Jung Won Kwon

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 10 m 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.

The Intra- and Inter-rater Reliabilities of the Forward Head Posture Assessment of Normal Healthy Subjects.

[Purpose] Assessment of posture is an important goal of physical therapy interventions for preventing the progression of forward head posture (FHP). The purpose of this study was to determine the inter- and intra-rater reliabilities of the assessment of FHP. [Subjects and Methods] We recruited 45 participants (20 male subjects, 25 female subjects) from a university student population. Two physical therapists assessed FHP using images of head extension. FHP is characterized by the measurement of angles and distances between anatomical landmarks. Forward shoulder angle of 54° or less was defined as FHP. Intra- and inter-rater reliabilities were estimated using Kendall’s Taub correlation coefficients. [Results] Intra-class correlation of intra-rater measurements indicated an excellent level of reliability (0.91), and intra-class correlation of inter-rater measurements showed a good level of reliability in the assessment of FHP (0.75). [Conclusion] Assessment of FHP is an important component of evaluation and affects the design of the treatment regimen. The assessment of FHP was reliably measured by two physical therapists. It could therefore become a useful method for assessing FHP in the clinical setting. Future studies will be needed to provide more detailed quantitative data for accurate assessment of posture.

Influence of Isokinetic Strength Training of Unilateral Ankle on Ipsilateral One-legged Standing Balance of Adults.

[Purpose] The purpose of the current study was to investigate the changes in one-legged standing balance of the ipsilateral lower limb following unilateral isokinetic strength training. [Subjects and Methods] Thirty healthy adult volunteers were randomly assigned to either a training group or a control group, so that each group included 15 subjects. Subjects in the training group performed unilateral ankle isokinetic exercises of the dominant leg using the Biodex 3 PRO System for a period of four weeks. Ipsilateral one-legged standing balance was evaluated before and after the intervention with three stability indexes of balance using the Biodex System: Anterior-Posterior Stability Index (APSI), Medial-Lateral Stability Index (MLSI), and Overall Stability Index (OSI). [Results] Comparison of pre- and post-test data revealed significant improvements in strength values (dorsiflexion, plantarflexion, eversion, and inversion) and stability indexes (APSI, MLSI, OSI). [Conclusion] These results suggest that ankle strengthening exercise can be considered as a form of exercise that may assist individuals with improvement of balance.

The effect of alpha rhythm sleep on EEG activity and individuals' attention.

[Purpose] This study examined whether the alpha rhythm sleep alters the EEG activity and response time in the attention and concentration tasks. [Subjects and Methods] The participants were 30 healthy university students, who were randomly and equally divided into two groups, the experimental and control groups. They were treated using the Happy-sleep device or a sham device, respectively. All participants had a one-week training period. Before and after training sessions, a behavioral task test was performed and EEG alpha waves were measured to confirm the effectiveness of training on cognitive function. [Results] In terms of the behavioral task test, reaction time (RT) variations in the experimental group were significantly larger than in the control group for the attention item. Changes in the EEG alpha power in the experimental group were also significantly larger than those of the control group. [Conclusions] These findings suggest that sleep induced using the Happy-sleep device modestly enhances the ability to pay attention and focus during academic learning.

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.

The effect of transcranial direct current stimulation on the motor suppression in stop-signal task.

PURPOSE This study examined whether transcranial direct current stimulation (tDCS) of the primary motor cortex alters the response time in motor suppression using the stop-signal task (SST). METHODS Forty healthy subjects were enrolled in this study. The subjects were assigned randomly to either the tDCS condition or sham control condition. All subjects performed a stop-signal task in three consecutive phases: without, during or after the delivery of anodal tDCS on the primary motor cortex (the pre-tDCS motor phase, on-tDCS motor phase, and after-tDCS motor phase). RESULTS The response times of the stopping process were significantly lower in each SST motor phase during or after tDCS (p < 0.05) and shorter immediately during delivery of the tDCS, whereas there was no change after the delivery of tDCS compared to sham condition. In contrast, the response times of the going process were similar under the two conditions (p > 0.05). No subjects complained of any adverse symptoms or signs. CONCLUSION Anodal tDCS enhances voluntary going and stopping of movement in executive control. tDCS appears to be an effective modality to modulate motor suppression and its related dynamic behavioral changes in motor sequential learning.

The effects of closed and open kinetic chain exercises on lower limb muscle activity and balance in stroke survivors.

OBJECTIVE The major contributors to physical disability after stroke are the negative impairments related to loss of functional ability and muscle strength. The aim of this study was to examine the effects of close kinetic chain (CKC) exercise and open kinetic chain (OKC) exercise on muscle activation of the paretic lower limb and balance in chronic stroke subjects. METHODS Thirty-three patients with chronic stroke of over 6 months were enrolled. They were randomly allocated to three groups: CKC exercise group (n = 11), OKC exercise group (n = 11), and control group (n = 11). CKC and OKC exercise groups were trained 5 times per week for 6 weeks. The control group maintained routine activities and did not participate in any regular exercise program. All subjects were measured on muscle activation of the paretic lower limb and balance. RESULTS Muscle activation of rectus femoris (RF) and biceps femoris (BF) was significantly increased in both CKC exercise and OKC exercise groups, compared to the control group. However, muscle activation of gastrocnemius (GC) and tibialis anterior (TA) was significantly increased in only the CKC exercise group. Antero-posterior (A-P) andmedio-lateral (M-L) sway velocities (both with EO and EC) were decreased with the application of CKC exercise. CONCLUSION These findings indicate that the CKC exercise can improve lower limb muscle strength, and balance in chronic stroke, and it may carry over into an improvement in functional performance.

Effects of Progressive Resistance Training Integrated with Foot and Ankle Compression on Spatiotemporal Gait Parameters of Individuals with Stroke

[Purpose] The purpose of this study was to investigate the effect of progressive resistance training (PRT) integrated with foot and ankle compression on the gait ability of post-stroke patients. [Subjects and Methods] Participants were randomly allocated to two groups: the PRT group (n=14) and the control group (n=14). Subjects in the PRT group received training for 30 minutes, five days per week, for a period of six weeks. Gait ability was evaluated using the RsScan system. [Results] Use of PRT integrated with foot and ankle compression resulted in significant improvements in temporal parameters (gait velocity, step time, and double limb support) and spatial parameters (step length, stride length, and heel-to- heel base of support). [Conclusion] Progressive resistance training integrated with foot and ankle compression improved the gait ability of stroke patients. These results suggest the feasibility and suitability of integration of PRT with foot and ankle compression for individuals with stroke.

Changes of plantar pressure distributions following open and closed kinetic chain exercise in patients with stroke

OBJECTIVE The aim of this study is to investigate whether progressive resistive training with closed-kinetic chain (CKC) and open-kinetic chain (OKC) exercises could change plantar pressure distribution during walking in patients with stroke. METHODS Thirty-nine stroke patients were recruited and randomly divided into a CKC exercise group (n = 13), an OKC exercise group (n = 13), and a control group (n = 13). Both CKC and OKC exercise groups performed their own respective training programs 5 times per week for 6 weeks, whereas no training was done in the control group. Barefoot plantar pressure distribution was measured during walking in terms of contact area (CA), peak contact force (PCF), and contact impulse (CI) on each of three foot regions (i.e. forefoot (FF), midfoot (MF), and hindfoot (HF)). RESULTS In the CKC exercise group, there were significant changes in only the CA and PCF of HF. In the OKC exercise and control groups, no significant differences were found for all variables of plantar pressure distributions. CONCLUSION We found that resistive training with closed kinetic chain exercises could be an effective treatment method for improving normal gait patterns in stroke patients. These findings may be attributed to the fact that CKC exercise induced use of the ankle and knee muscles and provided repetitive sensory input from the affected foot.

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 5 mm and 10 mm heights beneath the unaffected lower extremity. [Results] Standing with a 10 mm 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 5 mm and 10 mm 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, 5 mm shoe lift and 10 mm 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 10 mm 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.