Pulling Phase Research Articles

Relationship of Kinematic Variables with the Performance of uprise on rings in Men’s Artistic Gymnastics

An investigationwas done to find the relation between selected kinematic variables and theperformance of uprise on rings in men’s artistic gymnastics.The study was conducted on national-levelgymnasts. The data on angular kinematic variables were collected on four different phases of uprise onrings. Linear kinematic variables were identifiedon two different phases of uprise on rings.The angular kinematic variables did not show any significant relationship at the 0.05 level at theDislocation Phase.Duringthe Vertical Line Cross Phasea significant relationship was found between angle atthe ankle andthe hipangle. InKicking and Pulling Phase angle at the left hip joint and the performance of Uprisehasshown a significant relationship.During the Supporting phase angle at the neck and the performance ofUprisewas showing a significant relationship, and also the angle of the left Wrist correlated significantlywith the angle of the Hip.Results also reveal that none of the linear kinematic variables at different Phases of Uprise showed anysignificant relationship at 0.05 level

Neuromuscular Assessment of a Stand-Up Paddle Stroke

This study analyzed muscle activity during the stand-up paddle stroke, considering the paddling side and the adjacent and opposing muscles relative to the position of the arms during paddling. Methods: Fourteen male paddleboarders performed three trials covering 195 m in which surface electromyography of the upper trapezius, biceps brachii, triceps brachii, tibialis anterior, and gastrocnemius medialis were recorded (four-cycle strokes on each side). The data were processed according to percentage of maximum voluntary contraction (% MVC). The MVC activation values (µV) for each muscle were then calculated and presented as percentage MVC (% MVC). Results: The recovery phase accounted for 60% of the paddle cycle, while the pull phase represented 39%. During right-side paddling, higher % MVC was found in the opposite-side upper trapezius (24.35%, p < 0.01) during the pulling phase and in the adjacent biceps brachii (8.36%, p < 0.03) during the recovery phase. In left-side paddling, greater % MVC was found in the opposite-side upper trapezius (27.60%, p < 0.01) during the pulling phase and in the opposite-side triceps brachii (42.25%, p < 0.04) during the recovery phase. Furthermore, the pulling phase exhibited higher MVC in the opposite-side upper trapezius compared to the recovery phase, both in the right-side (24.35%, p < 0.03) and left-side (27.60%, p < 0.01) paddling. Conclusions: these findings help establish the muscular activity of both sides of the paddling technique and the differences between the upper and lower limbs.

Shoulder and Neck Pain in Swimmers: Front Crawl Stroke Analysis, Correlation with the Symptomatology in 61 Masters Athletes and Short Literature Review.

Background: Swimming and, specifically, front crawl, can be included among the "overhead" sports. Overhead sports are a risk factor for some problems of the musculoskeletal system, especially the shoulder. The aim of this study was to assess the incidence of shoulder and neck pain in a Masters Swimming Team and its correlation with the crawl stroke. Methods: This is an observational study through video-analysis of the stroke and a questionnaire. The participants selected for the present study were 61 athletes of a Masters team, whose prevailing training stroke was the front crawl. Their stroke was analyzed during training using a go-pro camera mounted on a sliding trolley on a track, evaluating their technical defects with their trainer. A questionnaire about frequency of shoulder and neck pain during the last five years was administered to all the participants at the study. Results: From the questionnaire, 45 and 55 out of 61 athletes had suffered from shoulder pain and cervical pain, respectively. Both types of pain were correlated with the weekly swimming volume. The swimmers with hyperflexion of the wrist and prolonged internal rotation in the pulling phase had shoulder problems. Those who suffered from current shoulder pain reduced the underwater time. The four swimmers with an excessive body roll during breathing and those who kept their heads extended, reported cervical pain. Conclusions: Shoulder and neck pain could be prevented with the correction of specific technical errors in crawl stroke.

Changes in leg cycling muscle synergies after training augmented by functional electrical stimulation in subacute stroke survivors: a pilot study

BackgroundMuscle synergies analysis can provide a deep understanding of motor impairment after stroke and of changes after rehabilitation. In this study, the neuro-mechanical analysis of leg cycling was used to longitudinally investigate the motor recovery process coupled with cycling training augmented by Functional Electrical Stimulation (FES) in subacute stroke survivors.MethodsSubjects with ischemic subacute stroke participated in a 3-week training of FES-cycling with visual biofeedback plus usual care. Participants were evaluated before and after the intervention through clinical scales, gait spatio-temporal parameters derived from an instrumented mat, and a voluntary pedaling test. Biomechanical metrics (work produced by the two legs, mechanical effectiveness and symmetry indexes) and bilateral electromyography from 9 leg muscles were acquired during the voluntary pedaling test. To extract muscles synergies, the Weighted Nonnegative Matrix Factorization algorithm was applied to the normalized EMG envelopes. Synergy complexity was measured by the number of synergies required to explain more than 90% of the total variance of the normalized EMG envelopes and variance accounted for by one synergy. Regardless the inter-subject differences in the number of extracted synergies, 4 synergies were extracted from each patient and the cosine-similarity between patients and healthy weight vectors was computed.ResultsNine patients (median age of 75 years and median time post-stroke of 2 weeks) were recruited. Significant improvements in terms of clinical scales, gait parameters and work produced by the affected leg were obtained after training. Synergy complexity well correlated to the level of motor impairment at baseline, but it did not change after training. We found a significant improvement in the similarity of the synergy responsible of the knee flexion during the pulling phase of the pedaling cycle, which was the mostly compromised at baseline. This improvement may indicate the re-learning of a more physiological motor strategy.ConclusionsOur findings support the use of the neuro-mechanical analysis of cycling as a method to assess motor recovery after stroke, mainly in an early phase, when gait evaluation is not yet possible. The improvement in the modular coordination of pedaling correlated with the improvement in motor functions and walking ability achieved at the end of the intervention support the role of FES-cycling in enhancing motor re-learning after stroke but need to be confirmed in a controlled study with a larger sample size.Trial registrationClinicalTrial.gov, NCT02439515. Registered on May 8, 2015, .

Evaluation of the benefits in assisting cyclists to perform the pedal movement with real-time augmented feedback

Purpose of the study was to investigate the influence of training with augmented feedback of the pedal forces on performing the pedal movement on a bicycle ergometer. The aim was (1) to assist cyclists in optimizing their pedal technique and (2) to improve their perception of the execution of the pedal movement. 21 male sport students (28.1 ± 3.8 years), randomly divided in three groups: no feedback (nF), visual feedback (vF) and audiovisual feedback (avF), completed four tests in two training sessions. The Wattbike cycling ergometer measured pedal forces and provided them as vF or avF. Also the participants’ subjective perception was requested. All groups reduced the amplitudes of force and power output, with the avF group showing the greatest change. There were improvements in the overall shape of the pedal cycle with avF which is reflected in a rounder and more consistent shape, and balanced between each leg (strong pushing and balanced pulling phase). Individual statements underline the possibility of a quick modification of the pedal technique after two training sessions with feedback. Most of the participants in the avF group could imagine a general use of the sound in regular training for assistance.

Biased Estimation of Groundwater Velocity from a Push-Pull Tracer Test Due to Plume Density and Pumping Rate

The single-well push-pull tracer test is a convenient and cost-effective tool to estimate hydrogeological properties of a subsurface aquifer system. However, it has a limitation that test results can be affected by various experimental designs. In this study, a series of laboratory-scale push-pull tracer tests were conducted under various conditions controlling input tracer density, pumping rate, drift time, and hydraulic gradient. Based on the laboratory test results, numerical simulations were performed to evaluate the effects of density-induced plume sinking and pumping rate on the proper estimation of groundwater background linear velocity. Laboratory tests and numerical simulations indicated that the actual linear velocity was underestimated for the higher concentration of the input tracer because solute travel distance and direction during drift time were dominantly affected by the plume density. During the pulling phase, reasonable pumping rates were needed to extract the majority of injected tracer mass to obtain a genuine center of mass time (tcom). This study presents a graph showing reasonable pumping rates for different combinations of plume density and background groundwater velocity. The results indicate that careful consideration must be given to the design and interpretation of push-pull tracer tests.

A Compact X-Band Vector Network Analyzer for Microwave Image Sensing

This paper develops a compact and portable X-band vector network analyzer (VNA) for the low-cost microwave image sensing applications. Since significant local oscillator (LO) injection pulling and poor LO phase noise performance may reduce the accuracy of measurement, the developed VNA uses the single-conversion technique and the phase noise cancellation technique to suppress the injection pulling effect and the LO phase noise, respectively. A hybrid phase detection algorithm that includes arctangent, arcsine, and arccosine functions is proposed to overcome the bottleneck of the distortion of conventional quadrature phase detection in some phase regions. The experimental results demonstrate that the X-band microwave image sensing system that uses the developed VNA, which is highly compact and portable, can effectively yield a contour image of bones in a chicken wing and pork ribs.

Affective correlates of trichotillomania across the pulling cycle: Findings from an Italian sample of self-identified hair pullers.

Etiological models of trichotillomania (TTM) conceptualize hair pulling as a dysfunctional emotion regulation strategy; accordingly, some research has found that affective states change differentially across the hair pulling cycle. We explored emotional changes in a sample of Italian individuals reporting TTM. Eighty-nine participants reporting TTM completed a 12-item section of the Italian Hair Pulling Questionnaire online and rated the extent to which they had experienced 12 affective states before, during, and after hair pulling. Overall, participants reported increased levels of shame, sadness, and frustration from pre- to post-pulling, and decreased levels of calmness after hair pulling episodes. Moreover, participants reported increased pleasure and relief across the pulling cycle, and variations in the direction of change for anger and anxiety depending on the hair pulling phase. Lastly, reported boredom decreased across the hair pulling cycle. These findings highlight the importance of considering emotional changes experienced across the pulling cycle in Italian hair pullers.

Peculiarities of Activation of Human Muscles in Realization of Cyclic Bimanual Movements with Different Organization of the Cycles

According to the characteristics of EMGs subjected to full-wave rectification and low-pass filtering, we examined coordination of central motor commands coming to muscles of the shoulder belt and shoulders in the course of realization of cyclic bimanual movements within a horizontal plane (close to those in sculling). The performance of different motor tasks was tested: (i) movements at a comfortable stroke rate (CSR); (ii) movements at a maximum rate (MR), and (iii) movements with the feedback (FB) information, where the subject could trace the movement rate and angles of rotation of one lever of the experimental set. Two levels of external loading could be applied to the levers of the set (“oars”) in the direction counteracting efforts developed by the subject within the pulling phase. It was found that, in realization of the CSR test, the movement rate was greater at a higher loading than that in the case of a smaller mechanical resistance. The mean level of EMGs of the examined muscles under conditions of a higher loading in realization of the CSR test was greater than that in the FB test. The level of activation of the muscles in the course of the MR test demonstrated no dependence of the level of external loading. The level of correlations between EMG activities of similar muscles of the left and right upper limbs demonstrated a trend toward lowering under conditions of the presence of visual FB. It is supposed that the cognitive influence upon realization of the motor tasks is intensified under the above conditions, and the type of the performed movements becomes closer to the discrete mode.

Frog tongue acts as muscle-powered adhesive tape.

Frogs are well known to capture fast-moving prey by flicking their sticky tongues out of the mouth. This tongue projection behaviour happens extremely fast which makes frog tongues a biological high-speed adhesive system. The processes at the interface between tongue and prey, and thus the mechanism of adhesion, however, are completely unknown. Here, we captured the contact mechanics of frog tongues by filming tongue adhesion at 2000 frames per second through an illuminated glass. We found that the tongue rolls over the target during attachment. However, during the pulling phase, the tongue retractor muscle acts perpendicular to the target surface and thus prevents peeling during tongue retraction. When the tongue detaches, mucus fibrils form between the tongue and the target. Fibrils commonly occur in pressure-sensitive adhesives, and thus frog tongues might be a biological analogue to these engineered materials. The fibrils in frog tongues are related to the presence of microscopic papillae on the surface. Together with a layer of nanoscale fibres underneath the tongue epithelium, these surface papillae will make the tongue adaptable to asperities. For the first time, to the best of our knowledge, we are able to integrate anatomy and function to explain the processes during adhesion in frog tongues.

T Cells Have a Light Touch

T Cells Have a Light Touch

Anthropometry and Barbell Trajectory in the Snatch Lift for Elite Women Weightlifters

The primary objective of this study was to examine relationships between anthropometry and horizontal barbell displacement during the pulling phase of the snatch lift (SN) in elite women weightlifters. Secondary objectives included description of anthropometric and displacement characteristics, and examinations of SN performance and competitive experience. Thirty-six women weightlifters competing at the 2009 Pan American Championships participated. Participants were measured for standing height, upper limb, trunk, thigh, and shank lengths, and completed a questionnaire about competition and training experience. Horizontal displacement from lift-off to first pull maximum (Dx1) and from first pull to second pull maximum (Dx2) was determined from the heaviest successful SN using 2-dimensional video analysis. Significant correlations (p ≤ 0.05) existed between thigh and lower-limb lengths and Dx2 in 53 kg participants; lower-limb length and Dx1 in 75 kg participants; and horizontal displacement and body segment ratios involving the upper and lower extremity in multiple weight classes. Correlations between anthropometry and Dx1 also reached significance with participants grouped by barbell trajectory type. Except for the trunk and thigh, body segment lengths were significantly different (p ≤ 0.05) between weight classes. Significantly different body proportions existed in 48 kg participants compared with all other classes. Multiple thigh and trunk variables were significantly correlated with performance. Horizontal displacement values were similar to previous reports in the literature. Few significant relationships existed between displacement and performance, and none were found for competitive experience. Understanding relationships between anthropometry and barbell trajectory may be useful for optimizing SN technique.

Force generation upon T cell receptor engagement.

T cells are major players of adaptive immune response in mammals. Recognition of an antigenic peptide in association with the major histocompatibility complex at the surface of an antigen presenting cell (APC) is a specific and sensitive process whose mechanism is not fully understood. The potential contribution of mechanical forces in the T cell activation process is increasingly debated, although these forces are scarcely defined and hold only limited experimental evidence. In this work, we have implemented a biomembrane force probe (BFP) setup and a model APC to explore the nature and the characteristics of the mechanical forces potentially generated upon engagement of the T cell receptor (TCR) and/or lymphocyte function-associated antigen-1 (LFA-1). We show that upon contact with a model APC coated with antibodies towards TCR-CD3, after a short latency, the T cell developed a timed sequence of pushing and pulling forces against its target. These processes were defined by their initial constant growth velocity and loading rate (force increase per unit of time). LFA-1 engagement together with TCR-CD3 reduced the growing speed during the pushing phase without triggering the same mechanical behavior when engaged alone. Intracellular Ca2+ concentration ([Ca2+]i) was monitored simultaneously to verify the cell commitment in the activation process. [Ca2+]i increased a few tens of seconds after the beginning of the pushing phase although no strong correlation appeared between the two events. The pushing phase was driven by actin polymerization. Tuning the BFP mechanical properties, we could show that the loading rate during the pulling phase increased with the target stiffness. This indicated that a mechanosensing mechanism is implemented in the early steps of the activation process. We provide here the first quantified description of force generation sequence upon local bidimensional engagement of TCR-CD3 and discuss its potential role in a T cell mechanically-regulated activation process.

Advanced rehabilitation ergometer (ARES): A technical introduction

To optimize training relating to the coordinative skills of athletes, a special cycle ergometer ARES with decoupled cranks was developed. The system is equipped with a measurement system to measure radial and tangential forces on the pedals, additionally to the acquisition of angle velocities of the two crank wheels. Due to the decoupled cranks, every leg performs its own revolution, and has to be active even at the pulling phase, without direct support of the opposite legs downstroke. To explore the unique possibilities of ARES, 4 subjects were tested on the ergometer in a first trial. After a short acclimatization phase to get familiar with the characteristics of the bike, the following tests were performed: (1) normal biking at different numbers of revolution with the challenge to keep a 180° phase angle, and (2) special coordination tasks: a) biking with 0° phase angle, b) Stop-and-go procedures with re-synchronization of the movement, c) counter-movement with both legs moving into opposite direction, and d) a lower half circle swing. During the exercises, forces on the pedals, the crank positions and current cadence were acquired. Out of this data, torque, power, angle velocities and an efficiency parameter were determined for the left and right leg. Variations in cadence, forces and torque as a function of pedal angle are clearly visible. A dependency on number of revolutions seems to be evident, caused by the higher coordinative challenge at high velocities.

2A1-E11 吸盤振動型ポンプレス壁面移動ロボット

This paper proposes a new technique that can keep a vacuum sucker to the wall without any pump, even on a slightly leaky wall condition. By pushing and pulling cyclically, an elastic sucker can be kept attached to the wall. When the sucker is pushed, air inside is exhausted, and in every time of pulling phase, the sucker keeps its vacuum in a short time. The important character is that the impulse (product of force and time) of pulling phase can be larger than that of pushing. This means multi sucker alternate push-pull system can be realized for wall climbing. This paper also demonstrate it can make a locomotion driven by adjacent wheels with keeping suckers attached to the wall.

Safety analysis of patient transfers and handling tasks

Background:Low-back disorders are related to biomechanical demands, and nurses are among the professionals with the highest rates. Quantification of risk factors is important for safety assessment and reduction of low-back...

Electromyographic analysis of hip adductor muscles during incremental fatiguing pedaling exercise

The purpose of this study was to investigate activity of hip adductor muscles over time and during a representative crank cycle in fatiguing pedaling. Sixteen healthy men performed incremental pedaling exercise until exhaustion. During the exercise, surface electromyogram (EMG) was detected from adductor magnus (AM), adductor longus (AL), and selected thigh muscles. Temporal changes to normalized EMG in AM muscle resembled those in vastus lateralis (VL) muscle, whereas those in AL muscle showed later onset of increase from baseline compared with AM and VL muscles. During a representative crank cycle, the same level of normalized EMG was found between propulsive and pulling phases for AM muscle, whereas muscle activation of AL muscle during the pulling phase was statistically significant higher than that during the propulsive phase. We concluded that AM and AL muscles were gradually recruited over time during fatiguing pedaling exercise, but their temporal change and activation phases were not completely the same.

Single crystal growth and LPE thin film process for RE-123 superconducting materials

Fundamentals of solidification processing for high- T c superconductors (HTSC) and the progress of the crystal pulling and liquid phase epitaxy (LPE) processes were reviewed. RE-123 crystal is solidified by peritectic reaction with diffusion through the liquid. Based on this idea, a modified CZ (SRL-CP) method was developed for continuous single crystal growth. The large Nd123 single crystal, 25×25×25 mm 3 in size, was grown by optimizing the growth conditions. The high crystallinity in Y123 single crystal, which means monograin, was also realized by using Y123 seed crystals cut out of the best possible crystalline part of the single crystal grown separately. Additionally, the growth mechanism was discussed using the solidification model. In the LPE process, the highly aligned films in both c-axis and in-plane can be grown with the high superconducting characteristics, such as J c. The self-improvement mechanism for in-plane alignment due to preferential dissolution/growth was explained by the difference in the MgO/Y123 interface energies with different orientations.

Influence of Elaboration Parameters on the Properties of Tin Oxide Films Obtained by the Sol-Gel Process

The influence of elaboration parameters during the sol-gel process is studied for tin oxide films deposition. The Dip Coating Sol-Gel route can be divided into three elaboration stages: the pulling phase and the drying and densification steps. During the pulling phase, the relative humidity ratio and the withdrawal speed are found to influence the film morphology and the film thickness respectively. Then, we show how a correct control of the sample drying is able to eliminate cracks. The densification step (temperature and duration), leading to the final network, is considered in details, and resulting effects on physical properties are presented: crytallinity, optical behaviour, atomic density, stoichiometry, electrical conductivity etc... We show through these results the specificity of the tin oxide elaborated with our procedure

Biomechanical Characteristics of Preactivation and Pulling Phases of Snatch Lift

The biomechanical characteristics of 13 snatch lifts performed by 4 elite athletes were analyzed. Electromyographic data, ground reaction force index (GRFI), knee angular velocities, barbell velocities, and lifting time were obtained 0.2 s before the lift, for the first pulling phase (FP), and for the second pulling phase (SP). The preactivation, normalized electromyographic values correlated negatively with GRFI (p < .01). In the FP and SP, all of the parameters correlated positively with each other except lifting time. GRFI in the FP also correlated positively with GRFI, maximum knee angular velocities, and maximum barbell velocities of the SP (p < .01). In the SP, the ground reaction force reached its maximum first, followed by knee angular velocity and then barbell velocity. Barbell velocity reached its maximum before the knee and the hip joint were fully extended. When the correlation of parameters between the consecutive phases of snatch weight lifting was analyzed, it was demonstrated that the preactivation of trunk and leg muscles is important in the activation of the reflectory system in order to fully utilize the forces for generating lifting speed in the pulling phase.