Sung Min Son

Changes of kinematic parameters of lower extremities with gait speed: a 3D motion analysis study

[Purpose] The purpose of this study was to investigate the changes in hip, knee and ankle kinematic variables of the lower extremities at different gait speeds. [Subjects and Methods] Forty healthy subjects who had no previous history of neurological, musculo-skeletal or other medical conditions that could affect gait were recruited. The subjects were asked to walk 10u2005m down a walkway at three different gait speeds: normal gait speed, and self-selected fast, and slow speeds. The experimental order was randomly chosen across these gaits. The hip, knee and ankle kinematic data were evaluated using a VICON 3D motion analysis system and force plates. [Results] The flexion peak and external rotation peak of the knee joint significantly increased with the increase of gait speed. The plantarflexion peaks of the ankle joint significantly increased with increase of gait speed. However, none of the kinematic data of the hip joint were significantly dependent on increase of gait speed. [Conclusion] The relationship of the knee and ankle joint can be described as coupling motion which is dependent on gait speed. Our present findings suggest that coupling motion of the knee joint and plantarflexion of the ankle joint significantly increase with increase of gait speed. These results will provide important insight into gait mechanisms for the evaluation of pathological populations.

Comparison of Spatiotemporal Gait Parameters between Children with Normal Development and Children with Diplegic Cerebral Palsy

[Purpose] The purpose of this study was to determine the differences in spatiotemporal gait parameters between children with spastic diplegic CP and children with normal development (ND). [Subjects and Methods] Sixteen children (eight children with spastic diplegic CP and eight ND children) were recruited for participation as volunteers in this study. The children with CP had a Gross Motor Function Classification (GMFC) System level of between I and II. [Results] Walking velocity, cadence, stride length, and step width of children with CP with a GMFC of between I and II were a level of 60%, 77%, 73%, and 160%, respectively, of those of ND children. The percentages of right and left double-limb support were 188% and 179% higher, respectively, and the proportion of single limb support was shorter by 83% and 82%. [Conclusion] Our results provide objective evidence of distinct differences in spatiotemporal gait parameters between children with spastic diplegic CP with a GMFC level I or II and ND children and would be helpful to persons involved in the care of these children.

Changes in upper-extremity muscle activities due to head position in subjects with a forward head posture and rounded shoulders

[Purpose] This study investigated upper-extremity muscle activities in natural, ideal, and corrected head positions. [Subjects and Methods] Forty subjects with a forward head posture and rounded shoulder were recruited and randomly assigned to the natural head position group (n = 13), ideal head position group (n = 14), or corrected head position group (n = 13). Muscle activities were measured using a four-channel surface electromyography system at the sternocleidomastoideus, upper and lower trapezius, and serratus anterior muscles on the right side during an overhead reaching task. [Results] The muscle activities of the upper trapezius and serratus anterior differed significantly among head positions. Post hoc tests revealed significant differences between natural and ideal head positions, and natural and ideal head positions for both the upper trapezius and serratus anterior. [Conclusion] Recovery of normal upper trapezius and serratus anterior muscle functions plays an important role in correcting forward head posture and rounded shoulders.

Effect of constrained weight shift on the static balance and muscle activation of stroke patients

[Purpose] The purpose of this study was to evaluate the effects of constrained weight shift induced by shoe lift beneath the unaffected lower extremity, on balance functions and electromyography of the affected lower extremity of stroke patients. [Subjects and Methods] Twelve patients with unilateral stroke were recruited as volunteers for this study. The subjects were repeatedly measured in a randomized order under three conditions: no-shoe lift, and shoe lifts of 5u2005mm and 10u2005mm heights beneath the unaffected lower extremity. [Results] Standing with a 10u2005mm shoe lift for the unaffected lower extremity decreased the mean velocity of mediolateral sway compared to no-shoe lift. Regarding the velocity of anteroposterior sway, standing with 5u2005mm and 10u2005mm shoe lifts decreased the mean velocity of anteroposterior sway. The muscle activation of the affected lower extremity was not significantly different among the no-shoe lift, 5u2005mm shoe lift and 10u2005mm shoe lift conditions; however, the muscle activities of the rectus femoris, biceps femoris, tibialis anterior, and medial gastrocnemius of the affected lower extremity progressively improved with increasing height of the shoe lift. [Conclusion] A constrained weight shift to the affected side elicited by a shoe insole of 10u2005mm height on the unaffected side can improve the static standing balance of stroke patients, and it resulted in 14–24% increases in the muscle activities of the affected leg.

Exercise-induced muscle fatigue in the unaffected knee joint and its influence on postural control and lower limb kinematics in stroke patients

This study aimed to investigate the effects of exercise-induced muscle fatigue in the unaffected knee joint on postural control and kinematic changes in stroke patients. Forty participants (20 stroke patients, 20 age-matched healthy participants) were recruited. To induce fatigue, maximum voluntary isometric contractions were performed in the unaffected knee joint in a Leg Extension Rehab exercise machine using the pneumatic resistance. We measured static and dynamic balance and lower-limb kinematics during gait. Changes in postural control parameters anteroposterior sway speed and total center of pressure distance differed significantly between the stroke and control groups. In addition, changes in gait kinematic parameters knee and ankle angles of initial contact differed significantly between stroke (paretic and non-paretic) and control groups. Muscle fatigue in the unaffected knee and ankle impaired postural control and debilitates kinematic movement of ipsilateral and contralateral lower limbs, and may place the fatigued stroke patients at greater risk for falls.

Influence of Obesity on Postural Stability in Young Adults

Objectives The purpose of this study was to determine whether obesity is associated with less postural stability in young adults, and whether it is influenced by anterior pelvic tilt angle and sensory dysfunction. Methods Center of gravity (COG) velocity and total sway distance with eyes open or eyes closed on firm or foam floors were determined in 12 obese individuals and 12 individuals with normal weight. Results On firm and foam floors with eyes closed, center of gravity velocity and total sway distance were significantly greater in the obese group than in the normal-weight group. However, on firm and foam floors with eyes open, center of gravity velocity and total sway distance were not significantly different in the two groups. Conclusion The clinical implication of our findings is that obese young adults exhibit poor postural stability. Our findings also suggested that postural instability in obese individuals is associated with increased lordosis due to abdominal fat and poor integration of plantar somatosensory input.

Effect of handrail use while performing treadmill walking on the gait of stroke patients

[Purpose] The purpose of this study was to investigate how the use of handrails during treadmill walking affects the gait parameters of stroke patients. [Subjects and Methods] The participants, 30 hemiplegic stroke patients, were randomly allocated to one of three groups: the NHG group (No Handrail group, n=10), the FHG group (Front handrail group, n=10), and BHG group (Bilateral Handrail group, n=10). All the subjects’ performed treadmill walking for 30u2005min, five days a week, for a period of eight weeks. Gait parameters were evaluated using the RS-scan system. [Results] A statistically significant difference in the HM (heel-medial) area of plantar foot pressure was observed between BHG and NHG. Statistically significant difference in the HL (heel-lateral) area of plantar foot pressure was observed between BHG and NHG, and between FHG and NHG. A statistically significant difference in contact area of the rear foot was observed between BHG and NHG. [Conclusion] The results of this study show that holding handrails during treadmill training may enhance the improvement in the quality of patients’ gait (plantar foot pressure, contact area of foot).

Changes of gait parameters following constrained-weight shift training in patients with stroke

[Purpose] This study aimed to investigate the effects of training involving compelled weight shift on the paretic lower limb on gait parameters and plantar pressure distribution in patients with stroke. [Subjects and Methods] Forty-five stroke patients participated in the study and were randomly divided into: group with a 5-mm lift on the non-paretic side for constrained weight shift training (5: constrained weight shift training) (n=15); group with a 10-mm lift on the non-paretic side for constrained weight shift training (10: constrained weight shift training) (n=15); or the control group (n=15). Both, the 5 constrained weight shift training and 10 constrained weight shift training groups underwent constrained weight shift training 5 times per week for 4 weeks, whereas the control group performed ergometer exercises for lower limb muscle strengthening. [Results] The 10 constrained weight shift training group showed a significant increase in the contact surface and impulse of the hindfoot compared to the control group, and the step length and walking speed were significantly longer and faster. [Conclusion] We found that constrained weight shift training on the paretic lower limb is an effective treatment method for improving normal gait pattern in stroke patients.

Time-varying Changes in Pulmonary Function with Exposure to Prolonged Sitting

Objectives The purpose of this study was to quantify the time-varying changes in pulmonary function with exposure to prolonged sitting. Methods Twenty-one healthy volunteers were recruited. The pulmonary function of all participants was measured three times in order to assess changes over time; pulmonary function was measured before sitting, after participants had been seated for 1 hour, and after they had been seated for 2 hours. A spirometer was used to measure pulmonary function. The recorded values were forced vital capacity, forced expiratory volume in 1 second, ratio of forced expiratory volume in 1 second to forced vital capacity (forced expiratory volume in 1 second/forced vital capacity), and peak expiratory flow. Results All measured values were significantly different before sitting and after 1 hour of sitting. There were also significant differences between all measurements taken before sitting and after 2 hours of sitting. However, the measurements taken after 1 hour and 2 hours of sitting did not significantly differ. Conclusion These findings suggest that significant changes in pulmonary function occur relatively quickly when human beings are seated.

Does hemispheric lateralization influence therapeutic effects of transcranial direct current stimulation

This study investigated the effect of transcranial direct current stimulation (tDCS) polarity depending on lateralized function of task property in normal individuals performing visuomotor and simple repetitive tasks. Thirty healthy participants with no neurological disorders were recruited to participate in this study. Participants were randomly allocated into active or control condition. For the active condition, tDCS intensity was 2 mA with stimulation applied for 15 minutes to the right hemisphere (tDCS condition). For the sham control, electrodes were placed in the same position, but the stimulator was turned off after 30 seconds (sham condition). The tapping and tracking task tests were performed before and after for both conditions. Univariate analysis revealed significant difference only in the tracking task. For direct comparison of both tasks within each group, the tracking task had significantly higher Z score than the tapping task in the tDCS group (P < 0.05). Thus, our study indicates that stimulation of the right hemisphere using tDCS can effectively improve visuomotor (tracking) task over simple repetitive (tapping) task.