Wen-Lan Wu

Gait analysis after ankle arthrodesis.

The purpose of this study was to employ a computerized motion analysis system to identify the effect of ankle arthrodesis on the three-dimensional kinematic behavior of the rear and fore foot during level walking. A three-segment rigid body model was used to describe the motion of the foot and ankle. The results demonstrated that sagittal plane motion of the hindfoot was significantly decreased in the foot of patients having had ankle arthrodesis compared to normal subjects. The kinematic data indicated a generalized stiffness of the hindfoot on the involved foot in the sagittal plane. Sagittal plane movement in the forefoot and transverse plane movements in the hindfoot and forefoot increased in patients compared to controls.

Fuzzy clustering of gait patterns of patients after ankle arthrodesis based on kinematic parameters

Kinematic parameters for 10 normal subjects and 10 patients with ankle arthrodesis are grouped using the fuzzy cluster paradigm. The features chosen for clustering are Euler angles of the sagittal plane in the hindfoot, the forefoot and combined hindfoot and forefoot joints. Gait patterns are identified using information provided by cluster validity techniques, giving three, three and two clusters for the hindfoot, forefoot and combined hindfoot and forefoot joints, respectively. The cluster centers represent distinct walking strategies adopted by normal subjects and patients after ankle arthrodesis. Utilizing angle values normalized by gait cycle, it is possible to classify any subject and to generate an individuals membership value for each of the clusters. The clinical utility of the fuzzy clustering approach is demonstrated with data for subjects with ankle arthrodesis, where changes in membership of the clusters provide an objective technique for measuring changes of gait pattern after ankle arthrodesis. This approach can be adopted to study other clinical entities where different cluster centers would be established using the algorithm provided in this study.

Three-dimensional characteristics of neck movements in subjects with mechanical neck disorder

STUDY DESIGN Controlled laboratory study. OBJECTIVES To examine characteristics of neck movement at three-dimensional planes for subjects with mechanical neck disorder (MND) and measure cervical range of motion, coupling motion, and calculation of the upper cervical rotation ratio. BACKGROUND MND is characterized by symptoms of neck pain, headache, dizziness and limited range of motion (ROM). However, the characteristics of neck movements across the three-dimensional planes in MND patients remain unknown. METHODS Forty participants were recruited, which consisted of twenty-seven subjects with MND and 13 healthy subjects. A three-dimensional electromagnetic motion capture device with custom data analysis software was used to measure the neutral position of the neck and the range of motion of upper and lower cervical spine. RESULTS The results indicate that subjects with MND had significantly decreased ROM in right rotation (p< 0.05) and extension (p< 0.05) movements compared to the healthy group. Increased coupling motion (p< 0.05) in the rotation plane during cervical flexion was also found in the MND group compared to control group. For rotations in neutral or in flexion positions, rotation to the right showed smaller range of motion compared to rotation to the left. CONCLUSION In this study, MND was associated with altered cervical movement patterns with increases in coupling motion. The findings may help to differentiate MND from whiplash-associated disorder. Increasing upper cervical spine rotation mobility may be crucial for treating deficiencies in neck rotation in patients with MND.

Effect of bilateral reaching on affected arm motor control in stroke – with and without loading on unaffected arm

Purpose. To investigate the effect of bilateral reaching, with/without inertial loading on the unaffected arm, on hemiparetic arm motor control in stroke. Methods. Twenty unilateral stroke patients were recruited. A three-dimensional optical motion capture system was used to measure the movement trajectory of the hemiparetic arm while performing three tasks: affected limb reaching forward; two-limb reaching forward; and two-limb reaching forward with inertia loading of 25% upper limb weight on the unaffected limb, respectively. Kinematical parameters were utilized to quantify the reaching performance of the affected arm. Results. No matter whether loading was applied on the unaffected arm or not, the bilateral reaching task did not significantly facilitate smoother and faster movement. Furthermore, during bilateral reaching task with/without loading on the unaffected arm, stroke patients showed slower movement, lower maximal movement velocity, feedback control dominant and discontinuous movements in the affected arm than the same task with unilateral reaching. Subjects showed the greatest active upper extremity range of motion in proximal joints during the bilateral reaching task without unaffected arm loading. The amount of trunk movement also increased during bilateral reaching either with or without loading on the unaffected arm. Patients with moderate upper extremity motor impairment performed more discontinuous movements and less active elbow range of motion during bilateral reaching tasks; however, those with mild upper extremity motor impairment performed smoother movements and demonstrated greater active elbow range of motion during bilateral reaching tasks. Conclusions. Bilateral reaching tasks with/without loading on the unaffected arm could be considered as adding challenges during motor control training. Training with bilateral arm movements may be considered as a treatment strategy, and can be incorporated in stroke rehabilitation to facilitate greater arm active movement and improve motor control performance in the affected arm.

BIOMECHANICAL ANALYSIS OF THE STANDING LONG JUMP

The purposes of the present study were to (1) investigate the effects of the arm movement and initial knee joint angle employed in standing long jump by the ground reaction force analysis and three-dimensional motion analysis; and (2) investigate how the jump performance of the female gender related to the body configuration. Thirty-four healthy adult females performed standing long jump on a force platform with full effort. Body segment and joint angles were analyzed by three-dimensional motion analysis system. Using kinetic and kinematic data, the trajectories on mass center of body, knee joint angle, magnitude of peak takeoff force, and impulse generation in preparing phase were calculated. Average standing long jump performances with free arm motion were +1.5 times above performance with restricted arm motion in both knee initial angles. The performances with knee 90° initial flexion were +1.2 times above performance with knee 45° initial flexion in free and restricted arm motions. Judging by trajectories of the center mass of body (COM), free arm motion improves jump distance by anterior displacement of the COM in starting position. The takeoff velocity with 90° knee initial angle was as much as 11% higher than in with 45° knee initial angle. However, the takeoff angles on the COM trajectory showed no significant differences between each other. It was found that starting jump from 90° bend knee relatively extended the time that the force is applied by the leg muscles. To compare the body configurations and the jumping scores, there were no significant correlations between jump scores and anthropometry data. The greater muscle mass or longer leg did not correlated well with the superior jumping performance.

EFFECT ON PLANTAR PRESSURE DISTRIBUTION WITH WEARING DIFFERENT BASE SIZE OF HIGH-HEEL SHOES DURING WALKING AND SLOW RUNNING

High heeled shoes may alter the regular loading pattern of the plantar pressure, especially increased in the forefoot area. Walking with narrow base of high heeled shoes may induce the brisk acceleration of the supported leg due to instability that increases the force on the plantar area. Particularly, this phenomenon may be amplified while slow running, but never been investigated. Materials and Methods: Plantar pressures were measured for different specific area of foot using the Pedar-X system. The effects on plantar pressure with different sized bases (1.2× 1.2 cm2 and 2.2 × 3.5 cm2) of high-heeled shoe (7.8 cm in height) were examined while walking in thirteen healthy female subjects and during slow running in nine healthy female subjects. Results: The plantar pressures of the hallux and toe while wearing narrow base high heel were significantly (p < 0.05) greater than those when walking with wearing wide base one. For both narrow and wide base heels, significantly increased (p < 0.05) plantar pressure were found in the medial forefoot while slow running at 2.0 m/s as compared with walking at 1.0 m/s and 1.5 m/s. While slow running with wearing narrow base high heel indicated significantly (p < 0.05) increased plantar pressures in the medial, central and lateral forefoot and toes regions compared with those with wearing wide base one. Conclusion: The findings suggest that if individuals have to wear high heeled shoes, it would be better to select one with a wide based heel to avoid running in at any circumstance.

EFFECTS OF SPEED AND INCLINE ON LOWER EXTREMITY KINEMATICS DURING TREADMILL JOGGING IN HEALTHY SUBJECTS

Recently, there are more people jogging with a treadmill at the gym or the home setting. The main available selected modes for treadmill jogging are speed and slope of incline. Increased speeds and incline slopes will not only increase the cardiopulmonary loading but may also alter the lower extremity (LE) movement patterns. There are few systematic investigations of the effect of the speed and incline on LE kinematics. Most studies have used 2D methods which focused on movements in sagittal plane only and this has limitations in the acquired data since lower extremity movements also include frontal and transverse planes. The current study aimed to investigate LE movement during jogging at different speeds and incline slopes using a high speed three-dimensional (3D) motion analysis system. Eighteen young healthy males were recruited. The video-based motion capture system with six CCD cameras, HIRES Expert Vision System (Motion Analysis Corporation, CA, USA), was used to collect kinematic data at a sampling frequency of 120Hz. Nineteen passive reflective markers were attached to bilateral lower extremities of the subject. The joint angle is calculated by Euler angle using the rotation sequence: 2-1-3 (y-x′-z″). Four speeds were selected: 2 m/s, 2.5 m/s, 3 m/s, 3.5 m/s with the slope at 0, and four slopes were selected: 0%, 5%,10%,15% at a speed of 3 m/s. Repeated-measures ANOVA was used to test hypotheses regarding changes in jogging condition on LE kinematic variables. The significance level was set at 0.05. As the jogging slope increased, the hip, knee and ankle demonstrated a significantly greater maximum flexion in swing phase (p<0.001), but the maximum extension angles in stance phase were relatively unchanged. Increased LE flexion during swing phase is important to ensure foot clearance with increased slope. For increased speed, the hip and ankle joints had significantly greater maximum joint extension angles during stance phase and the hip and knee joint had significantly larger maximum flexion angles in swing phase (p<0.001). Increased motion during swing phase account for a larger step length and increased motion during stance phase may facilitate the generation of power during forward propulsion as the jogging speed increased. As the slope and speed increased, LE movement patterns were changed in the transverse plane: the significantly increased (p<0.01) internal hip rotation at terminal stance, the increased toe-in of foot (p<0.001) during terminal stance phase and decreased (p<0.05) toe-out during swing phase. Increased hip motion in transverse plane could lengthen the stride distance and increase foot toe-in for providing a stable lever for push off to increase propulsion force as speed or slope is increased. By way of systematic 3D kinematic investigation of the LE in jogging, the results further elucidate the effect of changing speed and incline on LE joints movements. This information could provide guidelines for rehabilitation clinicians or coaches to select an appropriate training mode for jogging.

Acute Effects of Foam Rolling, Static Stretching, and Dynamic Stretching During Warm-ups on Muscular Flexibility and Strength in Young Adults

CONTEXT Foam rolling has been proposed to improve muscle function, performance, and joint range of motion (ROM). However, whether a foam rolling protocol can be adopted as a warm-up to improve flexibility and muscle strength is unclear. OBJECTIVES To examine and compare the acute effects of foam rolling, static stretching, and dynamic stretching used as part of a warm-up on flexibility and muscle strength of knee flexion and extension. DESIGN Crossover study. SETTING University research laboratory. PARTICIPANTS 15 male and 15 female college students (age 21.43 ± 1.48 y, weight 65.13 ± 12.29 kg, height 166.90 ± 6.99 cm). MAIN OUTCOME MEASURES Isokinetic peak torque was measured during knee extension and flexion at an angular velocity of 60°/second. Flexibility of the quadriceps was assessed by the modified Thomas test, while flexibility of the hamstrings was assessed using the sit-and-reach test. The 3 interventions were performed by all participants in random order on 3 days separated by 48-72 hours. RESULTS The flexibility test scores improved significantly more after foam rolling as compared with static and dynamic stretching. With regard to muscle strength, only knee extension peak torque (pre vs. postintervention) improved significantly after the dynamic stretching and foam rolling, but not after static stretching. Knee flexion peak torque remained unchanged. CONCLUSIONS Foam rolling is more effective than static and dynamic stretching in acutely increasing flexibility of the quadriceps and hamstrings without hampering muscle strength, and may be recommended as part of a warm-up in healthy young adults.

THE ANALYSIS OF UPPER LIMB MOVEMENT AND EMG ACTIVATION DURING THE SNATCH UNDER VARIOUS LOADING CONDITIONS

This study investigates upper limb movement and electromyography (EMG) signals during snatch under various loading conditions and discusses results from six lifting phases. Qualisys motion analysis and Noraxon EMG systems were used to record upper limb movement and muscle activity. When lifting heavy weights, the maximum shoulder flexion angle exceeded 180° in the rise phase and thus, was higher than when lifting lower weight categories. The deltoid and biceps muscles exhibited higher activity during this phase when lifting heavy weights. It can be inferred that the deltoid muscle is activated in this phase in order to maintain the shoulder in an abducted position, and to maintain hyperflexion of the biceps. Muscle activity of the deltoid and biceps in the second pull phase also increased significantly during heavy weight lifting. We infer that the effective use of these two muscles in the second pull phase would produce higher peak barbell vertical velocity, increasing the amount of weight can be lifted. Muscle activity for the latissimus dorsi during first pull showed a statistically significant increase when lifting heavy weights. This ability by the latissimus dorsi to generate higher velocities early in the concentric phase (downswing) possibly contributed to the improved final performance during heavy weight lifting.

EMG AND PLANTAR PRESSURE PATTERNS AFTER PROLONGED RUNNING

The aim of this paper is to investigate the effect of prolonged running on lower limb muscle activity, foot pressure and foot contact area. The treadmill running test was performed at a running velocity of 12 km/h for 20 minutes. Twenty-nine male students from the Army Infantry School took part in this study. For all subjects in our study, a number of variables were analyzed by the prolonged running. The EMG variables included the signal maximum amplitude of EMG linear envelope of all the muscles. Meanwhile, maximal forces and peak foot pressures in 10 anatomically defined areas of the foot, and contact area of the whole foot were analyzed. Running EMG data in each of the phases (phase 2–4) were compared to those at the beginning of the run (phase 1). Dynamic pedography data in phase 4 was compared to those of phase 1. Pedography analysis revealed a significant increase in the maximal forces and peak pressures under the medial midfoot and all forefoot regions. From phase 1 to phase 4, the maximal force increased by 32% under the medial midfoot, 29% under the first metatarsal, 34% under the second and third metatarsal, and 21% under the fourth and fifth metatarsal. The peak pressure under the medial midfoot increased by 19%, under the first metatarsal increased by 21%, under the second and third metatarsal increased by 31%, and under the fourth and fifth metatarsal increased by 21%. The averaged maximum EMG amplitudes of almost all the muscles were increased gradually as time increased. Among them, rectus femoris, gastrocnemius, soleus, and tibialis anterior muscles reach a significant amplitude at the p < 0.05 level. In conclusion, our results showed that a prolonged running under a 20 minutes limitation led to a greater increase in muscle amplitude, midfoot and forefoot loading compared with the beginning of running.