Abduction Adduction Research Articles

Optimal design of dexterous prosthetic hand with five-joint thumb and fingertip tactile sensors based on novel precision grasp metric

Current linkage-driven prosthetic hands still show limitations in aspects such as the thumb design and fingertip sensor. Moreover, linkage-driven prosthetic hands still lack quantitative precision grasp quality. In this study, we developed a novel thumb structure with coupled abduction–adduction and pronation–supination movement in the trapeziometacarpal joint. We also developed a fully integrated fingertip tactile sensor with all components embedded in the distal phalanx designed to facilitate in-hand precision manipulation. Furthermore, we devised a new metric to evaluate the precision grasp quality based on the force conditions during grasp. On the basis of this metric, we optimized the geometry parameters of the thumb and index finger using the Monte Carlo method. The results show that, compared with the anthropomorphic trajectory measured from a human index, the proposed method improves the grasping ability by more than 10%. Finally, we developed a prototype prosthetic hand based on the proposed design methods and demonstrated by experiment that it was able to perform human-like thumb opposition and to pass both precision and power grasp tests.

A Robust Controller for Upper Limb Rehabilitation Exoskeleton

In this paper, a portable exoskeleton for the rehabilitation of upper extremities of three degrees of freedom (DOF) is proposed. With these degrees of freedom, the exoskeleton provides the movements of flexion–extension and abduction–adduction of the arm and flexion–extension of the forearm. A robust generalized proportional integral (GPI) controller for trajectory tracking to provide smooth movements for rehabilitation with the exoskeleton is proposed. This controller only requires output measurements and is robust against different types of disturbances. Simulation results are presented in the MSC Adams® software environment in co-simulation with Matlab-Simulink® to show the controller’s performance against different types of disturbances. The results of a PID type controller are also contrasted with the results of the GPI controller.

Case report: Surgical management of a rare colossally sized neurogenic heterotrophic ossificans in the hip

A rare case of Neurogenic heterotrophic ossification in Hip region presented to our institute with gross clinical features involving global restriction of movement in the hip joint. The patient had sustained a head injury 9 months back due to road traffic accident. Initial radiographs revealed a bony mass in the left hip region from Anterior superior iliac spine to proximal shaft of femur. Later CT scan of hip revealed various facets of the condition, the expanse of the entire bony lesion was traced. A 10 x 10 x 4cm irregular bony mass was visualized in the left hip spanning the entire left hip joint. The extent of involvement of vastus muscles and gluteal muscles was still uncertain. After thorough pre operative planning the mass was excised and sent for histopathological examination. Complete range of movements were checked perioperatively after excision involving flexion, adduction abduction and rotations. The biopsy findings suggested that the specimen contained large osteoid seams with fibrocollagenous bands and striated muscle tissue suggestive of heterotrophic ossificans.

In vitro motions of the medial and lateral proximal sesamoid bones under mid-stance load conditions are consistent with racehorse fracture configurations

Proximal sesamoid bone (PSB) fractures in racehorses are likely fatigue fractures that occur due to repetitive loads and stress remodeling. The loading circumstances that may induce damage in the PSBs are not well understood. The goal of this study was to determine in three-dimensions, PSB motions relative to the opposing metacarpal condyle during simulated mid-stance loads. Seven equine cadaveric forelimbs were axially loaded in a material testing system to simulate standing and mid-stance walk, trot, and gallop load conditions (1.8–10.5 kN). Joint angles were determined by tracking the positions of bone-fixed kinematic markers. Internal-external rotation, abduction–adduction, and flexion–extension of each PSB relative to the third metacarpal condyle were compared between loads and between PSBs using an ANOVA with Tukey-Kramer post hoc tests for pairwise comparisons. The medial PSB rotated externally and the lateral PSB apex abducted during limb loading. Medial PSB external rotation was significantly greater at the gallop load condition than at the walk or trot load conditions. The medial and lateral PSB motions observed in this study are consistent with location of fatigue damage and fracture configurations frequently seen in medial and lateral PSBs from Thoroughbred racehorses. Specifically, medial PSB external rotation is consistent with the development of an abaxial subchondral medial PSB lesion that is reported in association with medial PSB transverse fracture and lateral PSB abduction is consistent with axial longitudinal fracture of the lateral PSB.

Quantitative Investigation of Hand Grasp Functionality: Thumb Grasping Behavior Adapting to Different Object Shapes, Sizes, and Relative Positions.

This paper is the first in the two-part series quantitatively modelling human grasp functionality and understanding the way human grasp objects. The aim is to investigate the thumb movement behavior influenced by object shapes, sizes, and relative positions. Ten subjects were requested to grasp six objects (3 shapes × 2 sizes) in 27 different relative positions (3 X deviation × 3 Y deviation × 3 Z deviation). Thumb postures were investigated to each specific joint. The relative position (X, Y, and Z deviation) significantly affects thumb opposition rotation (Rot) and flexion (interphalangeal (IP) and metacarpo-phalangeal (MCP)), while the object property (object shape and size) significantly affects thumb abduction/adduction (ABD) motion. Based on the F value, the Y deviation has the primary effects on thumb motion. When the Y deviation changing from proximal to distal, thumb opposition rotation (Rot) and flexion (IP and MCP joint) angles were increased and decreased, respectively. For principal component analysis (PCA) results, thumb grasp behavior can be accurately reconstructed by first two principal components (PCs) which variance explanation ratio reached 93.8% and described by the inverse and homodromous coordination movement between thumb opposition and IP flexion. This paper provides a more comprehensive understanding of thumb grasp behavior. The postural synergies can reproduce the anthropomorphic motion, reduce the robot hardware, and control dimensionality. All of these provide a more accurate and general basis for the design and control of the bionic thumb and novel wearable assistant robot, thumb function assessment, and rehabilitation.

Flexohand: A Hybrid Exoskeleton-Based Novel Hand Rehabilitation Device.

Home-based hand rehabilitation has excellent potential as it may reduce patient dropouts due to travel, transportation, and insurance constraints. Being able to perform exercises precisely, accurately, and in a repetitive manner, robot-aided portable devices have gained much traction these days in hand rehabilitation. However, existing devices fall short in allowing some key natural movements, which are crucial to achieving full potential motion in performing activities of daily living. Firstly, existing exoskeleton type devices often restrict or suffer from uncontrolled wrist and forearm movement during finger exercises due to their setup of actuation and transmission mechanism. Secondly, they restrict passive metacarpophalangeal (MCP) abduction–adduction during MCP flexion–extension motion. Lastly, though a few of them can provide isolated finger ROM, none of them can offer isolated joint motion as per therapeutic need. All these natural movements are crucial for effective robot-aided finger rehabilitation. To bridge these gaps, in this research, a novel lightweight robotic device, namely “Flexohand”, has been developed for hand rehabilitation. A novel compliant mechanism has been developed and included in Flexohand to compensate for the passive movement of MCP abduction–adduction. The isolated and composite digit joint flexion–extension has been achieved by integrating a combination of sliding locks for IP joints and a wire locking system for finger MCP joints. Besides, the intuitive design of Flexohand inherently allows wrist joint movement during hand digit exercises. Experiments of passive exercises involving isolated joint motion, composite joint motions of individual fingers, and isolated joint motion of multiple fingers have been conducted to validate the functionality of the developed device. The experimental results show that Flexohand addresses the limitations of existing robot-aided hand rehabilitation devices.

Effects of the COVID-19 confinement period on hip strength, flexibility and muscle injury rate in professional soccer players

ABSTRACT Objectives This study aimed to examine the effects of COVID-19 confinement on hamstring eccentric strength, hip adduction–abduction strength, and posterior chain flexibility in professional male soccer players. We also aimed to investigate whether muscle strength and flexibility would change when the players returned to play after COVID-19 confinement. Methods Thirty professional male soccer (Age; 24.9 ± 4.8 yrs, BMI; 22.7 ± 1.4 kg/m2) players participated in this study. Hamstring eccentric strength, hip abduction-adduction strength and posterior chain flexibility (PCF) were measured before (time 1) and after the home confinement period (time 2) and after return to play (time 3). Repeated measures of ANOVA was used for statistical analysis. Results PCF decreased from time 1 to time 2 (p = 0.005) but it increased from time 2 to time 3 (p = 0.03). Hamstring eccentric strength decreased from time 1 to time 2 for both dominant (p = 0.002) and non-dominant (p = 0.04) limbs and no difference was observed between time 2 and time 3 (p > 0.05). Hip abductor and adductor strength did not change between time 1 and time 2 (p > 0.05) but they increased from time 2 and time 3 in the dominant limb (p < 0.05). Five players (16%) had muscle injuries including hamstrings and adductors when they returned to play. Conclusion This study showed that 8-week COVID-19 confinement had an adverse effect on hamstring eccentric strength and PCF and 3 players had hamstring muscle injuries when they returned to play. Therefore, soccer players can be at risk of hamstring muscle injuries due to long-term detraining. Hip abductor and adductor strength seem not to be negatively affected by 8-week COVID-19 confinement. However, 2 players had adductor strain when they returned to play.

Kinematic differences between national and college level weightlifters during snatch technique

The aim of this study is to assess the suitability of a micro-processing unit of motion analysis (MPUMA), for monitoring, reproducing, and tracking upper limb movements. The MPUMA is based on an inertial measurement unit, a 16-bit digital signal controller and a customized algorithm. To validate the performance of the system, simultaneous recordings of the angular trajectory were performed with a video-based motion analysis system. A test of the flexo-extension of the shoulder joint during the active elevation in a complete range of 120º of the upper limb was carried out in 10 healthy volunteers. Additional tests were carried out to assess MPUMA performance during upper limb tracking. The first, a 3D motion reconstruction of three movements of the shoulder joint (flexo-extension, abduction–adduction, horizontal internal–external rotation), and the second, an upper limb tracking online during the execution of three movements of the shoulder joint followed by a continuous random movement without any restrictions by using a virtual model and a mechatronic device of the shoulder joint. Experimental results demonstrated that the MPUMA measured joint angles that are close to those from a motion-capture system with orientation RMS errors less than 3º.

Modeling and control of exoskeleton for wrist and forearm rehabilitation

This paper presents the modeling of the user’s dynamics synchronized with a wrist and forearm exoskeleton of 3 degrees of freedom (DoF). The biomechanical model includes components that are presented in post-stroke patients, such as viscosity and elasticity parameters. The dynamic model of the uncoupled exoskeleton is considered, so that the FE (flexion/extension), AA (adduction/abduction) and PS (pronation/supination) exercises are carried out one at a time, and not simultaneously. This work shows a comparison of the implementation of two control schemes, a PD control and an adaptive nonlinear PID-like controller. These schemes are applied to the motion control of the upper limb, which stands for wrist and forearm rehabilitation, with 3 DoF. To demonstrate the feasibility of our proposal, the user motion is included in the simulations, assuming human–robot interaction, and emulating a therapy session for patients with low and high spasticity. The results show that the adaptive nonlinear PID-like controller presents a lower mean square error than the PD control, for both low and high spasticity. The most important implications of the proposed study are, the possibility to track the smooth references, similar to a realistic therapy session and with an exoskeleton system; and the inference that adaptive controllers provide a good degree of robustness with respect to gain variations and uncertain dynamic effects. Our research is also important for designing high-end wrist and forearm exoskeletons for stroke patients, whose dynamics change over rehabilitation sessions; in this sense, typical controls, like PD, are not completely adequate to compensate these changes.

Newborn joint mechanics

Introduction We aimed to evaluate joint mechanics in newborn by goniometric assessment of major joints in healthy babies born at different gestational ages (GAs). Materials and methods An institution based observational study was carried out on healthy newborn babies within two days of birth. Study subjects were born at 28–41 completed weeks of gestation. The major joints of upper and lower limbs were assessed with manual goniometer for joint angles in relation to specific passive movements and range of motion (ROM) calculated where applicable. All measurements were made by a single observer with careful consideration of plane of movement and axes involved. Strength of association between joint angles and GA was quantified by Pearson’s r coefficient. Results Six major joints (shoulder, elbow, wrist, hip, knee, and ankle) were evaluated on either side in 433 babies. No significant differences were found between male and female babies and left or right side of the body. For most joints, a secular declining trend of joint angle or ROM was noted with good to strong inverse correlation with GA. The strongest associations were for flexion–extension ROM and adduction–abduction ROM at shoulder, palmar flexion at wrist and dorsiflexion at ankle joint with r values of −0.76, −0.75, −0.75, and −0.75, respectively. Conclusions The reading of a specific joint angle in the newborn infants was found to be dependent on GA. Precise calibration of gestation appropriate joint angles had laid down the foundation for functional assessment of multimodal joint mechanics. Highlights Evaluation of newborn joint angles require stringent attention toward the plane and axis of the particular joint movement being assessed. Major joint angles and range of motion in newborn infants were observed to follow a secular declining trend according to the gestational age. Precise estimation of gestation appropriate joint angle will be helpful to understand the mechanics of musculoskeletal medicine in newborn.

Consequences of Juvenile Idiopathic Arthritis on Single Leg Squat Performance in Youth.

Juvenile idiopathic arthritis (JIA) affects body structure and function outcomes that may increase the risk of acute joint injury. The purpose of this study was to examine single leg squat (SLS) biomechanics for youth with JIA and their healthy peers. The study design was a matched pair cohort study. Sixty-five youth (JIA n = 30; control n = 35) participated in this ethics-approved study. Participants performed 3 sets of 5 consecutive SLS tasks. Disease activity and functional status were assessed using the Juvenile Arthritis Disease Activity Score and Child Health Assessment Questionnaire. Indexed (most-affected leg [JIA]; dominant leg [control]) and contralateral extremity biomechanics were obtained using a 12-camera system. Outcomes included hip flexion/extension (FE), adduction/abduction (AA), and internal/external (IE) rotation range of motion (ROM). Data were analyzed using a multivariate random coefficient model in R (α⍺ = 0.05). A total of 29 matched pairs were analyzed. Youth with JIA had low disease activity and performed the SLS with a more internally rotated hip (indexed leg P = 0.023, β = -1.9°). Female participants displayed greater hip FE (indexed leg P = 0.015, β = -4.3°; contralateral leg P = 0.005, β = -4.8°) and IE ROM (indexed leg P = 0.021, β = -2.1°) than male participants. Associations were observed for body mass index and hip IE ROM (contralateral leg P = 0.001, β = -0.4°), knee flexion angle, and hip FE ROM (indexed leg P = 0.001, β = 0.4°; contralateral leg P = 0.001, β = 0.5°) and AA (indexed leg P = 0.010, β = 0.1°; contralateral leg P = 0.002, β = 0.2°). This study identified functional alterations for an SLS in youth with JIA. These findings support the use of physical therapy as part of a multidisciplinary management approach, to restore normal hip posture and movement.

On the 3D Nature of the Magpie (Aves: Pica pica) Functional Hindlimb Anatomy During the Take-Off Jump.

Take-off is a critical phase of flight, and many birds jump to take to the air. Although the actuation of the hindlimb in terrestrial birds is not limited to the sagittal plane, and considerable non-sagittal plane motion has been observed during take-off jumps, how the spatial arrangement of hindlimb muscles in flying birds facilitates such jumps has received little attention. This study aims to ascertain the 3D hip muscle function in the magpie (Pica pica), a bird known to jump to take-off. A musculoskeletal model of the magpie hindlimb was developed using μCT scans (isotropic resolution of 18.2 μm) to derive bone surfaces, while the 3D muscle path definition was further informed by the literature. Function was robustly characterized by determining the 3D moment-generating capacity of 14 hip muscles over the functional joint range of motion during a take-off leap considering variations across the attachment areas and uncertainty in dynamic muscle geometry. Ratios of peak flexion-extension (FE) to internal-external rotation (IER) and abduction-adduction (ABD) moment-generating capacity were indicators of muscle function. Analyses of 972 variations of the 3D muscle paths showed that 11 of 14 muscles can act as either flexor or extensor, while all 14 muscles demonstrated the capacity to act as internal or external rotators of the hip with the mean ratios of peak FE to IER and ABD moment-generating capacity were 0.89 and 0.31, respectively. Moment-generating capacity in IER approaching levels in the FE moment-generating capacity determined here underline that the avian hip muscle function is not limited to the sagittal plane. Together with previous findings on the 3D nature of hindlimb kinematics, our results suggest that musculoskeletal models to develop a more detailed understanding of how birds orchestrate the use of muscles during a take-off jump cannot be restricted to the sagittal plane.

A four-tendon robotic finger with tendon transmission inspired by the human extensor mechanism

This paper presents a tendon-driven robotic finger with its inspiration derived from the human extensor mechanism. The analytical model presented relates the contractions of the intrinsic muscles of the human hand to abduction–adduction and coordinated motion of proximal and distal interphalangeal joints. The design presented is simplified from the complex webs of fibers appearing in prior works, but preserves the dual role the interossei have of abducting/adducting the finger and flexing it at the metacarpal-phalangeal joint with the finger outstretched. The anatomical feature in our design is that the proximal interphalangeal joint passes through a set of lateral bands as the finger flexes. We discovered that by including a mechanical stop that causes the lateral bands to ‘fold’ at large enough flexion aids coordinated movements of the two interphalangeal joints as the finger flexes. Because it involves engineering running and sliding fits, this finger admits a concise kinematic model, which accurately predicts the tendon excursions from a known pose. In this work, however, we evaluate what happens when the model is used to search for a sequence of tendon excursions corresponding to a desired movement. We perform several such sequences of tendon excursions experimentally and present the poses that result using motion capture. We also demonstrate executing several types of grasps on an underactuated robotic hand that incorporates this finger design.

Lower extremity joint kinematics of a simulated lateral ankle sprain after drop landings in participants with chronic ankle instability

ABSTRACT This study examined lower extremity joint kinematics in individuals with chronic ankle instability (CAI) and controls during unanticipated and anticipated single-leg drop landings onto a laterally inclined platform. Physically active adults with CAI 15 (n = 15) and controls (n = 15) performed an unanticipated and anticipated 30 cm single-leg drop landing onto a 20° laterally inclined platform. Three-dimensional ankle, knee and hip-joint kinematics were recorded 200 ms pre- to 200 post-landing and analysed with a 2 (group) × 2 (landing condition) SPM ANOVA (p < 0.05). Results revealed individuals with CAI displayed significantly greater ankle internal rotation post-landing across both landing conditions. Anticipated landings elicited significantly greater pre-landing ankle inversion and external rotation, knee abduction and hip adduction. Additionally, significantly less ankle inversion, knee and hip flexion, and knee adduction and hip abduction were present during post-landing of the anticipated landing. Greater ankle internal rotation during landing may contribute to the ankle ‘giving way’ in individuals with CAI. However, preparatory and reactive proximal-joint kinematics were similar in both groups during landing. This highlights the possible role of the knee and hip joints in assisting with ankle-joint stability during anticipated inversion perturbations.

Shadow pitching deviates ball release position: kinematic analysis in high school baseball pitchers

BackgroundAlthough shadow pitching, commonly called “towel drill,” is recommended to improve the throwing motion for the rehabilitation of pitching disorders before the initiation of a throwing program aimed at returning to throwing using a ball, the motion differs from that of normal throwing. Learning improper motion during ball release (BR) may increase shoulder joint forces. Abnormal throwing biomechanics leads to injures. However, there has been no study of shadow pitching focusing on the BR position. The purpose of the present study was to evaluate the BR position and kinematic differences between shadow pitching and normal throwing. In addition, the effect of setting a target guide for BR position on throwing motion was examined in shadow pitching.MethodsThe participants included in this study were 20 healthy male students who were overhand right-handed pitchers with no pain induced by a throwing motion. Participants performed normal throwing (task 1), shadow pitching using a hand towel (task 2), and shadow pitching by setting a target of the BR position (task 3). A motion capture system was used to evaluate kinematic differences in throwing motions, respectively. Examination items comprised joint angles and the differences in BR position.ResultsBR position of task 2 shifted significantly toward the anterior, leftward, and downward directions compared with task 1. The distance of BR position between tasks 1 and 2 was 24 ± 10%. However, task 3 had decreased BR deviation compared with task 2 (the distance between 3 and 1 was 14 ± 7%). Kinematic differences were observed among groups at BR. For shoulder joint, task 2 showed the highest value in abduction and horizontal adduction among groups. In spine flexion, left rotation and thorax flexion, task 2 was significantly higher than task 1. Task 3 showed small differences compared with task 1.ConclusionsThe BR position of shadow pitching deviated significantly in the anterior, leftward, and downward directions compared with normal throwing. Furthermore, we demonstrated that the setting of BR target reduces this deviation. Thus, the target of BR position should be set accurately during shadow pitching exercises in the process of rehabilitation.

Objective Accuracy Indicators of the Single-Joint Arm Movements Simultaneous Reproduction with Closed Eyes and under Visual Control in Patients with Hemiparesis and Healthy Test Subjects (a New Method for Proprioceptive Sensitivity Objective Assessment)

Aim. We have developed a method for objective assessment of proprioceptive sensitivity (PS) based on determining the accuracy of reproduction with the eyes closed of the tested arm passive single-joint movements by active movements of the other arm during their execution. It was shown that healthy test subjects reproduce the passive movements with high accuracy, while post-stroke patients with hemiparesis reproduce a large proportion of paretic arm test movements with gross qualitative and quantitative errors. To make sure that the reproduction errors are associated with the state of PS but not with the cognitive factor or the functional state of the conditionally healthy arm, it was necessary to find out how accurately these patients are able to reproduce the test-movements under visual control. Materials and Methods. In 11 patients with a lesion in the right and in 9 patients in the left hemispheres of the brain and a control group of 23 healthy subjects, the accuracy of reproduction of the 5 elementary hand movements was studied: flexion-extension in the shoulder, elbow and wrist joints and abduction–adduction in the shoulder and wrist joints. The test person was subjected to a series of passive cyclic movements of the test hand during which he had to copy them with active movements of the other hand. The reproduction procedure for each test movement was performed first under visual control and then with the eyes closed. The angles in the test join and the same joint of the other arm were recorded. Qualitative and quantitative indicators were used to assess the degree of similarity of active and passive movements and to reveal the correspondence of copying accuracy to the previously developed conditional criterion of the norm (CCN) of PS in healthy test subjects. Results. It was shown that in healthy test subjects the accuracy of all movements copying in tests with closed eyes and 98% of movements in tests with opened eyes met the requirements of the CCN. In the group of patients in tests with eyes closed, copying only 61% of movements met this criterion. 20.4% of movements were reproduced with qualitative gross errors, 18.4% were copied qualitatively correctly but differed from CCN in quantitative indicators. In tests with visual tracking of passive movements, reproduction of 98% of movements was qualitatively correct and 83% of movements corresponded to CCN. Conclusions. The vast majority of single-articular movements of the paretic arm are copied by patients with unilateral brain damage under visual control qualitatively correctly and accurately (meeting the CCN). It means that in the course of the study of PS by the proposed method, they, as a rule, understand the motor task and can reproduce the tested movements with their conditionally healthy arm. From this it follows that the main cause of these movements impaired copying in tests with closed eyes is proprioceptive deficit.

Geometric Design and Prototyping of a (2-RRU)-URR Parallel Mechanism for Thumb Rehabilitation Therapy

In this paper, the geometrical design of a (2-RRU)-URR (where R and U stand for the revolute and universal joints, respectively) parallel mechanism was demonstrated for thumb rehabilitation therapy. This paper consists of two parts: the design procedure for the development of a thumb rehabilitation device and the user experiment with the prototype. Because the hand generally has a limited working area, the design of the hand attachment parts and the placement of the actuators requires careful consideration of the various factors. Along with the kinematic requirements of the device, the interaction between the mechanism and the fingers must be considered. The proposed mechanism has three actuators placed in the hand attachment. When the mechanism is attached to the hand, there is the possibility of collisions between the fingers of the user and the mechanism. Two design candidates were devised while considering the limited working area of the hand and the need to avoid collisions. Due to the dependency of the workspace on the placement of the actuators, a comparison of the workspace of the two candidate designs and the target workspace was carried out. The target workspace was determined through the use of thumb trajectory measurement data. A prototype was manufactured using 3D printed plastic and aluminum materials. To confirm the practical performance of the prototype, user experiments were conducted in which a comparison between the thumb measurement data and the controlled trajectory of each person was done. Motion in two directions, specifically, adduction–abduction and flexion–extension were performed. The results showed that the controlled trajectory of flexion–extension were closely matched to the thumb measurement trajectory. Finally, the experimental results are discussed.

Knee Angles After Crosstalk Correction With Principal Component Analysis in Gait and Cycling.

Principal component analysis (PCA) has been used as a post-hoc method for reducing knee crosstalk errors during gait analysis. PCA minimizes correlations between flexion-extension (FE), abduction-adduction (AA), and internal-external rotation (IE) angles. However, previous studies have not considered PCA for exercises involving knee flexion angles that are greater than those typically experienced during gait. Thus, the goal of this study was to investigate using PCA to correct for crosstalk during one exercise (i.e., cycling) that involves relatively high flexion angles. Fifteen participants were tested in gait and cycling using a motion analysis system. Uncorrected FE, AA and IE angles were compared to those calculated with PCA performed on (1) all angles (FE-AA-IE PCA correction) and (2) only FE-AA angles (FE-AA PCA correction). Significant differences existed between uncorrected and FE-AA-IE PCA corrected AA and IE angles for both exercises, between uncorrected and FE-AA PCA corrected AA angles for both exercises, and between FE-AA-IE and FE-AA PCA corrected IE angles for cycling. Correlations existed before PCA correction and were eliminated following PCA correction with the exception that FE-IE correlations remained following FE-AA PCA correction. Since the two PCA analyses differed only in their IE angle predictions for the high flexion exercise (cycling), IE angle results were compared to previous studies. Using FE-AA PCA correction may be the preferred protocol for cycling as it appeared to retain physiological IE angle correlations at high flexion angles. However, there exists a critical need for studies aimed at obtaining more accurate IE angles in such exercises.

Effect of Repetitive Passive Movement Before Motor Skill Training on Corticospinal Excitability and Motor Learning Depend on BDNF Polymorphisms.

A decrease in cortical excitability tends to be easily followed by an increase induced by external stimuli via a mechanism aimed at restoring it; this phenomenon is called “homeostatic plasticity.” In recent years, although intervention methods aimed at promoting motor learning using this phenomenon have been studied, an optimal intervention method has not been established. In the present study, we examined whether subsequent motor learning can be promoted further by a repetitive passive movement, which reduces the excitability of the primary motor cortex (M1) before motor learning tasks. We also examined the relationship between motor learning and the brain-derived neurotrophic factor. Forty healthy subjects (Val/Val genotype, 17 subjects; Met carrier genotype, 23 subjects) participated. Subjects were divided into two groups of 20 individuals each. The first group was assigned to perform the motor learning task after an intervention consisting in the passive adduction–abduction movement of the right index finger at 5 Hz for 10 min (RPM condition), while the second group was assigned to perform the task without the passive movement (control condition). The motor learning task consisted in the visual tracking of the right index finger. The results showed that the corticospinal excitability was transiently reduced after the passive movement in the RPM condition, whereas it was increased to the level detected in the control condition after the motor learning task. Furthermore, the motor learning ability was decreased immediately after the passive movement; however, the motor performance finally improved to the level observed in the control condition. In individuals carrying the Val/Val genotype, higher motor learning was also found to be related to the more remarkable changes in corticospinal excitability caused by the RPM condition. This study revealed that the implementation of a passive movement before a motor learning tasks did not affect M1 excitatory changes and motor learning efficiency; in contrast, in subjects carrying the Val/Val polymorphism, the more significant excitatory changes in the M1 induced by the passive movement and motor learning task led to the improvement of motor learning efficiency. Our results also suggest that homeostatic plasticity occurring in the M1 is involved in this improvement.

Angular variables of climbing geckos in two lateral undulation patterns

Geckos demonstrate flexible and agile locomotion on diverse terrains and surfaces. The lateral undulation pattern referring to the trunk-limbs coordination gives animals advantages in terms of motion speed, dynamical stability, and highly efficient movement. Quantitative analysis of the angular variables of the trunk and limbs was proposed to compare the kinematics of Gekko gecko on the vertical plane in the standing wave and traveling wave of lateral undulation patterns. Thirteen angular variables were measured to illustrate the kinematic characteristics of trunk flexion, girdles rotation, scapula rotation, trunk deflection, femoral/humeral protraction–retraction, abduction–adduction, and rotation around their axes, and knee/elbow flexion-extension. One-way analysis of variance (ANOVA) tested for mean differences between patterns for maximum value, minimum value, and range value of each angular variable. The geckos adapted to the changes in locomotion velocity by dynamically adjusting the joints angular variables. Twenty of the thirty-nine angular values showed a significant pattern effect that presented the variation of angular values or the timing of the peak of the angle curve in two different lateral undulation patterns. The climbing stability of a gecko is tightly associated with the coordination between the body and the limbs.