The Effects of Different Gait Speeds and Lower Arm Weight on the Activities of the Latissimus Dorsi,Gluteus Medius,and Gluteus Maximus Muscles

[Purpose] This study researched the effects of different gait speeds and lower arm weight on the activities of the latissimus dorsi, gluteus medius, and gluteus maximus muscles. [Subjects] Fourteen healthy adult men participated in this study. [Methods] All the participants carried out walking on a treadmill at speeds of 3.5 km/h and 5.5 km/h for half a minute. During treadmill gait, electromyographic activity muscle was measured of the latissimus dorsi, gluteus medius and gluteus maximus. [Result] There were significant differences in the muscle activities due to changes in gait speed and lower arm load in the latissimus dorsi and gluteus maximus, but there were no significant differences in the muscle activities of the gluteus medius. [Conclusion] According to our results, arm swing is related to increasing gait speed, and lower arm load is influences the muscle activity of the lower extremities through the posterior oblique sling system.Key words: Posterior oblique sling system, Arm weight, Arm swing     

Relationship between gait speed and trunk muscles in frail elderly individuals

[Purpose] The external and internal abdominal muscles may be related to gait speed; however, this has not yet been elucidated. In this study, we aimed to clarify the relationship between gait speed and trunk muscle thickness in elderly individuals. [Participants and Methods] The participants were 12 elderly individuals (4 males and 8 females, mean age 83.4 years old, SD ± 0.5) that attend a day service center. We measured the 5 m free gait speed, the 5 m fastest gait speed, and the thickness of five trunk muscles (the rectus abdominis [divided into three parts: upper, central, and lower], external oblique, internal oblique, transverse abdominis, and iliopsoas muscles). [Results] There were positive correlations between the free gait speed and the thickness of the lower rectus abdominis, internal oblique, and transverse abdominis muscles. There were also positive correlations between the fastest gait speed and the thickness of the lower rectus abdominis, internal oblique, and transverse abdominis muscles. [Conclusion] Incorporating muscle strength training of the lower rectus abdominis, internal oblique, and transverse abdominis muscles into existing lower limb muscle training protocols is important to effectively maintain the gait speed of elderly individuals.Key words: Gait speed, Trunk muscles, Frail elderly individuals     

Muscle Activity of the Gluteus Medius at Different Gait Speeds

[Purpose] The present study aimed to determine the changes in the muscle activities of the gluteus medius, latissimus dorsi, and gluteus maximus at different gait speeds, to collect basic data for the study of the gluteus medius. [Subjects and Methods] The subjects were 18 young and healthy male adults whose mean age, height, and weight were 26.4 years, 173.37 cm, and 72.5 kg, respectively. Electromyograpy was used to measure the maximum voluntary isometric contraction of each muscle three times and the values averaged. Then, the subjects walked on a treadmill at gait speeds of 1.5 m/s, 2.5 m/s, and 3.5 m/s and the muscle activity of each muscle was measured. [Results] The gluteus medius showed no significant difference in muscle activity among the different gait speeds. [Conclusion] For selectively strengthening the gluteus medius, to establish the external stability of the pelvis during walking, weight loading or sloped treadmills are effective interventions. However, different gait speeds exert no significant effect on the selective strengthening of the gluteus medius.Key words: Gait, Gluteus medius, Speed     

Comparison of the Activity of the Gluteus Medius According to the Angles of Inclination of a Treadmill with Vertical Load

[Purpose] The purpose of this study was to compare the muscle activity of the gluteus medius according to treadmill inclination during gait with a vertical load on a treadmill. [Methods] Sixteen healthy subjects were recruited for this study. The subjects walked on a treadmill at inclination angles of 0, 5, and 10 degrees. [Results] Muscle activity of the gluteus medius increased at 5° compared to 0° treadmill inclination, though the difference was not significant. On the other hand, gluteus medius muscle activity significantly decreased in treadmill walking at an inclination of 10° compared to 5°. [Conclusion] Selective strengthening exercises using a 5° treadmill angle could be useful for patients experiencing gluteus medius weakness.Key words: Vertical load, Gait, Gluteus medius     

Effects of walking with a “draw-in maneuver” on the knee adduction moment and hip muscle activity

[Purpose] To investigate the effect of performing a draw-in maneuver (DI) on knee adduction moment (KAM) and hip and trunk muscle activities while walking. [Participants and Methods] We included 30 healthy young adults (21.5 ± 0.6 years, 16 males and 14 females) in this study. We measured the KAM and lever arm while participants walked with either a normal gait or a DI gait. We also performed surface electromyography (EMG) of the hip and trunk muscles (i.e., internal oblique abdominal muscle [IO], external oblique abdominal muscle [EO], multifidus muscle [MF], and gluteus medius muscle [GM]). [Results] The 1st peak of the KAM was significantly lower when walking with a DI gait compared to when walking with a normal gait. The integrated EMG activity of the IO, EO, and GM during the 1st half of the stance phase, and of the IO and EO during the 2nd half of the stance phase was significantly higher during the DI than during normal gait. [Conclusion] Compared with a normal gait, a DI gait leads to a decrease in the 1st peak of the KAM as a result of the shorter lever arm, and an increase in the muscular activity of the GM, IO, and EO.Key words: Draw-in maneuver, Knee adduction moment, Hip abduction muscle activity     

Effects of Various Gait Speeds on the Latissimus Dorsi and Gluteus Maximus Muscles Associated with the Posterior Oblique Sling System

[Purpose] This study investigated the effect of different gait speeds on the muscle activities of the latissimus dorsi and gluteus maximus muscles in relation to the posterior oblique sling system. [Subjects] We recruited 14 young adult males. [Methods] We measured the left latissimus dorsi muscle activity and right gluteus maximus muscle activity of all subjects while they walked on a treadmill at speeds of 1.5 km/h, 3.5 km/h and 5.5 km/h. [Results] There was a significant increase in latissimus dorsi muscle activity with a treadmill speed of 5.5 km/h compared with 1.5 km/h and 3.5 km/h. The gluteus maximus muscle activity significantly increased in the order of 1.5 km/h < 3.5 km/h < 5.5 km/h. [Conclusion] The present results indicate that arm swing connected to increasing gait speed influences the muscle activity of the lower limbs through the posterior oblique sling system.Key words: Electromyography, Gait speed, Posterior oblique sling system     

Activation of the gluteus medius according to load during horizontal hip abduction in a one-leg stance

[Purpose] This study researched the influences of different loads on muscle activity of the posterior fibers of the gluteus medius in a one-leg standing position. [Subjects] Twenty-four healthy adult men participated in this study. [Methods] All participants performed the one-leg standing position under four conditions: the standard no-load condition, in which the non-weight-bearing leg was lifted and kept parallel to the back and then pelvic or lumbar rotation was performed without thorax rotation, and the 0 kg, 1 kg, and 3 kg load conditions, in which horizontal shoulder abduction was performed with a load of 0 kg, 1 kg, or 3 kg added to the hand. The electromyographic activity of the posterior fibers of the gluteus medius was measured using a wireless surface electromyography under all conditions. The electromyographic activity of each muscle under the four conditions during the one-leg stance was analyzed using one-way analysis of variance. [Results] The electromyographic activity of the posterior fiber of the gluteus medius was significantly increased under the 3 kg load condition compared with the no-load, 0 kg load, and 1 kg load conditions. [Conclusion] These findings indicated that muscle activation is affected by increases in load in the one-leg standing position. The load on the upper extremity influences the muscle activity of the contralateral lower extremity.Key words: Posterior fibers of the gluteus medius, Horizontal hip abduction, Load     

The Effects of Knee Joint and Hip Abduction Angles on the Activation of Cervical and Abdominal Muscles during Bridging Exercises

[Purpose] The purpose of this study was to examine the effects of the flexion angle of the knee joint and the abduction angle of the hip joint on the activation of the cervical region and abdominal muscles. [Subjects] A total of 42 subjects were enrolled 9 males and 33 females. [Methods] The bridging exercise in this study was one form of exercise with a knee joint flexion angle of 90°. Based on this, a bridging exercise was conducted at the postures of abduction of the lower extremities at 0, 5, 10, and 15°. [Result] The changes in the knee joint angle and the hip abduction angle exhibited statistically significant effects on the cervical erector spinae, adductor magnus, and gluteus medius muscles. The abduction angles did not result in statistically significant effects on the upper trapezium, erector spinae, external oblique, and rectus abdominis muscles. However, in relation to the knee joint angles, during the bridging exercise, statistically significant results were exhibited. [Conclusion] When patients with both cervical and back pain do a bridging exercise, widening the knee joint angle would reduce cervical and shoulder muscle activity through minimal levels of abduction, permitting trunk muscle strengthening with reduced cervical muscle activity. This method would be helpful for strengthening trunk muscles in a selective manner.Key words: Bridging exercise, Knee and hip joint angle, Muscle activation     

The Effect of Trunk Stabilization Exercises with a Swiss Ball on Core Muscle Activation in the Elderly

[Purpose] The purpose of this study was to investigate the effects of trunk stabilization exercise on the muscle EMG activations related to core stability. [Subjects and Methods] Fifteen elderly people in a geriatric hospital performed trunk stabilization exercises with a Swiss ball for 20 minutes five times per week for 8 weeks. Trunk muscle activations were measured using electromyography before and after the intervention. [Results] After the intervention, the muscle activations of the rectus abdominis, erector spinae, lateral low-back (quadratus lumborum and external oblique), and gluteus medius muscles increased significantly. [Conclusion] The trunk stabilization exercise with a Swiss ball significantly increased the muscle activities of the elderly.Key words: Elderly, Electromyography, Core stability     

Effect of upper extremity load on pelvic movements during wheeled upright walker use

[Purpose] This study aimed to elucidate the effects of upper extremity loading on pelvic movements during wheeled upright walker use. [Participants and Methods] Thirteen healthy male adults participated in this intervention study. Participants walked under five conditions with targeted loads on their upper extremities of 0%, 10%, 20%, 30%, and 40% of their body weights using a wheeled upright walker with armrests. Measured items included gait velocity and stride length; the angle of the maximum trunk anterior tilt; the range of motion of the trunk and pelvis in the movements of obliquity, tilt, and rotation; and the amplitude of the center of mass in the vertical and lateral directions captured and calculated using a three-dimensional motion analysis system. [Results] Increasing the load on the upper extremities did not shorten the stride or restrict pelvic movement during gait using upright walker use. The range of pelvic rotation with walker use increased versus that of the standard gait. [Conclusion] The pelvis showed quantitative movements during gait using the wheeled upright walker with armrests. These results could be helpful in the development of robotic assistive devices.     

The effects of aquatic trunk exercise on gait and muscle activity in stroke patients: a randomized controlled pilot study

[Purpose] The purpose of this study was to investigate the relationship between muscle activity and gait function following aquatic trunk exercise in hemiplegic stroke patients. [Subjects and Methods] This study’s participants included thirteen hemiplegic patients (ten males and three females). The aquatic therapy consisted of administering concentrative aquatic therapy for four weeks in a therapeutic pool. Gait parameters were measured using a gait analysis system adjusted to each subject’s comfortable walking speed. Electromyographic signals were measured for the rectus abdominis, external abdominal oblique, transversus abdominis/internal-abdominal oblique, and erector spine of each patients. [Results] The pre- and post-training performances of the transversus abdominis/internal-abdominal oblique were compared statistically. There was no statistical difference between the patients’ pre- and post-training values of maximal voluntary isometric contraction of the rectus abdominis, but the external abdominal oblique values tended to improve. Furthermore, gait factors improved significantly in terms of walking speeds, walking cycles, affected-side stance phases, affected-stride lengths, and stance-phase symmetry indices, respectively. [Conclusion] These results suggest that the trunk exercise during aquatic therapy may in part contribute to clinically relevant improvements in muscle activities and gait parameters.Key words: Aquatic trunk exercise, Gait, Muscle activity     

Effect of low back pain on the muscles controlling the sitting posture

[Purpose] The purpose of the current study was to reveal the association between posture control and muscle activity by measuring the trunk and hip joint muscle activities in the upright and slump sitting positions in both the healthy participants and patients with recurrent lower back pain. [Participants and Methods] We recruited eleven patients of recurrent lower back pain and ten healthy participants. During the maintenance of the two types of posture, upright and slump, we collected the surface electromyography data. We assessed the following muscles: rectus abdominis, external oblique, thoracic erector spinae, lumbar erector spinae, internal oblique, lumbar multifidus, iliacus, serratus anterior, rectus femoris, tensor fascia latae, and gluteus maximus. We studied the differences in spinal–pelvic curvature and muscle activity between the upright and slump positions in each group. [Results] In the healthy group, comparison of the muscle activity in upright and slump positions for both the trunk (external oblique, internal oblique, lumbar erector spinae, and lumbar multifidus), and the hip muscles (iliacus and gluteus maximus) showed a significant decrease in activity in the slump position. In the group with recurrent lower back pain, although the external oblique, lumbar erector spinae and lumbar multifidus showed reduced activity in slump position, these values were smaller when compared to those in the healthy group. [Conclusion] This study aimed to clarify the relationship between posture (upright and slump) and the activity of the trunk and hip joint muscles in the healthy participants and the patients with recurrent lower back pain. The results indicated that postural changes caused by recurrent lower back pain significantly affected the activity of the muscles involved in controlling the posture.Key words: Sitting posture, Muscle control, Low back pain     

Effects of lumbar stabilization using a pressure biofeedback unit on muscle activity and lateral pelvic tilt during hip abduction in sidelying

OBJECTIVE: To assess the effects of lumbar spine stabilization using a pressure biofeedback unit on the electromyographic activity and angle of lateral pelvic tilt during hip abduction in a sidelying position. DESIGN: Comparative, repeated-measures study. SETTING: University research laboratory. PARTICIPANTS: Eighteen able-bodied volunteers (9 men, 9 women) with no history of pathology. INTERVENTION: Subjects were instructed to perform hip abduction in a sidelying position in both the preferred hip abduction (PHA) and hip abduction with lumbar stabilization (HALS). A pressure biofeedback unit was used for lumbar stabilization. MAIN OUTCOME MEASURES: Surface electromyography was recorded from the quadratus lumborum, gluteus medius, internal oblique, external oblique, rectus abdominis, and multifidus muscles. Kinematic data for lateral pelvic tilt angle were measured using a motion analysis system. Dependent variables were examined with 2 (PHA vs HALS) x 2 (men vs women) analysis of variance. RESULTS: Significantly decreased electromyographic activity in the quadratus lumborum (PHA, 60.39% +/- 15.62% of maximum voluntary isometric contraction [MVIC]; HALS, 27.90% +/- 13.03% of MVIC) and significantly increased electromyographic activity in the gluteus medius (PHA, 25.03% +/- 10.25% of MVIC; HALS, 46.06% +/- 21.20% of MVIC) and internal oblique (PHA, 24.25% +/- 18.10% of MVIC; HALS, 44.22% +/- 20.89% of MVIC) were found when the lumbar spine was stabilized. Lateral pelvic tilt angle (PHA, 13.86 degrees +/- 4.66 degrees; HALS, 5.55 degrees +/- 4.16 degrees) was decreased significantly when the lumbar spine was stabilized. In women the electromyographic activity (percentage of MVIC) in gluteus medius, external oblique, and rectus abdominis was significantly higher than that observed in men. CONCLUSIONS: With lumbar stabilization, the gluteus medius and internal oblique activity was increased significantly, and the quadratus lumborum activity was decreased significantly, causing reduced lateral pelvic tilt in a sidelying position. These results suggest that hip abduction with lumbar stabilization is useful in excluding substitution by the quadratus lumborum.     

The in vivo dynamic response of the spine to perturbations causing rapid flexion: effects of pre-load and step input magnitude

OBJECTIVE: To evaluate the impact of muscle pre-activation levels and load magnitude on the response of the trunk to loading conditions causing rapid flexion. DESIGN: Eight male subjects were asked to maintain an upright standing posture while resisting the application of forward flexion moments produced by four different loading conditions consisting of combinations of two pre-loads (4% or 16% of the maximum extensor moment) and two added loads (12% or 24%). Pre-loading was used to develop different initial levels of trunk muscle activity prior to the application of the added loads. Of special interest were the two conditions that resulted in total final loads of 28%. BACKGROUND: Cocontraction of the antagonistic and agonistic muscles of the trunk are required to provide stability during normal physiological loading conditions. In several in vivo studies, levels of trunk muscle cocontraction have been observed prior to the application of unexpected or sudden loads. Forces from the abdominal muscles have been proposed to provide stability when extensor moments are generated. The response of trunk muscles to rapid flexor moments would provide further insight into the dynamic stability mechanisms of the spine. METHODS: Measurements were made of the trunk extensor moments, angular displacement of the trunk and unilateral surface EMG amplitudes of three abdominal and three trunk extensor muscles. Values were recorded during the isometric pre-load and for the maximum magnitude of each variable in response to the added load. RESULTS: Higher pre-loads resulted in lower flexion rotations of the spine and higher added loads caused larger rotations. With increasing magnitudes of final loads, a corresponding increase in trunk extensor moments and trunk muscle cocontraction was observed. The largest activations were observed in the lumbar erector spinae and thoracic erector spinae muscles, while smaller yet substantial EMG activity was observed in the internal oblique and external oblique. A comparison of the 28% loading conditions showed an increased response of the trunk to the [4 + 24] loading condition (with lower initial trunk stiffness) when compared to the [16 + 12] loading condition. CONCLUSIONS: Pre-activation of trunk extensor muscles can serve to reduce the flexion displacements caused by rapid loading. The abdominal oblique muscles, especially external oblique, will rapidly increase their activation levels in response to rapid loading. These changes are more pronounced when pre-activation levels are low, resulting in lower initial trunk stiffness and spine compression force. It is proposed that these factors will ultimately affect spine stability and the risk of injury. RELEVANCE: The results of this study provide insight into several mechanisms involved in the dynamic stability of the spine. Injuries can be caused by unexpected and rapid loading of the spine. A study of the mechanisms available to respond to such perturbations is important to an understanding of spine mechanics and the etiology of low back injury.     

Effect of load and carrying position on the electromyographic activity of the gluteus medius muscle during walking

Physical therapists often teach people with hip osteoarthritis ways to decrease gluteus medius muscle activity of the stance limb during gait. The rationale for decreasing this muscle activity is that hip muscle contraction needed for frontal plane hip stabilization is responsible for a large component of the hip joint compressive forces during stance. The magnitude and carrying position of external loads during walking are both variables that influence requirements of gluteus medius muscle force. Therefore, the purpose of this study was to determine through EMG, the relative amounts of gluteus medius muscle electrical activity produced during the stance phase of gait when subjects used varying combinations of load size (10 and 20% of body weight) and carrying position of the hands (contralateral or ipsilateral to a given hip, or anterior or posterior to the chest). We studied 24 healthy subjects and used their EMG activity during the stance phase of gait as an indication of the relative amount of myogenic hip compression force. Results indicated statistical differences in EMG according to carrying condition with the contralateral position (with loads of 10 and 20% of body weight) producing the highest levels of EMG. We discuss the kinesiologic reasons for results and the prevention of hip osteoarthritis in occupational settings.     

The Relationship between Physical Function and Postural Sway during Local Vibratory Stimulation of Middle-aged People in the Standing Position

[Purpose] The purpose of this study was to examine the relationship between physical function and postural sway during local vibratory stimulation of middle-aged subjects in an upright position. [Subjects] The subjects were 25 healthy community-dwelling middle-aged people. [Methods] We measured postural sway using a Wii board while vibratory stimulations of 30, 60, or 240 Hz were applied to the subjects’ lumbar multifidus or gastrocnemius muscles. Physical function was evaluated by 5-m usual gait speed and grip strength. [Results] Gait speed was strongly correlated to the anteroposterior body sway in the upright position during 30 Hz gastrocnemius muscles vibration (GMV). [Conclusion] Postural sway during 30 Hz GMV was strongly associated with gait speed and showed a posterior displacement. These findings show that the lower leg’s response to balance control under 30 Hz proprioceptive stimulation might be a good indicator of declining gait function.     

Slow Expiration Reduces External Oblique Muscle Activity during Maximum Trunk Flexion

[Purpose] The purpose of this study was to demonstrate the effects of expiration on abdominal muscle activity during maximum trunk flexion. [Subjects] Twenty-one healthy university students (10 men, 11 women) participated in this study. [Methods] Electromyography (EMG) was used to quantify the activity of the right rectus abdominis, external oblique, and internal oblique muscles. The paired t-test was used to examine the significance of differences in the abdominal muscles between maximum trunk flexion with breath holding and slow expiration. [Results] There was a significantly lower EMG activity in the external oblique muscle during maximum trunk flexion with slow expiration. [Conclusion] The results of this study indicate that slow expiration reduces external oblique muscle activity during maximum trunk flexion performed by healthy young subjects.Key words: Expiration, Electromyography, Abdominal muscles     

Intraclass correlation coefficient of trunk muscle thicknesses in different positions measured using ultrasonography

[Purpose] This study aimed to clarify the required number of measurements to calculate trunk muscle thickness at each position. [Participants and Methods] The participants were 30 elderly males aged >65 years. The right lumbar multifidus (L2), lumbar multifidus (L5), erector spinae, transversus abdominis, internal oblique, and external oblique muscle thicknesses were measured on longitudinal images obtained using ultrasonography in the lying, sitting, and standing positions. Two measurement values for each muscle thickness was used to calculate the intraclass correlation coefficient (1.1–1.5). [Results] The intraclass correlation coefficients of the abdominal muscle thickness measurements with “great reliabilities” were as follows: 1.3–1.5 for the external oblique muscle and 1.2–1.5 for the internal oblique and transversus abdominis muscles in the lying position; 1.3–1.5 for the external oblique and transversus abdominis muscles and 1.2–1.5 for the internal oblique muscle in the sitting position; the intraclass correlation coefficient in the standing position was 1.5 for the external oblique muscle 1.1–1.5 for the internal oblique muscle and 1.3–1.5 for the transversus abdominis muscle. In all the positions, the intraclass correlation coefficient of the measurements of the back-muscle thicknesses ranged from 1.1 to 1.5 for the right lumbar multifidus (L2), lumbar multifidus (L5), and erector spinae. [Conclusion] Depending on the posture, the abdominal muscles require multiple measurements, whereas the back muscles only require a single measurement.Key words: Intraclass correlation coefficient, Trunk muscle thicknesses, Ultrasonography     

Effects of flexi-bar and non-flexi-bar exercises on trunk muscles activity in different postures in healthy adults

[Purpose] The purpose of this study was to assess the effects of flexi-bar exercises and non-flexi-bar exercises on trunk muscle activity in different postures in healthy adults. [Subjects] Twenty healthy right-hand dominant adults (10 males and 10 females) were selected for this study. None of the participants had experienced any orthopedic problems in the spine or in the upper and lower extremities in the previous six months. [Methods] The subjects were instructed to adopt three exercise postures: posture 1, quadruped; posture 2, side-bridge; and posture 3, standing. Surface electromyography of selected trunk muscles was normalized to maximum voluntary isometric contraction. [Results] The external oblique, internal oblique, and erector spinae muscle activity showed significant differences between flexi-bar exercises and non-flexi-bar exercises. [Conclusion] The results of this study suggest that flexi-bar exercises are useful in the activation of trunk muscles.Key words: Flexi-bar, Vibration, Electromyography     

Influence of pelvic position and vibration frequency on muscle activation during whole body vibration in quiet standing

[Purpose] The purpose of this study was to investigate muscle activation related to postural stability depending on the pelvic position and frequency of whole body vibration (WBV) during quiet standing, and to identify the most effective training conditions that elicit the highest neuromuscular responses. [Subjects and Methods] Eighteen healthy subjects voluntarily participated in this single-group, repeated-measures study in which surface electromyography (EMG) data for the upper trapezius, rectus abdominis, external oblique abdominis, erector spinae, gluteus maximus, rectus femoris, semitendinosus, and medial gastrocnemius were collected at three frequencies (0 Hz, 10 Hz, and 20 Hz) of WBV and three pelvic positions (neutral, anterior tilt, posterior tilt) for each subject during quiet standing. [Results] The EMG activities of all the recorded muscles showed significant differences between the three frequencies of WBV and three pelvic positions during quiet standing. [Conclusion] The study findings suggest that a higher WBV frequency (20 Hz) should be used to strengthen most muscles, and that using the posterior pelvic tilt during WBV is much more effective at strengthening and training muscles related to core stability.Key words: Whole body vibration, Frequency, Pelvic tilt