Chung-Hwi Yi

Influence of forward head posture on scapular upward rotators during isometric shoulder flexion

SUMMARY We assessed the effects of forward head posture in the sitting position on the activity of the scapular upward rotators during loaded isometric shoulder flexion in the sagittal plane. Healthy volunteers (n = 21; 11 men, 10 women) with no history of pathology participated in the study. Subjects were instructed to perform isometric shoulder flexion with the right upper extremity in both the forward head posture (FHP) and neutral head posture (NHP) while sitting. Surface electromyography (EMG) was recorded from the upper trapezius, lower trapezius, and serratus anterior muscles. Dependent variables were examined by 2 (posture)×3 (muscle) repeated measures analysis of variance. Significantly increased EMG activity in the upper trapezius and lower trapezius and significantly decreased EMG activity in the serratus anterior were found during loaded isometric shoulder flexion with FHP. Thus, FHP may contribute to work-related neck and shoulder pain during loaded shoulder flexion while sitting. These results suggest that maintaining NHP is advantageous in reducing sustained upper and lower trapezius activity and enhancing serratus anterior activity as compared with FHP during loaded shoulder flexion.

Locomotor imagery training improves gait performance in people with chronic hemiparetic stroke: a controlled clinical trial

Objective: The purpose of this study was to evaluate whether locomotor imagery training leads to clinical improvements in gait after stroke. Design: Pretest—posttest matched control design. Participants: A total of 24 people with chronic hemiparetic stroke (13 for experimental and 11 for control) were recruited in this study. Interventions: The subjects in the experimental group participated in videotape-based locomotor imagery training five days a week for four weeks. They also conducted regular physical therapy. Outcome measures: Kinematic gait parameters were collected using a three-dimensional motion analysis system. Functional gait performance was assessed using clinical measures: Activities-specific Balance Confidence Scale, Berg Balance Test, Dynamic Gait Index and modified Emory Functional Ambulation Profile. Results: After training, walking velocity increased 0.07 ± 0.06 m/s in the experimental group and 0.01 ± 0.07 m/s in the control group. In the experimental group, the affected and less affected limb stride lengths increased by 0.09 ± 0.12 m and 0.10 ± 0.07 m respectively, whereas in the control group they decreased by 0.00 ± 0.04 m and increased by 0.02 ± 0.06 m, respectively. Kinematic parameters in the lower extremity joints during walking were more improved after the training in the experimental group. Confidence in balance, postural control, dynamic balance and performance time for different environmental walking situations were also improved more in the experimental group. Conclusion: Locomotor imagery training can be considered as a useful option for restoration of ambulation for individuals with chronic hemiparetic stroke who are unable to participate in physical gait training.

Changes in neck muscle electromyography and forward head posture of children when carrying schoolbags

This study tested the effects of three alternative types of backpack on head posture and neck muscle electromyography (EMG) in children. Four loading conditions were tested: no pack; a backpack; a double pack; a modified double pack (designed with a backpack and a front pack weighing 10% and 5% of body weight, respectively). Dependent variables were neck muscle activity, forward head angle and forward head distance (the perpendicular distance from C7 to a vertical line through the tragus of the ear). Fifteen children were asked to walk at a speed of 0.8 m/s on a treadmill. The EMG activity of upper trapezius, sternocleidomastoid and midcervical paraspinals muscles and the forward head angle and forward head distance were all significantly higher when carrying a backpack than for the other conditions. When carrying a double pack, there was a backward head posture characterised by an increased negative forward head angle, decreased forward head distance, increased sternocleidomastoid EMG signal and decreased midcervical paraspinals EMG signal, compared to carrying no pack. When carrying a modified double pack, the forward head angle and forward head distance decreased when compared to carrying a backpack. These findings indicate that the modified double pack minimises postural deviation.

Comparison of Lumbopelvic Rhythm and Flexion-Relaxation Response Between 2 Different Low Back Pain Subtypes

Study Design. A cross-sectional study to compare the kinematics and muscle activities during trunk flexion and return task in people with and without low back pain (LBP). Objective. To characterize the lumbopelvic rhythms during trunk flexion and return task in a group of healthy persons and 2 different subgroups of patients with LBP, identifying the flexion-relaxation (FR) responses in each group. Summary of Background Data. The lumbopelvic rhythm is the coordinated movement of the lumbar spine and hip during trunk flexion and return and is a clinical sign of LBP. However, the reported patterns of lumbopelvic rhythm in patients with LBP are inconsistent, possibly because previous studies have examined a heterogeneous group of patients with LBP. To clarify the lumbopelvic rhythm patterns, it is necessary to study more homogeneous subgroups of patients with LBP. Methods. The study involved the following subjects: control group of healthy subjects (N = 16); lumbar flexion with rotation syndrome (LFRS) LBP subgroup (N = 17); and lumbar extension with rotation syndrome (LERS) LBP subgroup (N = 14). The kinematic parameters during the trunk flexion and return task were recorded using a 3-dimensional motion capture system, and the FR ratio of the erector spinae muscle was measured. Results. The flexion angle of the lumbar spine was larger in the LFRS subgroup than in the control group and the LERS LBP subgroup, and the hip flexion angle was larger in the LERS LBP subgroup than in the control group and LFRS subgroup. The FR response of the erector spinae muscle disappeared in the LFRS and LERS LBP subgroups. Conclusion. These results show that the lumbopelvic rhythms are different among healthy subjects and patients assigned to 2 specific LBP subgroups. These results provide information on the FR response of the erector spinae muscle. Level of Evidence: N/A

Real-time visual feedback can be used to activate scapular upward rotators in people with scapular winging: an experimental study

QUESTION Can real-time visual feedback facilitate the activity of serratus anterior in individuals with scapular winging during shoulder flexion? DESIGN Comparative, repeated-measures experimental study. PARTICIPANTS Nineteen subjects with scapular winging. INTERVENTION Participants performed isometric shoulder flexion at 60° and 90° with and without real-time visual feedback using a video camera to monitor scapular winging. OUTCOME MEASURES Activity in the upper trapezius, lower trapezius, and serratus anterior muscles was measured using surface electromyography. A video motion analysis system measured the displacement of a marker attached to the acromion in the frontal and sagittal planes. RESULTS Visual feedback significantly increased activity in the upper trapezius at 60° of shoulder flexion by 2.3% of maximum voluntary isometric contraction (95% CI 0.7 to 4.0). Visual feedback also significantly increased activity in the serratus anterior at 60° and 90° of shoulder flexion, by 3.0% (95% CI 2.3 to 3.6) and 5.9% (95% CI 3.3 to 8.5) of maximum voluntary isometric contraction respectively. These effects equated to effect sizes from 0.29 to 0.46. Visual feedback also significantly improved movement of the acromion superiorly at 60° of shoulder flexion and anteriorly at 60° and 90° of shoulder flexion. CONCLUSION Real-time visual feedback can be used to activate the upper trapezius and serratus anterior muscles and to improve movement of the scapula during shoulder flexion in people with scapular winging.

Effect of medial arch support on displacement of the myotendinous junction of the gastrocnemius during standing wall stretching.

STUDY DESIGN Controlled laboratory study. OBJECTIVES To examine the effects of standing wall stretching with and without medial arch support (WMAS versus WOMAS) on the displacement of the myotendinous junction (DMTJ) of the medial gastrocnemius, rearfoot angle, and navicular height in subjects with neutral foot alignment and pes planus. BACKGROUND Standing wall stretching is often prescribed to increase ankle dorsiflexion range of motion for sports fitness and rehabilitation. However, the effect of standing wall stretching WMAS on DMTJ is unknown. METHODS Fifteen subjects with neutral foot alignment and 15 subjects with pes planus performed standing wall stretching under WMAS and WOMAS conditions. Measurements of DMTJ and rearfoot position were performed using ultrasonography and video imaging. Navicular height was measured using a ruler. Dependent variables were examined with a 2-way mixed-design analysis of variance. The 2 factors were foot type (neutral foot versus pes planus) and stretching condition (WMAS versus WOMAS). RESULTS There were significant interactions of medial arch support by foot type for DMTJ, rearfoot angle, and navicular drop (P<.001). A post hoc paired t test showed that standing wall stretching in the WMAS condition significantly increased the DMTJ, compared to stretching in the WOMAS condition, in subjects with neutral foot (mean +/- SD, 9.6 +/- 1.6 versus 10.5 +/- 1.6 mm; difference, 0.9 mm; 99% CI: 0.4-1.4 mm) and in those with pes planus (10.0 +/- 1.8 versus 12.7 +/- 2.0 mm; difference, 2.7 mm; 99% CI: 1.9-3.5 mm) (P<.001). When comparing WOMAS and WMAS, the difference in DMTJ (1.8 mm; 99% CI: 0.9-2.7 mm) was significantly greater in subjects with pes planus than in those with neutral foot (P<.001). CONCLUSION Standing wall stretching with medial arch support maintained subtalar joint neutral position and increased the length of the gastrocnemius in subjects with pes planus. When prescribing standing wall stretching, clinicians need to emphasize the use of medial arch support to effectively stretch the gastrocnemius in subjects with pes planus.

Effects of ankle exercise combined with deep breathing on blood flow velocity in the femoral vein

Ankle exercises are commonly used to facilitate venous return in the lower extremity and to prevent deep vein thrombosis. Moreover, the respiratory cycle affects venous return. This study examined the effects of ankle exercise combined with deep breathing on the blood flow velocity in the femoral vein. Twenty healthy males (mean age 21.3 years), who had no medical history of lower extremity disease, were recruited for this study. The blood flow velocity in the femoral vein was measured while performing four exercise protocols: quiet breathing while resting (QR), deep breathing (DB), ankle exercise with quiet breathing (AQB), and ankle exercising combined with deep breathing (ADB). Using a Doppler ultrasound with an 8 MHz probe, peak blood flow velocities were collected for a 20 second period at the start of the inspiration phase in each protocol, three times. There were statistically significant differences in the peak blood flow velocity in the femoral vein with the four protocols (p lt 0.001). The mean (SD) peak blood flow velocity in the femoral vein was as follows: QR 10.1 (4.2) cm/sec, DB 15.5 (3.9) cm/sec, AQB 20.7 (6.6) cm/sec, and ADB 26.5 (9.4) cm/sec. Post hoc analyses revealed significant differences between each of the four protocols (p(adj) lt 0.01). The mean peak blood flow velocity in the femoral vein was greatest with the ADB protocol, which implies that the ADB protocol may be useful to prevent the blood stasis in patients at risk of deep vein thrombosis.

Comparison of Abdominal Muscle Activity During a Single-Legged Hold in the Hook-Lying Position on the Floor and on a Round Foam Roll

CONTEXT To improve trunk stability or trunk muscle strength, many athletic trainers and physiotherapists use various types of unstable equipment for training. The round foam roll is one of those unstable pieces of equipment and may be useful for improving trunk stability. OBJECTIVE To assess the effect of the supporting surface (floor versus round foam roll) on the activity of abdominal muscles during a single-legged hold exercise performed in the hook-lying position on the floor and on a round foam roll. DESIGN Crossover study. SETTING University research laboratory. PATIENTS OR OTHER PARTICIPANTS Nineteen healthy volunteers (11 men, 8 women) from a university population. INTERVENTION(S) The participants were instructed to perform a single-legged hold exercise while in the hook-lying position on the floor (stable surface) and on a round foam roll (unstable surface). MAIN OUTCOME MEASURE(S) Surface electromyography (EMG) signals were recorded from the bilateral rectus abdominis, internal oblique, and external oblique muscles. Dependent variables were examined with a paired t test. RESULTS The EMG activities in all abdominal muscles were greater during the single-legged hold exercise performed on the round foam roll than on the stable surface. CONCLUSIONS The single-legged hold exercise in the hooklying position on an unstable supporting surface induced greater abdominal muscle EMG amplitude than the same exercise performed on a stable supporting surface. These results suggest that performing the single-legged hold exercise while in the hook-lying position on a round foam roll is useful for activating the abdominal muscles.

Effects of a Proximity-Sensing Feedback Chair on Head, Shoulder, and Trunk Postures When Working at a Visual Display Terminal

Introduction: This study was designed to identify the effects of feedback from a proximity-sensing chair on head, shoulder, and trunk postures when working at a visual display terminal (VDT). Methods: Twenty healthy adults were asked to perform VDT work, and their forward head, forward shoulder, and trunk flexion angles were analyzed using a 3-D motion analysis system. The statistical significance of differences between without and with an auditory feedback device was tested by paired t-tests, with the significance cutoff set at α=0.05. Results: The forward head, forward shoulder, and trunk flexion angles significantly decreased during VDT work when using the proximity sensor with auditory feedback. Conclusion: We suggest that a feedback device promotes the adoption of beneficial postures, which may be effective in preventing VDT-work-related neck and upper-limb disorders.

Isometric hip abduction using a Thera-Band alters gluteus maximus muscle activity and the anterior pelvic tilt angle during bridging exercise

The purpose of this study was to investigate the effects of bridging with isometric hip abduction (IHA) using the Thera-Band on gluteus maximus (GM), hamstring (HAM), and erector spinae (ES) muscle activity; GM/HAM and GM/ES ratios; and the anterior pelvic tilt angle in healthy subjects. Twenty-one subjects participated in this study. Surface EMG was used to collect EMG data of GM, HAM, and ES muscle activities, and Image J software was used to measure anterior pelvic tilt angle. A paired t-test was used to compare GM, HAM, and ES muscle activity; the GM/HAM and GM/ES ratios; and the anterior pelvic tilt angle with and without IHA during the bridging exercise. GM muscle activity increased significantly and the anterior pelvic tilt angle decreased significantly during bridging with IHA using the Thera-Band (p < 0.05). However, there were no significant differences in the activity of the HAM and ES and the GM/HAM and GM/ES ratios between bridging with and without IHA (p > 0.05). The results of this study suggest that bridging with IHA using the Thera-Band can be implemented as an effective method to facilitate GM muscle activity and reduce the anterior pelvic tilt angle.