Cluster Analysis of Subjective Shoulder Stiffness and Muscle Hardness: Associations with Central Sensitization-Related Symptoms.

Background and Objectives: Understanding the relationships between subjective shoulder stiffness, muscle hardness, and various factors is crucial. Our cross-sectional study identified subgroups of shoulder stiffness based on symptoms and muscle hardness and investigated associated factors. Materials and Methods: measures included subjective stiffness, pain, muscle hardness, and factors like physical and psychological conditions, pressure pain threshold, postural alignment, heart rate variability, and electroencephalography in 40 healthy young individuals. Results: Three clusters were identified: Cluster 1 with high stiffness, pain, and muscle hardness; Cluster 2 with low stiffness and pain but high muscle hardness; and Cluster 3 with low levels of all factors. Cluster 1 had significantly higher central sensitization-related symptoms (CSS) scores than Cluster 2. Subjective stiffness is positively correlated with psychological factors. Conclusions: our results suggest that CSS impacts subjective symptom severity among individuals with similar shoulder muscle hardness.

The Impact of Stretching Intensities on Neural and Autonomic Responses: Implications for Relaxation.

Stretching is an effective exercise for increasing body flexibility and pain relief. This study investigates the relationship between stretching intensity and relaxation effects, focusing on brainwaves and autonomic nervous system (ANS) activity. We used a crossover design with low- and high-intensity conditions to elucidate the impact of varying stretching intensities on neural activity associated with relaxation in 19 healthy young adults. Participants completed mood questionnaires. Electroencephalography (EEG) and plethysmography measurements were also obtained before, during, and after stretching sessions. The hamstring muscle was targeted for stretching, with intensity conditions based on the Point of Discomfort. Data analysis included wavelet analysis for EEG, plethysmography data, and repeated-measures ANOVA to differentiate mood, ANS activity, and brain activity related to stretching intensity. Results demonstrated no significant differences between ANS and brain activity based on stretching intensity. However, sympathetic nervous activity showed higher activity during the rest phases than in the stretch phases. Regarding brain activity, alpha and beta waves showed higher activity during the rest phases than in the stretch phases. A negative correlation between alpha waves and sympathetic nervous activities was observed in high-intensity conditions. However, a positive correlation between beta waves and parasympathetic nervous activities was found in low-intensity conditions. Our findings suggest that stretching can induce interactions between the ANS and brain activity.

Effects of axial extension on pelvic floor displacement and abdominal muscle activity during a pelvic floor muscle task.

BACKGROUND: The effects of axial extension on pelvic floor displacement and abdominal muscle activity during pelvic floor muscle (PFM) exercises are not well known. OBJECTIVE: To clarify the effect of sitting axial extension on pelvic floor displacement and abdominal muscle activity during a PFM task. METHODS: Pelvic floor displacement, abdominal muscle activity, and subjective kinesthesia of the PFM were compared between the resting and axial-extended sitting positions during a pelvic floor task in 34 healthy young men. RESULTS: No significant difference in pelvic floor displacement was observed between the resting and axial extension sitting position. Subjective kinesthesia was significantly easier to perform in axial extension than in resting sitting position during pelvic floor depression. Abdominal oblique muscle activity was higher in axial extension than in resting sitting position during pelvic floor depression. The changes in axial extension were significantly greater in the internal oblique muscles during elevation and in the internal and external oblique muscles during depression than in the lower rectus abdominis muscles. CONCLUSION: Axial extension in the sitting position does not change pelvic floor displacement during the PFM task. However, axial extension may be effective in facilitating subjective kinesthesia of PFM and in increasing oblique abdominal muscle activity.

Measuring Lumbar Motion Angle With a Small Accelerometer: A Reliability Study.

Objective: The purpose of this study was to investigate the reliability of measuring the lumbar motion angle using a small accelerometer for movement tests in the sagittal plane, and to determine the number of measurements required to obtain reliable data. Methods: In total, 102 healthy adults (56% women, 44% men; 20.1 ± 1.1 years of age) participated in this study. The intra- and interexaminer reliability of lumbar motion angle measurements during forward and backward trunk bending and prone hip extension were investigated. Lumbar motion angles were measured with small accelerometers placed at the thoracolumbar transition, lumbosacral transition, and thigh, during motion and at the final position. Intraclass correlation coefficients and Bland-Altman analysis were used for statistical analysis. Results: The intraclass correlation coefficients ranged from 0.6 to 0.8 in intraexaminer analyses and from 0.5 to 0.7 in interexaminer analyses. Intraexaminer systematic biases were found only in the maximum angle of trunk forward bending. Interexaminer biases were found in all angles of trunk forward bending. Conclusion: In the measurement of lumbar motion angle in the sagittal plane using a small accelerometer, it was necessary to repeat measurements 2 to 4 times, because a single measurement was not sufficiently reliable either within or between examiners.

Relationship between lumbar spine motor control ability and perceptual awareness during prone hip extension movement in people with low back pain.

PURPOSE: The purpose of this study was to clarify the differences in lumbar spine and hip joint motor control ability (MCA) in prone hip extension (PHE) between individuals with and without low back pain (LBP). It also aimed to determine the relationship between lumbar spine and hip joint MCA and lumbar perceptual awareness in individuals with LBP. METHODS: In total, 78 university students (20 with LBP and 58 without) were included in the study. The MCA of the lumbar spine and hip joint in PHE and perceptual awareness were evaluated. The MCA of the lumbar spine and hip joint was measured using a wearable sensor. Subsequently, a comparison of the MCA of the lumbar spine and hip joints of the participants and the relationship between MCA and lumbar perceptual awareness were examined. RESULTS: The MCA of the LBP group was higher than that of the non-LBP group in motion on the sagittal plane. In addition, perceptual awareness was negatively correlated with MCA in the sagittal plane in the lumbar spine. CONCLUSION: People with LBP had higher lumbar spine and hip joint MCA than those without LBP. Perceptual awareness was associated with lumbar spine and hip joint MCA in people with LBP. J. Med. Invest. 69 : 38-44, February, 2022.

Relationship between trunk muscle strength and trunk muscle mass and thickness using bioelectrical impedance analysis and ultrasound imaging.

BACKGROUND: Although trunk muscles are involved in many important functions, evaluating trunk muscle strength is not an easy task. If trunk muscle mass and thickness could be used as indicators of trunk muscle strength, the burden of measurement would be reduced, but the relationship between trunk muscle strength and trunk muscle mass and thickness has not been clarified. OBJECTIVE: The purpose of this study was to clarify the relationship between trunk muscle strength and trunk muscle mass by bioelectrical impedance analysis and trunk muscle thickness by ultrasound imaging in healthy adults. METHODS: One hundred and twenty-one healthy university students were included in this study. Trunk flexion/extension muscle strength and trunk muscle mass by bioelectrical impedance analysis, and trunk muscle thickness by ultrasound imaging were measured. RESULTS: Both trunk flexion strength and trunk extension strength were significantly correlated with trunk muscle mass and oblique and rectus abdominis muscle thickness. Multiple regression analysis showed that trunk extension muscle strength had an independent relationship with trunk muscle mass. CONCLUSIONS: This study demonstrated that trunk muscle mass or trunk muscle thickness can be used as an alternative means for evaluating trunk muscle strength, making the evaluation of trunk muscles less burdensome.

Relationships among lumbar hip motion angle, perceptual awareness, and low back pain in young adults.

[Purpose] We aimed to examine the relationships among low back pain, lumbar-hip motion angle, and lumbar perceptual awareness in young adults to improve the treatment of low back pain. [Participants and Methods] Data were collected from 36 university students with low back pain. The items included for evaluation were the low back pain intensity (Numeric Rating Scale), disability due to low back pain (Oswestry Low Back Pain Disability Index), lumbar spine and hip motion angles in test movements, and perceptual awareness (Fremantle Back Awareness Questionnaire). The test movements employed included trunk forward bending, trunk back bending, and prone hip extension. The motion angles of the lumbar spine and hip joints were measured using a wearable sensor. [Results] The Numeric Rating Scale was not correlated with the lumbar hip motion angle and perceptual awareness. The Oswestry Low Back Pain Disability Index was correlated with lumbar hip motion angles, at the beginning of trunk forward bending and at maximum trunk backward bending, and with perceptual awareness. [Conclusion] There are relationships among disabilities due to low back pain, lumbar hip motion angles, and perceptual awareness in each test movement; however, they vary depending on the type and angle of the test movement conducted.

Immediate effects of elongation training using an elastic band on the hip abductor muscles.

[Purpose] This study investigated the effects of elongation training on the hip abductor muscles in comparison with the effects of general hip abductor training. [Participants and Methods] This study included 39 healthy male university students. The participants were divided into elongation training and general-weighted hip abduction training groups. An elastic band was used for elongation training, and hip abduction exercises were performed with instructions to extend the foot as far as possible to stretch the band. Measurements were taken before and after training, and the surface electromyographic data of the gluteus medius and the tensor fasciae latae were measured during isometric contraction of the hip abductor muscles. The surface electromyogram data were used to calculate integral values and median power frequencies to compare the effects of training. [Results] In comparison with general hip abductor training, elongation training yielded a larger change in the ratio of muscle integral values (gluteus medius/tensor fasciae latae). [Conclusion] Elongation training of the hip abductor muscles was more useful than general training in increasing the activity of the gluteus medius while suppressing the activity of the tensor fasciae latae.

Intra-rater reliability of measurement of abdominal perimuscular connective tissue thickness on ultrasound images.

[Purpose] The thickness of the perimuscular connective tissue (PMCT) reflects muscular atrophy and decreased flexibility that may cause low back pain. However, few studies have used ultrasound imaging to measure PMCT thickness. We aimed to examine and confirm the reliability of ultrasound in measuring the thickness of the PMCT of the abdominal wall muscle. [Participants and Methods] The participants were 38 healthy adult males without chronic back pain. The images were acquired in B mode with the participants in the supine position and the PMCT thickness of the abdominal wall muscle was measured on the images. The intraclass correlation coefficient (ICC) was used to confirm reliability. [Results] The ICC for both within-day and between-day PMCT measurements by ultrasound were 0.7-0.9. The 95% confidence interval ranged from 0.5-0.9. The standard error of measurement (SEM) was 0.02-0.1 mm in the abdominal wall muscle and 0.5 mm in the interrecti distance (IRD). The 95% confidence interval (95% CI) of the minimum detectable change (MDC95) was 0.1-0.3 mm in the abdominal wall muscle and 1.3-1.4 mm in the IRD. [Conclusion] We conducted a study to confirm the reliability of ultrasound-based measurement of PMCT thickness of the abdominal wall muscle, and the ICC results established reliability. However, since the values measured were small (0.02-1.4 mm) and there is a limit to visual observation, it was necessary to measure using computer software.

Relationship Between Lumbar Motor Control Ability and Spinal Curvature in Elderly Individuals.

This study aimed to clarify the relationship between spine curvature and the movement pattern/motor control ability of the lumbar and hip joints during prone hip extension in elderly individuals. The participants were 14 elderly people who attended a community health class. We measured the motion angle, motion ratio (movement pattern), and motor control ability of the lumbar and hip joints during prone hip extension. In addition, the lumbar lordosis angle and thoracic kyphosis angle were measured in the standing position. There was no correlation between the spinal curvature in the standing position and the lumbar/hip joint movement pattern and motor control ability during prone hip extension. When evaluating the lumbar spine, it is necessary to perform a comprehensive evaluation by interpreting static evaluations such as spinal alignment or dynamic evaluations such as movement patterns and motor control abilities.

Change in muscle thickness during exercise to stabilize the hip joint against a load in the ventral direction of the femoral head.

[Purpose] This study aimed to measure the thickness of the muscles located on the ventral side of the hip joint and to identify the muscles involved in exercise against the load that results in femoral head translation in the ventral direction, which can be used as an index of exercise performance for the prevention and improvement of hip joint disease caused by femoral head translation. [Participants and Methods] The participants were 10 healthy young males. During the measurement task, we asked them to hold a 10 kgf load in the ventral direction to the femoral head in the supine position. We measured the thickness of the gluteus minimus, gluteus medius, tensor fascia latae, and iliopsoas both at rest and during exercise using ultrasonography. [Results] We compared muscle thicknesses at rest and during exercise and found that only the gluteus minimus had significantly lower values during exercise. We also compared the rate of change in muscle thickness and found that the gluteus minimus exhibited significantly higher values than those of the gluteus medius and tensor fasciae latae. [Conclusion] Our study indicates that the gluteus minimus is more involved than the gluteus medius, tensor fasciae latae, and iliopsoas in the exercise for the ventral displacement of the femoral head.

Examination of the intrarater reliability of ultrasound measurements of the thickness of the lumbar and lateral abdominal muscles in the prone position.

[Purpose] This study aimed to examine the intrarater reliability when measuring the thickness of the lumbar and lateral abdominal muscles using ultrasound with the participants in the prone position. [Participants and Methods] The participants were 10 healthy adult males without chronic low back pain. The muscle thicknesses of the lumbar multifidus, erector spinae, obliquus externus abdominis, obliquus internus abdominis, and transversus abdominal muscles were measured using ultrasound with the participants in the prone position. [Results] The intraclass correlation coefficients of the within-day and between-day intrarater reliability measurements were 31.1-34.1 mm (lumbar multifidus), 32.0-33.5 mm (erector spinae), 7.4-8.0 mm (obliquus externus abdominis), 9.4-10.4 mm (obliquus internus abdominis), and 2.9-3.4 mm (transversus abdominal). The standard error of measurement and 95% confidence interval of minimal detectable change of the within- and between-day measurements were 0.1-1.2 mm and 0.3-3.4 mm, respectively, for each muscle. [Conclusion] The reliability of measuring the lumbar and lateral abdominal muscles in the prone position using ultrasound was confirmed. It was suggested that measurements during muscle activity and extremity movement are possible when participants are in the prone position.

Optimal Conditions for Obtaining Valid Step Count Measurements in Hospitalized Patients with Abnormal Gait.

OBJECTIVE: This study investigated the optimum conditions for obtaining valid step-count measurements for patients with abnormal gait. METHODS: Subjects comprised 61 hospitalized patients with abnormal gait. Four different devices were tested: Active Style Pro (AS), Walking Style (WS), Lifecorder PLUS, and Steps. The same device type was attached to the waist on both the affected and the unaffected side. Patients then walked 25 m at a comfortable speed. This test was repeated four times, once for each device. The measurement error (ME) and walking parameters (gait velocity, step length, and cadence) were calculated from the test data. ME scores smaller than 3% and 10% were classified as valid: scores above these standards were classified as invalid. Walking parameter values that identified the invalid group with a specificity of 0.95 were set as the cut-off velocity (COV), the cut-off step length (COS), and the cut-off cadence. Sensitivity values >0.40 and positive predictive values >80% were then set as necessary conditions. RESULTS: COV values were 0.90 m/s (AS on the unaffected side at 3% ME and AS on the affected side or the unaffected side at 10% ME), 0.92 m/s (WS on the unaffected side at 10% ME), and 0.98 m/s (WS on the affected side at 3% ME). COS values were 0.50 m (AS on the affected side at 10% ME) and 0.52 m (AS on the unaffected side at 3% ME). CONCLUSION: The most accurate measurements were obtained using AS attached to the unaffected side with a gait velocity of >0.90 m/s.

Examinations of factors influencing toe grip strength.

[Purpose] This study examined the relationship between toe grip strength and its associated factors by focusing on factors that were suggested to have a relationship with toe grip strength in previous studies, aiming to clarify the factors influencing the toe grip strength of healthy women. [Subjects and Methods] Twelve healthy young women were selected for this study. Their toe grip strength, angular changes in their ankle joint during toe grip, maximum voluntary contraction activities of the rectus femoris, biceps femoris, and tibialis anterior muscles, and the medial head of the gastrocnemius muscles were measured using electromyography. Their toe curl ability, foot-arch height ratio, and weight were also measured. [Results] Multiple regression analysis demonstrated that the predictors of toe grip strength in the resulting model were foot-arch height ratio and the percentage of integrated electromyography (%IEMG) of the tibialis anterior muscle, as the dependent variables. This reveals that women whose tibialis anterior muscle %IEMG values and foot-arch height ratio are high have greater %IEMG values have greater toe grip strength. [Conclusion] These findings suggest a significant relationship between foot-arch height ratio and toe grip strength, with a reciprocal interaction. These findings further indicate that the risk of falls by the elderly could be decreased if toe grip strength were enhanced, by increasing the height of a low foot-arch with the help of an inserted insole.

Comparison of toe grip strength and muscle activities during maximal toe grip strength exertion according to the presence/absence of an ankle immobilization belt.

[Purpose] The aim of this study was to compare toe grip strength and muscle activity during toe grip strength exertion according to the presence/absence of an ankle immobilization belt and to examine the relationship between the differences in muscle activity and toe grip strength. [Subjects] The Subjects were 13 healthy young women. [Methods] We measured toe grip strength and muscle activity during toe grip strength exertion in the presence and absence of an ankle immobilization belt using electromyography. Activity in the following leg muscles was recorded: rectus femoris, biceps femoris, medial head of the gastrocnemius, and tibialis anterior. We then calculated the percent integrated electromyography during toe gripping. [Results] Toe grip strength and percent integrated electromyography of the medial head of the gastrocnemius muscle were significantly higher with ankle belt immobilization compared with without ankle belt immobilization. In addition, in the presence of ankle belt immobilization, the percent integrated electromyography of the tibialis anterior muscle and medial head of the gastrocnemius muscle demonstrated a positive correlation with toe grip strength (r = 0.75 and r = 0.65, respectively). [Conclusion] These findings suggest that greater toe grip strength could be exerted in the presence of ankle belt immobilization. The measured values reflect the percent integrated electromyography of the crural muscles. Therefore, it was shown that toe grip strength should be measured in the presence of an immobilization belt.

Kinematic analysis during toe-gripping strength exertion: angular changes in the ankle joint and leg muscle activities.

[Purposes] To investigate angular changes in the ankle joint and leg muscle activities during toe-gripping, and to examine the relationship between these changes and toe-gripping strength. [Subjects] Eleven healthy young women were selected. [Methods] We measured the toe-gripping strength, angular changes in the ankle joint, and leg muscle activities of all patients during toe-gripping. [Results] The mean change in the ankle angle in dorsiflexion from a neutral position was 3°, and a positive correlation was observed between this angle and toe-gripping strength (r = 0.61). Thus, toe-gripping strength increased with the angle of dorsiflexion. Regarding the leg muscle activities, activities of the tibialis anterior muscle and medial head of the gastrocnemius muscle demonstrated positive correlations with toe-gripping strength (r = 0.75 and r = 0.72, respectively). [Conclusion] These findings suggest that the ankle dorsiflexes in order to exert great toe-gripping strength, and the crural muscles contract simultaneously because of ankle fixation.

Lumbar lordosis angle (LLA) and leg strength predict walking ability in elderly males.

There is an association between gait performance and spinal alignment in elderly females but it is unclear if this association is gender-dependent and postural changes would also predict gait performance in healthy elderly males. We measured thoracic kyphosis angle (TKA), LLA as indices of spinal alignment and maximal walking speed (WS), timed up and go test (TUG), 10-m obstacle walking time, and 6-min walk distance as indices of gait performance in healthy old males (n=124, age 73.0 ± 7.2 years). Knee extensor strength and one-leg standing time with eyes open were measures of physical function. The LLA but not TKA correlated with performance in each of the 4 gait test. Multiple-regression analyses showed that only the combination of knee extensor strength and LLA accounted for significant variation in gait performance. While previous studies showed that spinal alignment is associated with gait performance in elderly women, in healthy elderly males both functional (leg strength) and structural (spinal alignment) factors contribute to gait performance.

Factors that delay COPD detection in the general elderly population.

BACKGROUND: In patients with COPD, early detection and rapid treatment are essential to prevent its progression and exacerbations. OBJECTIVE: To identify factors that delay COPD detection. METHODS: We conducted a cross-sectional study of elderly COPD patients and healthy subjects in rural Japan. We measured respiratory and physical function (hand grip force, maximum inspiratory pressure, maximum expiratory pressure, total trace length, and toe grasp force), walking ability, and quality of life (QOL, measured with a visual analog scale). We conducted spirometry in 408 subjects, whom we divided into 2 groups: those whose ratio of FEV(1) to forced vital capacity (FVC) was < 70% (the airway-obstruction group, n = 60), and those whose FEV(1)/FVC was ≥ 70% (the healthy-subjects group, n = 348). To avoid confounding, we then matched 60 subjects from the healthy-subjects group to the 60 in the airway-obstruction group for age, sex, height, and smoking history, so both groups had 60 subjects. RESULTS: Physical function was significantly inferior in the airway-obstruction group. Variables reflecting instantaneous walking ability (maximum walking speed and walking time in the 10-m hurdle walk) were significantly inferior in the airway-obstruction group, but there were no significant differences in 6-min-walk test, which reflects walking endurance, or in QOL. CONCLUSIONS: Walking endurance, QOL, and proximal muscle strength in the extremities of patients with COPD were well preserved, which prevented detection of COPD and hampered the subjects' motive for seeking medical care. In consequence, lack of awareness impeded the early detection of COPD. In primary healthcare for the general elderly population, spirometry is much easier to conduct than physical function tests, so we recommend that spirometry screening programs for early-stage COPD detection and staging.