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     

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 Posterior Oblique Sling Activity during Hip Extension in the Prone Position on the Floor and on a Round Foam Roll

[Purpose] The aim of this study was to compare muscle activity of the posterior oblique sling during prone hip extension (PHE) on the floor and on a round foam roll. [Subjects] Twenty-two (11 male, 11 female) healthy volunteers were recruited for this study. [Methods] The participants performed PHE on the floor and on a round foam roll. Surface electromyography (EMG) was recorded from the contralateral latissimus dorsi (LD), contralateral erector spinae (ES), ipsilateral ES, ipsilateral gluteus maximus (GM), and ipsilateral biceps femoris (IBF). A paired t-test was used to compare muscle activity under the floor and round foam roll conditions. [Results] EMG activity of the contralateral LD, ipsilateral ES, and ipsilateral GM was significantly greater when PHE was performed on the round foam roll than on the floor. [Conclusion] Performing PHE on the round foam roll induced greater posterior oblique sling EMG activity than did exercise on the floor. These results suggest that the activation pattern of the posterior oblique sling during PHE is differs according to the type of surface (stable vs. unstable) on which it is performed.Key words: Foam roll, Posterior oblique sling, Prone hip extension     

Effects of orthosis on balance and gait in healthy adults

[Purpose] This study evaluated the effects of an oral orthosis that can change body alignment on the balance ability and gait of healthy adults. [Subjects and Methods] The subjects of this study were 21 University students. A gait analyzer was used to analyze the subjects’ balance ability and gait quality. Two walking speeds were used: 2 km/h, a comfortable speed, and 4 km/h, a slightly faster walking speed. [Results] The step length, and base of gait at 2 km/h differed significantly after the intervention. The total step time and step length increased significantly after the intervention. Furthermore, the total base of gait decreased significantly after the intervention. The step times of the left lower limb at 4 km/h differed significantly after the intervention. [Conclusion] The oral orthosis tested positively affects the balance ability and gait of healthy adults.Key words: Orthosis, Balance, Gait     

Trunk and pelvic coordination at various walking speeds during an anterior load carriage task in subjects with and without chronic low back pain

[Purpose] This study compared the coordination patterns of the trunk and pelvis in the transverse plane between healthy subjects and patients with chronic low back pain during an anterior load carriage task at various walking speeds. [Subjects] Ten healthy subjects and 10 patients with chronic low back pain performed an anterior carriage task with a load of 10% body weight at walking speeds of 3.5, 4.5, or 5.5 km/h. [Methods] The trunk and pelvic kinematics were measured by using a motion analysis system. During the anterior carriage task, the continuous relative phase differed significantly between groups with respect to walking speed. [Results] The continuous relative phase was more anti-phase in the chronic low back pain group than the control group. The inter-group continuous relative phase pattern was affected by walking at 5.5 km/h. [Conclusion] Compared to controls, subjects with chronic low back pain are unable to establish an in-phase between the trunk and pelvis from walking at 3.5 to 5.5 km/h during an anterior carriage task.Key words: Anterior carriage task, Chronic low back pain, Trunk and pelvis coordination     

The reliability of VO2 kinetics during a 6-minute walking test is influenced by walk speed

[Purpose] This study aimed to investigate the reliability of time constant measurements of oxygen intake at fast and comfortable speeds during a 6-min waling test. [Participants and Methods] The study included 10 healthy young males who walked at 4.5 km/h and 6.0 km/h twice for 6 min each in speed treadmill. Breath-by-breath gas exchange data were continuously measured and used to calculate the time constant of oxygen uptake. The reproducibility and variability of the variables were verified using the limit of agreement, inter-class correlation coefficient, coefficient of variation, and standard error of measurement. [Results] The limit of agreement was −8.5 to 2.3 s and −3.9 to 2.1 s for speeds 4.5 km/h and 6.0 km/h, respectively. The inter-class correlation coefficient, coefficient of variation, and standard error of measurement of the time constant for both speeds were 0.52 and 0.83, 11.2% and 6.4%, and 5.3 s and 1.8 s, respectively. [Conclusion] The results of this study suggested that the cardiopulmonary response, in terms of oxygen uptake, was more consistent during fast walking than during comfortable walking in a 6-min walking test with constant speed.     

Inefficiency of wide-based walking from the perspective of lateral center of gravity,gluteus medius muscle myoelectric activity,and cardiopulmonary parameters

[Purpose] To clarify the inefficiency of wide-based walking from kinematic and exercise physiology perspectives. [Participants and Methods] Participants consisted of 20 healthy male university students who performed treadmill walking under conditions of normal walking and wide-based walking (20-cm stride width). The lateral center of gravity movement, gluteus medius muscle myoelectric activity, oxygen uptake, minute ventilation (tidal volume, respiratory rate), heart rate, blood pressure, and rating perceived exertion just before the end of constant load exercise (4.0 km/h) were compared between the two walking conditions. [Results] All the measured parameters except for tidal volume and diastolic blood pressure were significantly higher during wide-based walking than during normal walking. However, when Δ is the difference between the two conditions, no correlation was found between Δlateral center of gravity movement, Δgluteus medius muscle myoelectric activity, Δcardiopulmonary parameters, and Δrating perceived exertion. [Conclusion] Although the precise mechanisms underlying the inefficiency of wide-based walking could not be clarified, cardiopulmonary indices such as oxygen uptake were significantly higher during wide-based walking than during normal walking. This suggests that improvement of wide-based gait is warranted from a kinematic perspective and an exercise physiology perspective.     

The Effect of a Vertical Load on Gluteus Medius Activity and Gait Characteristics during Walking

[Purpose] The present study examined the activity and the gait characteristics of the gluteus medius and the trunk stability muscles during the stance phase of gait on level ground when a vertical load corresponding to 0%, 1%, or 2% of body weight was placed on the lower extremities during the swing phase of the gait. [Methods] The subjects were 40 young males aged between 21 and 30 years. The vertical load, corresponding to 0%, 1%, 2% of weight, which was measured with an electronic scale, was placed bilaterally 3 cm above from the upper part of the lateral malleous. Electrodes were symmetrically attached to the gluteus medius, erector spinae, external oblique, and internal oblique muscles. [Results] There were significant differences in the activities of the left gluteus medius, bilateral external oblique, and right internal oblique muscles among the vertical loads of 0%, 1%, and 2% during gait. [Conclusion] Increases in vertical load were accompanied by changes in the activities of the internal and external oblique abdominal muscles to ensure the stability of the trunk under the different loads. Gait was only possible with the activity of the gluteus medius muscle and the trunk muscles resisting the different vertical loads rather than activating other muscles of the lower extremities in terms of energy efficiency.Key words: Vertical load, Gait, Gluteus medius     

The Effects of Vibration Stimuli Applied to the Shoulder Joint on the Activity of the Muscles Around the Shoulder Joint

[Purpose] The present study compared the muscle activity of the upper trapezius with those of the serratus anterior and the lower trapezius when slings, unstable surfaces, were laterally vibrated, to examine the effects of vibration during sling exercises on shoulder stabilization muscles. [Methods] The subjects performed push-up exercises on a sling and maintained isometric contraction in the final stage, while vibration was manually administered to the rope of the sling during the isometric-contraction stage. Vibration within a range of 10 cm was delivered for five seconds at a frequency of 1 Hz in time with a metronome. Vibrations were applied for five seconds at 3 Hz and 3.5 Hz, respectively. [Results] The serratus anterior showed a significant differences between isometric contraction with vibration of 3 Hz and isometric contraction with vibration of 3.5 Hz. [Conclusion] The upper trapezius and the lower trapezius showed prominent changes in muscle activity at 3.5 Hz, and the serratus anterior showed prominent changes in muscle activity at 3 Hz and 3.5 Hz. Therefore, as vibration frequency increased, making the load-bearing surface more unstable, the recruitment of the upper trapezius, the lower trapezius, and the serratus anterior increased. To perform exercises that selectively strengthen the serratus anterior, the exercises should be performed at a vibration frequency of 3 Hz.Key words: Vibration, Shoulder joint, Muscle activity     

The effects of gait velocity on the gait characteristics of hemiplegic patients

[Purpose] The present study investigated the effects of gait speed on temporal and spatial gait characteristics of hemiplegic stroke patients. [Subjects and Methods] Twenty post-stroke hemiplegic patients participated in the present study. To enhance the reliability of the analysis of the gait characteristics, the assessments were conducted three days per week at the same time every day. Each subject walked maintaining a comfortable speed for the first minute, and measurement was conducted for 30 seconds at a treadmill speed of 1 km/hour thereafter. Then, the subjects walked at a treadmill speed of 2 km/hour for 30 seconds after a 30-minute rest. The differences in the measurements were tested for significance using the paired t-test. [Results] The measures of foot rotation, step width, load response, mid stance, pre-swing, swing phase, and double stance phase showed significant difference between the gait velocities. [Conclusion] The present study provides basic data for gait velocity changes for hemiplegic patients.Key words: Gait characteristics, Gait velocity, Hemiplegia patients     

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     

Association between Muscle Synergy and Stability during Prolonged Walking

[Purpose] The purpose of this study was to examine whether changes in muscle synergy could affect gait stability or muscle activity by comparing muscle activity before and after prolonged walking. [Subjects and Methods] Twelve healthy male subjects walked on a treadmill for 10 min as a warm-up. Data were recorded from the participants during the first and last 1 min during 90 min of walking at 4.5 km/h. Electromyographic (EMG) activity was recorded for 7 leg muscles, and patterns of coordination were determined by principal component analysis (PCA). The patterns of activity within the anatomic muscle groups were additionally determined by repeating PCA. iEMG was calculated using the mean EMG for each cycle step during the 1 min walking periods. The largest Lyapunov exponent was calculated to quantify each subject’s inherent local dynamic stability. [Results] The patterns for each of the 7 muscles showed no change between the start and end periods. However, the end period showed a higher co-activation of the triceps surae, lower iEMG of the medial gastrocnemius, and a smaller largest Lyapunov exponent of the mediolateral and anteroposterior directions than those observed during the start period. [Conclusion] The increase in triceps surae co-activation may be associated with gait stability.Key words: Muscle synergy, Muscle activity, Gait stability     

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     

Comparison of ankle plantar flexor activity between double-leg heel raise and walking

[Purpose] We aimed to evaluate the difference in the muscle activity between the double-leg heel raise (DHR) and treadmill walking. [Subjects] Thirty healthy males aged 21.5 ± 1.6 years (body mass 63.6 ± 9.3 kg, height 171.0 ± 4.5 cm) participated in the study. [Methods] Electromyograms were simultaneously recorded from both heads of the gastrocnemius and the soleus of the right side during the DHR and treadmill walking. The DHR conditions were maximum plantar flexion (MPF), 3/4 MPF, 2/4 MPF, and 1/4 MPF, and the walking speeds were 20, 40, 60, 80, and 100 m/min. [Results] The muscle activity during the DHR and walking significantly increased with increments in the height of the heel raise and walking speed, respectively. Comparison of the muscle activity at MPF with that at each walking speed revealed that the muscle activity in the soleus and gastrocnemius medial head during walking exceeded that during the DHR in less than 3.3% of cases. [Conclusion] The DHR test is useful for evaluating the ankle plantar flexor activity necessary for walking.Key words: Double-leg heel raise, Walking, Plantar flexor     

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     

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     

Gluteus medius dysfunction in females with chronic ankle instability is consistent at different walking speeds

BackgroundPatients with chronic ankle instability often present with altered gait mechanics compared to ankle sprain copers. There is increasing evidence to suggest proximal neuromuscular alterations contribute to the injury etiology, however little is known about how these changes manifest during gait. The purpose of this study was to investigate ipsilateral gluteus maximus and medius functional activity ratios throughout treadmill walking at three speeds (preferred, 120% preferred, and 1.35 m per second) in chronic ankle instability patients compared to copers.Methods28 females (14 chronic ankle instability, 14 copers) walked at the three gait speeds in randomized order. Ground reaction forces and 10-s gluteal ultrasound clips were simultaneously recorded. Clips were reduced using ground reaction forces to extract 55 measurement frames. Normalized gluteal thickness measures were used to determine functional activity ratios. 2 × 3 analyses of variance were run to assess group and speed effects on gluteal outcomes throughout walking using statistical parametric mapping. Post-hoc t-tests, mean differences, and Cohen's d effect sizes were assessed for significant findings (P ≤ .05).FindingsThe chronic ankle instability group had significantly decreased gluteus medius activity throughout the entire gait cycle when compared to the coper group, independent of gait speed (P < .001, mean differences: 0.10–0.18; d: 1.00–3.17). There were no significant group or speed main effects, nor an interaction for gluteus maximus activity.InterpretationGluteal dysfunction throughout walking was identified in chronic ankle instability. The coper group remained within healthy reference muscle activity ranges, suggesting that proximal muscle activation alterations are associated chronic ankle impairments.     

Effect of Vibration Frequency on Serratus Anterior Muscle Activity during Performance of the Push-up Plus with a Redcord Sling

[Purpose] We investigated the effect of vibration at various frequencies on serratus anterior (SA) muscle activity. [Subjects] Ten male subjects were recruited. [Methods] The subjects performed the push-up plus exercise supported by straps above the surface and vertical ropes in the Redcord sling. During the push-up plus, vibrations of 0, 30, 50, or 90 Hz were applied to the Redcord sling using a mechanical vibration apparatus attached to the rope. SA muscle activity was recorded using electromyography. [Results] SA muscle activity at the 50 Hz vibration frequency was significantly higher than that of no vibration. [Conclusion] Performing the push-up plus using a Redcord sling with mechanical vibration of 50 Hz effectively increased SA muscle activity.Key words: Push-up plus, Mechanical vibration, Serratus anterior     

Synergistic effect of a rehabilitation program and treadmill exercise on pain and dysfunction in patients with chronic low back pain

[Purpose] The present study examined the influence of treadmill exercise added to a low back pain rehabilitation program on low back extensor strength, pain, and dysfunction in chronic low back pain patients. [Subjects and Methods] Twenty men aged 22–36 years with chronic low back pain were randomly divided into experimental and control groups of 10 patients each. Both groups underwent a low back pain rehabilitation program lasting 30 min each, thrice/week for 8 weeks. The experimental group was prescribed an additional 30 min of treadmill exercise without a slope at a speed of 3.0–3.5 km/h, at which patients could walk comfortably. Low back extensor strength was tested using the Medx lumbar extension machine, pain level was tested, using the visual analog scale, and dysfunction was tested, using the Oswestry Low Back Pain Disability Questionnaire. [Results] Changes in low back extensor strength by angle showed significant interaction effects between measurement time and group at 12°, 24°, and 36°. The results of the visual analog scale and Oswestry Questionnaire showed a decreasing trend after the experiment in both groups. However, there was no interaction effect of the additional treadmill exercise in the experimental group. [Conclusion] The combination of a low back pain rehabilitation program and treadmill exercise has a synergistic effect, to some extent, on the improvement of low back extensor strength and should be considered for treatment and rehabilitation of low back pain patients.Key words: Low back pain, Rehabilitation, Treadmill exercise     

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