A MISSING LINK FOR AN EFFECTIVE REHABILITATION

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The effects of whole body vibration on the neuromuscular system

Recently, changes in human performance following whole-body vibration (WBV) training have been attributed to enhanced neuromuscular function. However, the exact neural and muscular mechanisms responsible for these changes remain less understood. The purpose of this study was to evaluate the acute and chronic effects of whole body vibration on the neural control of movement and muscle performance. Twenty male and female subjects with no history of leg injury were randomly assigned to either an experimental or control group. To assess the acute effects of WBV, data was collected from subjects immediately before and following an exposure to WBV (3 bouts of 2 minute with one minute rest between bouts). During the vibration exposure, subjects stood quietly on the platform with a slight amount of knee flexion. Subjects in the control group performed trials of quiet standing on the laboratory floor. Trial length, rest periods and body positions were identical for both groups. The variables used to evaluate the acute effects were electromechanical delay and rate of force development. To assess the chronic effects, the experimental group received WBV training in the laboratory over the course of 4 weeks. The training consisted of 3 sessions per week. During each session, the subjects performed 3 standing trials (2 minutes with one minute rest between bouts). The control group also reported to the laboratory for training consisting of trials of quiet standing. EMD and RFD were also used to assess chronic changes as well as two other measures on neural control, specifically presynaptic inhibition. The two measures of presynaptic inhibition were extrinsic presynaptic inhibition (EPI) and intrinsic presynaptic inhibition measured by paired reflex depression (PRD). The analysis for an acute effect consisted of a 2×2 (Group × Test) ANOVA for the dependent measures EMD and RFD. The experimental (WBV) group demonstrated a significant group × test interaction for the electromechanical delay (p=0.02) and rate of force development (p=0.03). The experimental group decreased EMD by 16% (from 23.42 ms to 19.3 ms) and increased RFD by 15.6% (from 274N/sec to 323 N/sec). The analysis for the chronic effect consisted of 2×3×2 (Group × Test × Time) repeated measure ANOVAs for the dependent measures (EMD, RFD, EPI, and PRD). After a 4 week of WBV training, the experimental (WBV) group demonstrated a significant decrease in electromechanical delay (EMD). The results also showed a significant group × test interaction for the rate of force development (RFD), and paired reflex depression (PRD) over the course of the study. There were no changes in extrinsic presynaptic inhibition noted in any of the comparisons. Through the use of these techniques and procedures, it is concluded that acute WBV has an effect on the EMD and RFD of the soleus muscle in young healthy subjects. Regarding chronic effects of WBV, our findings suggest that 4 weeks of WBV affects intrinsic presynaptic inhibition as measured by paired reflex depression as well as well as EMD and RFD

Sensorless Control of Surface-Mount Permanent-Magnet Synchronous Motors Based on a Nonlinear Observer

International audienceA nonlinear observer for surface-mount permanent-magnet synchronous motors (SPMSMs) was recently proposed by Ortega et al.(LSS, Gif-sur-Yvette Cedex, France, LSS Internal Rep., Jan. 2009). The nonlinear observer generates the position estimate hat(theta) via the estimates of sin theta and cos theta. In contrast to Luenberger-type observers, it does not require speed information, thus eliminating the complexity associated with speed estimation errors. Further, it is simple to implement. In this study, the nonlinear observer performance is verified experimentally. To obtain speed estimates from the position information, a proportional-integral (PI) tracking controller speed estimator was utilized. The results are good with and without loads, above 10 r/min

A STUDY ON THE CORRELATION BETWEEN THE FOOT FEATURES AND GAIT CHARACTERISTICS DURING OVER-GROUND WALKING

We analysed the correlation between the foot features such as foot length, foot width, the height and angles of foot arch curves and gait spatiotemporal parameters. To measure the structure of the foot, we measured the height and structural variation of medial longitudinal arch(MLA) and lateral longitudinal arch(LLA) in various conditions using a �� Scanning stage�� consisting of a single depth camera and four uni-axial force sensors. The gait spatiotemporal parameters were obtained by a motion capture system from the seventeen subjects. All subjects were instructed to walk at a regular pace, and spatiotemporal gait parameters of ten strides in the middle of the walkway were measured. As a result, it has been shown that the height angle of MLA is significantly correlated with gait temporal parameters while the LLA is significantly related to gait spatial parameters

A MACHINE-LEARNING-BASED GAIT ESTIMATION FROM THE FOOT ARCH PARAMETERS MEASURED BY A FOOT SCANNING SYSTEM

The purpose of this study is to develop a machine-learning-based regressor to estimate the gait-related parameters from the foot characteristics extracted by a foot scanning system. A fully-connected feed-forward neural network model was used to predict the gait parameters. The inputs of the model were the foot arch features and body anthropometric data, while the outputs of the model were the spatiotemporal gait parameters of the regular walking. The performance of the model was verified showing the accuracy of 95% or higher confirming the facts that foot features are dominant factors to estimate personalized gait patterns. In conclusion, the gait pattern can be easily assessed by measuring the foot depth-image from the foot scanner without using complex and expensive traditional methods if the data pools are significantly increased

Effects of Short-Rest Interval Time on Resisted Sprint Performance and Sprint Mechanical Variables in Elite Youth Soccer Players

This study explored the impact of short rest intervals on resisted sprint training in elite youth soccer players, specifically targeting enhanced initial-phase explosive acceleration without altering sprint mechanics. Fifteen U19 soccer players participated in a randomized crossover design trial, executing two sprint conditions: RST2M (6 sprints of 20 m resisted sprints with 2 min rest intervals) and RST40S (6 sprints of 20 m resisted sprints with 40 s rest intervals), both under a load equivalent to 30% of sprint velocity decrement using a resistance device. To gauge neuromuscular fatigue, countermovement jumps were performed before and after each session, and the fatigue index along with sprint decrement percentage were calculated. Interestingly, the results indicated no significant differences in sprint performance or mechanical variables between RST2M and RST40S, suggesting that the duration of rest intervals did not affect the outcomes. Horizontal resistance appeared to mitigate compensatory patterns typically induced by fatigue in short rest periods, maintaining effective joint movement and hip extensor recruitment necessary for producing horizontal ground forces. These findings propose a novel training strategy that could simultaneously enhance sprint mechanics during initial accelerations and repeated sprint abilities for elite youth soccer players—a methodology not previously employe

The Origin of Selective Adsorption of CO2 on Merlinoite Zeolites

Herein, we describe the CO2 adsorption behavior at 25‐75 °C and 0−1.0 bar of various alkali cation‐exchanged forms of merlinoite (framework type MER) zeolites with Si/Al = 2.3 and 3.8. The adsorption isotherms at 25 °C on the Na+ , K+ , Rb+ , and Cs+ forms of MER zeolite with Si/Al = 2.3 are characterized by a clear step, the CO2 pressure of which differs notably according to the type of their extraframework cations. Structural analysis shows that CO2 adsorption on the former three zeolites includes the relocation of gating cations with high site occupancy and the remarkable concomitant structural breathing. We define this unusual adsorption phenomenon as a cooperative cation gating‐breathing mechanism. The overall results suggest that the actual mechanism of selective CO2 adsorption on intermediate‐silica small‐pore zeolites can change from cation gating to cooperative cation gating‐breathing to breathing, depending on a combination of their topological and compositional (framework Al content and extraframework cation type and concentration) flexibilities.11Nsciescopu

Nanocrystalline Ag-ZK-5 zeolite for selective CH4/N2 separation

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