. High-arched athletes have been shown to experience a greater rate of bony injury to the lateral aspect of the lower extremity while low-arched athletes experience greater rates of soft-tissue injury to the medial aspect of the lower extremity. Though foot type has been linked to these injury patterns, the mechanism by which these injury patterns occur remains unknown. Multi-segment foot models have been developed and allow for direct examination of motion within the foot. Therefore, the purpose of the current studies is to directly examine motion within the foot during vertical loading and dynamic loading tasks. Methods: Ten high- and 10 low-arched female athletes performed five trials in each of the following randomized conditions: walking, running, downward stepping, landing and a sit-to-stand exercise. Three-dimensional kinematics and ground reaction forces were collected simultaneously using a 7-camera motion capture system and force platform, respectively. Results: The HA athletes were less everted than the LA athletes in the ankle and mid-forefoot joints in all activities. The HA and LA athletes exhibited similar excursion values in all joints. Additionally, the HA athletes had a greater arch index and greater arch deformity during in the sit-to-stand task. Discussion and Conclusions: The HA athletes are less everted in all movements than the LA athletes; however excursion values were similar between the two groups. These data suggest the reason for different injury patterns within these two groups is not due to greater frontal plane ranges of motion. Furthermore, the sit-to-stand exercise showed that the HA athletes have a greater arch index but have greater deformation in response to a vertical load. The LA athletes exhibited less arch deformity but this deformity appears to be limited by the floor. The current study suggests the mechanism leading to different injury patterns in the HA and LA athletes is vertical compression of the arch

GREATER SKELETAL CONTRIBUTIONS TO LEG STIFFNESS IN HIGHCOMPARED TO LOW-ARCHED ATHLETES DURING RUNNING AND LANDING MOVEMENTS.

The contributions of skeletal and muscular structures to stiffness may underlie the distinct injury patterns observed in high- (HA) and low-arched (LA) athletes. This study compared skeletal and muscular contributions to leg stiffness in HA and LA athletes during running and landing. Ten HA and 10 LA female athletes performed five over ground running trials and five step off landing trials. Leg stiffness, and skeletal and muscular contributions to leg stiffness were calculated using Visual 3D and MatLab. HA athletes had greater leg stiffness (p=0.010) and skeletal stiffness (p=0.016) in running. During landing, HA had greater leg stiffness (p=0.015) and skeletal stiffness (p\u3c0.001) while LA athletes had greater muscular stiffness (p=0.025). These findings demonstrate that HA athletes place a greater reliance upon skeletal structures for load attenuation during running and landing which may underlie their distinct injury patterns

Dinitro­sylbis[tris­(4-chloro­phen­yl)phosphane]iron

The title dinitrosyl iron diphosphane complex, [Fe(NO)2(C18H12Cl3P)2] or Fe(NO)2 L 2 [L = P(C6H4-p-Cl)3] belongs to the family of metal dinitrosyl compounds with the general formula Fe(NO)2(L)x, referred to collectively as dinitrosyl iron compounds (DNICs). The iron atom is tetra­hedrally coordinated by two phosphane ligands and two NO groups with Fe—N—O bond angles of 178.76 (15) and 177.67 (14)°

Athletes Who Train on Unstable Compared to Stable Surfaces Exhibit Unique Postural Control Strategies in Response to Balance Perturbations

Background Athletes have been shown to exhibit better balance compared to non-athletes (NON). However, few studies have investigated how the surface on which athletes train affects the strategies adopted to maintain balance. Two distinct athlete groups who experience different types of sport-specific balance training are stable surface athletes (SSA) such as basketball players and those who train on unstable surfaces (USA) such as surfers. The purpose of this study was to investigate the effects of training surface on dynamic balance in athletes compared to NON. Methods Eight NON, eight SSA, and eight USA performed five 20-s trials in each of five experimental conditions including a static condition and four dynamic conditions in which the support surface translated in the anteroposterior (AP) or mediolateral (ML) planes using positive or negative feedback paradigms. Approximate entropy (ApEn) and root mean square distance (RMS) of the center of pressure (CoP) were calculated for the AP and ML directions. Four 3 × 5 (group × condition) repeated measures ANOVAs were used to determine significant effects of group and condition on variables of interest. Results USA exhibited smaller ApEn values than SSA in the AP signals while no significant differences were observed in the ML CoP signals. Generally, the negative feedback conditions were associated with significantly greater RMS values than the positive feedback conditions. Conclusion USA exhibit unique postural strategies compared to SSA. These unique strategies seemingly exhibit a direction-specific attribute and may be associated with divergent motor control strategies

A Comparison of Three Computer-based Methods Used to Determine EMG Signal Amplitude

Electromyography is a commonly used method to determine relative effort and neuromuscular drive to skeletal muscle. A limitation of the interpretation of EMG within the literature is the many methods used to determine the intensity of muscle activation. In the current study, ten healthy young adults performed a level walking task while EMG was recorded from the tibialis anterior, medial gastrocnemius and fibularis longus. The EMG data were rectified and smoothed using the root mean squared (RMS). Peak RMS (pRMS), mean RMS (mRMS) and integrated EMG (iEMG) were normalized to the peak value within the subject and were used to determine EMG amplitude. A 3x3 repeated measures analysis of variance was used to determine significant differences between the methods of determining EMG amplitude. The findings of the current study show that pRMS produced significantly lower EMG amplitudes than mRMS or iEMG values. Furthermore, mRMS and iEMG produced nearly identical normalized EMG amplitudes. Based on the findings of this study and the components of each measurement of EMG amplitude, it is suggested to use mRMS to determine EMG amplitude

Neuromuscular Adaptations in Elderly Adults Are Task-Specific during Stepping and Obstacle Clearance Tasks.

Elderly adults have a diminished movement capacity due to physiological and neurological declines associated with advancing age. Previous research suggests that elderly adults use altered neuromuscular patterns to conduct activities of daily living (ADLs). Limited research has addressed these altered activation strategies in obstacle clearance, stair ascent and stair descent. The purpose of this study was to compare neuromuscular activation patterns in young and elderly adults during these tasks. Eleven young and 10 healthy elderly adults performed five downward stepping, upward stepping and obstacle clearance trials. Surface EMG was measured from the quadriceps, hamstrings, gastrocnemius and tibialis anterior muscles. A 2x3 (group x condition) repeated measures analysis of variance was used to determine significant differences in muscle activation intensity. An apriori alpha level was set at p\u3c0.05. The results showed that elderly adults exhibited greater activation intensity than the young adults in all movement conditions. The significant differences in muscle activation intensity in the elderly adults were limited to the musculature driving the tested movement. The findings of the current study support previous research that elderly adults perform ADLs at a greater relative intensity than young adults. Furthermore, the current study shows that the disproportionate increase in muscle activation intensity is limited to the muscles that functionally drive the required task

Elementary forms and their dynamics: revisiting Mary Douglas

Mary Douglas's oeuvre furnishes the social sciences with one of the most profound and ambitious bodies of social theory ever to emerge from within anthropology. This article uses the occasion of the publication of Fardon's two volumes of her previously uncollected papers to restate her core arguments about the limited plurality of elementary forms of social organisation, about the institutional dynamics of conflict, and about conflict attenuation. In reviewing these two volumes, the article considers what those anthropologists who have been sceptical either of Douglas's importance or of the Durkheimian traditions generally, will want from these books to convince them to look afresh at her work. It concludes that the two collections will provide open-minded anthropologists with enough evidence of the creativity and significance of her achievement to encourage them to reopen her major theoretical works. An internal critique of some aspects of Douglas's handling of her arguments is offered, before the conclusion identifies the wider significance of her arguments for the social science

National trends in utilization, mortality, and survival after repair of type B aortic dissection in the Medicare population

ObjectiveThe application of thoracic endovascular aortic repair (TEVAR) has changed treatment paradigms for thoracic aortic disease. We sought to better define specific treatment patterns and outcomes for type B aortic dissection treated with TEVAR or open surgical repair (OSR).MethodsMedicare patients undergoing type B thoracic aortic dissection repair (2000-2010) were identified by use of a validated International Classification of Diseases, Ninth Revision diagnostic and procedural code–based algorithm. Trends in utilization were analyzed by procedure type (OSR vs TEVAR), and patterns in patient characteristics and outcomes were examined.ResultsTotal thoracic aortic dissection repairs increased by 21% between 2000 and 2010 (2.5 to 3 per 100,000 Medicare patients; P = .001). A concomitant increase in TEVAR was seen during the same interval (0.03 to 0.8 per 100,000; P < .001). By 2010, TEVAR represented 27% of all repairs. TEVAR patients had higher rates of comorbid congestive heart failure (12% vs 9%; P < .001), chronic obstructive pulmonary disease (17% vs 10%; P < .001), diabetes (8% vs 5%; P < .001), and chronic renal failure (8% vs 3%; P < .001) compared with OSR patients. For all repairs, patient comorbidity burden increased over time (mean Charlson comorbidity score of 0.79 in 2000, 1.10 in 2010; P = .04). During this same interval, in-hospital mortality rates declined from 47% to 23% (P < .001), a trend seen in both TEVAR and OSR patients. Whereas in-hospital mortality rates and 3-year survival were similar between patients selected for TEVAR and OSR, there was a trend toward women having slightly lower 3-year survival after TEVAR (60% women vs 63% men; P = .07).ConclusionsSurgical treatment of type B aortic dissection has increased over time, reflecting an increase in the utilization of TEVAR. Overall, type B dissection repairs are currently performed at lower mortality risk in patients with more comorbidities

Comparison of Ankle Taping and Bracing on Ankle Biomechanics during Landing in Functional Ankle Instability

Lateral ankle sprains are one of the most common injuries in athletics. Injury to lateral ankle ligaments can result in persistent instability of the ankle joint, known as functional ankle instability (FAI). Two methods of treating FAI are ankle taping and ankle bracing. The purpose of this study was to compare the effects of ankle taping and ankle bracing on ankle joint kinematics and kinetics during a landing task. Methods: Seven individuals with FAI and seven healthy controls performed three landing trials in each of three conditions: control, taped and braced. Ground reaction forces and three-dimensional kinematics were collected simultaneously while participants performed single-leg step-off landing trials from a box with a height of 0.6m. Peak ankle joint angles and moments were calculated using customized software. Results: Individuals with FAI produced significantly smaller inversion moments compared to healthy controls (p = 0.006). Ankle stabilization did not significantly alter ankle joint angles, ranges of motion or moments. Discussion: The present findings suggest that individuals with FAI exhibit unique ankle biomechanics independent of ankle stabilization modality. Future research may seek to investigate the multi-joint biomechanical adaptations associated with ankle stabilization in individuals with FAI compared to healthy controls