Effects of abdominal hollowing and bracing on each intervertebral angle during quadruped upper and lower extremity lift: Three-dimensional motion analysis of the spine.

To investigate the effects of intentionally minimizing spinal motion and abdominal muscle contractions on intervertebral angles during quadruped upper and lower extremity lift (QULEL). Fifteen healthy men performed the QULEL under four conditions: without any special instructions (basic), with the intention to minimize spinal motion (intentional), with abdominal bracing (bracing), and with abdominal hollowing (hollowing). Each intervertebral angle was calculated from the local coordinate system using the marker data obtained from a motion capture system. Shear moduli, as indicators of the activities of the right transversus abdominis (TrA), internal and external oblique, and rectus abdominis muscles, were assessed using shear wave elastography during QULEL. One-way repeated-measures analysis of variance and multiple comparisons among conditions were used to compare each shear modulus of the abdominal muscle and the changes in thoracic kyphosis (Th1-12), lumbar lordosis (L1-5), and lumbar intervertebral angles from the quadruped position to QULEL. The significance level was set at P < 0.05. Changes in lumbar lordosis and L2/L3 and L3/L4 extension angles were significantly lower under hollowing than under other conditions (effect size ηG2: lumbar lordosis, 0.068; L2/L3, 0.072; L3/L4, 0.043). The change in the L1/L2 extension angle significantly decreased in bracing and hollowing compared with the basic (ηG2 = 0.070). Only the TrA shear modulus significantly increased in bracing and hollowing compared with the basic (ηG2 = 0.146). Abdominal hollowing during the QULEL increased TrA activity and suppressed lumbar extension, except at L4/L5, and may be more effective as a rehabilitation exercise for controlling spinal motion.

Early Recovery of Physical Function After Total Hip Arthroplasty in a Patient With Osteopetrosis: A Case Report.

Osteopetrosis is an uncommon and inherited disorder. Some disease-specific characteristics, such as diffuse osteosclerosis and a high incidence of fractures, may potentially affect postoperative rehabilitation. This report presents a case of successful rehabilitation early after total hip arthroplasty for osteopetrosis. A 56-year-old Japanese man, who was diagnosed with osteopetrosis at the age of 11, underwent total hip arthroplasty in the right hip. Full weight-bearing was allowed on the day after the operation; the postoperative rehabilitation program was proceeded based on a standard program as done after total hip arthroplasty for osteoarthritis. A shoe lift in the left leg was used in supervised walking training to correct the imbalanced alignment due to leg length discrepancy. The patient could walk independently with a cane 17 days after the operation. Three weeks after the operation, the patient demonstrated comfortable and maximal walking speed of 1.11 and 1.34 m/s, respectively, and maximal hip abductor muscle strength of 3.96 kgfï½¥m, both of which were better than those before the operation. There were no adverse events during the postoperative rehabilitation course. These findings suggest the safety and efficacy of standard rehabilitation programs after total hip arthroplasty even in individuals with osteopetrosis. In addition, it may be important to consider the whole-body condition in the rehabilitation of individuals with osteopetrosis.

Compensation strategy of shoulder synergist muscles is not stereotypical in patients with rotator cuff repair.

Rotator cuff tear is a common shoulder injury that causes shoulder dysfunction and pain. Although surgical repair is the primary treatment for rotator cuff tear, it is well recognized that impaired force exertion of muscles connecting to the involved tendon and subsequent complemental change in the force exertion of synergist muscles persist even after repair. This study aimed to identify the compensation strategy of shoulder abductors by examining how synergist muscles respond to supraspinatus (SSP) muscle force deficit in patients with rotator cuff repair. Muscle shear modulus, an index of muscle force, was assessed for SSP, infraspinatus, upper trapezius, and middle deltoid muscles in repaired and contralateral control shoulders of 15 patients with unilateral tendon repair of the SSP muscle using ultrasound shear wave elastography while the patients passively or actively held their arm in shoulder abduction. In the repaired shoulder, the shear modulus of the SSP muscle declined, whereas that of other synergist muscles did not differ relative to that of the control. To find the association between the affected SSP and each of the synergist muscles, a regression analysis was used to assess the shear moduli at the population level. However, no association was observed between them. At the individual level, there was a tendency of variation among patients with regard to a specific muscle whose shear modulus complementarily increased. These results suggest that the compensation strategy for SSP muscle force deficit varies among individuals, being nonstereotypical in patients with rotator cuff injury.

Changes in echo intensity of the gastrocnemius muscle with passive ankle dorsiflexion: can echo intensity be used to assess muscle elongation?

Introduction: While shear modulus has been used as an index of muscle elongation, high costs prevent its general adoption. A more general indicator that can quantify muscle elongation non-invasively is needed to develop effective methods for stretching each muscle. The purpose of this study was to determine whether the echo intensity of the muscle changes with muscle elongation compared with the shear modulus. Methods: Sixteen healthy males (24.1 ± 2.8 years) participated in the study. Shear modulus and echo intensity of the medial gastrocnemius were assessed at 20° and 10° of ankle plantar-flexion, and 0°, 10°, and 20° of ankle dorsiflexion (presented as -20°, -10°, and 0°, +10°, +20°, respectively). Shear modulus was measured using ultrasound shear wave elastography. The echo intensity was quantified using the average grayscale value of a given region of interest (RoI) in longitudinal and transverse B-mode images. Grayscale analysis was performed using two RoIs: one which included as much of the muscle as possible (maximum RoI), and a rectangular one whose size and depth was identical for all images (rectangular RoI). Pearson's correlation coefficients between either the shear modulus or echo intensity and the ankle angle and between the echo intensity and shear modulus were calculated separately for each participant. Results: Average Pearson's correlation coefficient between shear modulus and ankle angle of the participants was 0.904. The average Pearson's correlation coefficients between the echo intensity and ankle angle were estimated to be 0.797 and 0.222 for the maximum RoI and 0.698 and 0.323 for the rectangular RoI in the longitudinal and transverse images, respectively. The average Pearson's correlation coefficients between the echo intensity and shear modulus were 0.684 and 0.514 for the maximum RoI, and 0.611 and 0.409 for rectangular RoI in the longitudinal and transverse images, respectively. Discussion: The results indicate that the echo intensity in the longitudinal image of the gastrocnemius, especially when assessed using the maximum RoI, increased with muscle elongation by passive ankle dorsiflexion. Therefore, assessment of the echo intensity using the maximum RoI in the longitudinal image might be useful for quantifying the muscle elongation.

Mechanical characteristic of supraspinatus muscle changes independent of its size and intramuscular fat in patient with rotator cuff repair.

PURPOSE: This study aimed i) to investigate the mechanical, morphological, and compositional characteristics of the supraspinatus muscle after rotator cuff repair by using ultrasound shear wave elastography (SWE) and B-mode imaging, and ii) to determine whether the morphological or compositional characteristics are associated with the mechanical characteristic of the supraspinatus during contraction. METHODS: Using SWE and B-mode imaging, active and passive shear moduli, muscle thickness, and echo intensity of the supraspinatus were measured from the repaired and contralateral control shoulders of 22 patients with rotator cuff repair. The shear modulus, muscle thickness, and echo intensity were compared between the repaired and control shoulders. The association between the active shear modulus and the other variables was determined. RESULTS: While the active and passive shear moduli were lower in the repaired shoulder compared to the control, the muscle thickness and echo intensity did not vary between them. Interestingly, the passive shear modulus was positively correlated with the active shear modulus only in the control shoulder. CONCLUSION: The mechanical characteristic of supraspinatus remains impaired, even without degenerative changes in the morphological and compositional characteristics after rotator cuff repair. Furthermore, the association between contractile and elastic characteristics in the supraspinatus was deteriorated in control shoulder.

Efficacy of rehabilitation initiated in the early phase after simultaneous deceased donor liver and kidney transplantation: A case report.

RATIONALE: The purpose of this case report is to describe a case of successful early rehabilitation intervention for simultaneous liver and kidney transplantation (SLKT). PATIENT CONCERNS: A 51-year-old Japanese man was diagnosed with Caroli disease 27 years ago. Hemodialysis was introduced due to end-stage renal disease 17 years ago. DIAGNOSES: After successful SLKT, the patient was extubated on postoperative day (POD) 1, liberated from dialysis on POD 4, and discharged from the intensive care unit on POD 9. INTERVENTIONS: Supervised rehabilitation was started on POD 2, and the patient was able to walk 100 m on POD 9. Electrical muscle stimulation therapy was started to improve muscle weakness in both legs on POD 16, and aerobic exercise using a cycle-ergometer was started on POD 24. OUTCOMES: The 6-minute walking distance improved from 324 m on POD 14 to 501 m on POD 28. The patient could walk 4000 to 5000 steps per day at hospital discharge, and was discharged home on POD 32. There were no adverse events, including worsening hepatic or renal function, during the rehabilitation period. One month after discharge, the patient was able to perform 30 to 40 minutes of aerobic exercise every day, and returned to work 5 months after discharge. LESSONS: This case shows that early rehabilitation intervention immediately after SLKT safely and rapidly improved physical performance without adverse events. The results in the present case suggest that regular physical assessment and appropriate interventions with a variety of exercise modalities can contribute to improved physical performance in SLKT patients.

Effects of Low-Intensity Torque-Matched Isometric Training at Long and Short Muscle Lengths of the Hamstrings on Muscle Strength and Hypertrophy: A Randomized Controlled Study.

ABSTRACT: Nakao, S, Ikezoe, T, Taniguchi, M, Motomura, Y, Hirono, T, Nojiri, S, Hayashi, R, Tanaka, H, and Ichihashi, N. Effects of low-intensity torque-matched isometric training at long and short muscle lengths of the hamstrings on muscle strength and hypertrophy: A randomized controlled study. J Strength Cond Res 37(10): 1978-1984, 2023-This study investigated the effects of low-intensity torque-matched isometric training on muscle hypertrophy and strengthening at long (LL) and short muscle lengths (SL). Twenty-eight young subjects completed an 8-week hamstring isometric training program (30% of maximal voluntary contraction (MVC) × 5 s × 20 repetitions × 5 sets × 3 times/week) at 30° knee flexion (LL) or 90° knee flexion (SL). The cross-sectional area (CSA) of the hamstrings and MVC were measured before and after the intervention. The active torque because of muscle contraction was calculated by subtracting the passive torque at rest from the total torque (30% MVC). The active torque was significantly lower in the LL training group than in the SL training group (p < 0.01), whereas there was no between-group difference in total torque during training. For CSA and MVC at 30° knee flexion, the split-plot analysis of variance (ANOVA) showed no significant time × group interaction; however, it did show a significant main effect of time (p < 0.05), indicating a significant increase after training intervention. As for MVC at 90° knee flexion, there was a significant time × group interaction (p < 0.05) and a significant simple main effect of time in both the LL (p < 0.01; Cohen's d effect size [ES] = 0.36) and SL (p < 0.01; ES = 0.64) training groups. Therefore, low-intensity isometric training at LL can induce hypertrophy and strengthening, even in cases where the active torque production is lower than that at SL, whereas the training at SL may be more effective for muscle strengthening at SL.

Properties of the iliotibial band and their relationships with gait parameters among patients with knee osteoarthritis.

This study aimed to determine the thickness and stiffness of the iliotibial band (ITB) in patients with knee osteoarthritis (KOA) and to identify the gait parameters that are associated with ITB properties. Eighteen female patients with radiographically diagnosed medial KOA and knee pain (age: 69.7 ± 5.9 years, body mass index: 23.0 ± 3.1 kg/m2 ) and 22 age-matched female individuals without knee pain (age: 69.1 ± 7.0 years, body mass index: 21.6 ± 3.6 kg/m2 ) were included. Shear wave elastography images were obtained at the height of the proximal pole of the patella with the participants in the supine position, and the ITB thickness and shear wave velocity, which is a surrogate measure of stiffness, were calculated. In patients with KOA, the knee and hip joint angles and moments during walking were calculated using a motion analysis system. The shear wave velocity was significantly higher in patients with KOA than in asymptomatic adults (11.3 ± 1.0 vs. 10.0 ± 1.8 m/s, respectively; p = 0.010); however, the thickness did not differ between them (2.1 ± 0.3 vs. 2.0 ± 0.3 mm, respectively; p = 0.705). The time-integral value of the knee adduction moment (ß = 0.507, p = 0.032) and maximum value of the hip flexion moment (ß = 0.498, p = 0.036) were associated with the shear wave velocity. Meanwhile, no parameters were associated with the thickness. The ITB was stiffer in patients with KOA than in asymptomatic adults; such a stiffer ITB was associated with greater knee adduction and hip flexion moments during walking. Clinical Significance: Greater mechanical loading was associated with a stiffer ITB in patients with KOA.

Properties of triceps surae and Achilles tendon in forefoot and non-forefoot strike runners.

BACKGROUND: The purpose of this study was to compare the properties of the triceps surae and Achilles tendon of forefoot strike runners and non-forefoot strike runners. METHODS: Fourteen male college forefoot strike runners and 11 non-forefoot strike runners participated in this study. The shear elastic moduli and cross-sectional areas of the medial and lateral gastrocnemius, soleus, and Achilles tendon were measured. Passive ankle joint stiffness, maximum voluntary isometric contraction on plantar flexion and Rebound Jump Index were also measured. RESULTS: Forefoot strike runners had higher shear elastic moduli of the medial and lateral gastrocnemius, higher passive ankle joint stiffness, higher Rebound Jump Index, and greater cross-sectional area of the gastrocnemius and Achilles tendon than non-forefoot strike runners. CONCLUSIONS: These findings suggest that forefoot strike runners have different mechanical properties in the gastrocnemius muscles, and different morphological properties in the Achilles tendon and gastrocnemius muscles, compared with non-forefoot strike runners.

Relationship between individual forces of each quadriceps head during low-load knee extension and cartilage thickness and knee pain in women with knee osteoarthritis.

BACKGROUND: This study aimed to clarify the individual forces of each quadriceps head during low-load contractions and to determine the associations between individual muscle force and cartilage thickness and symptoms in female knee osteoarthritis patients. METHODS: Twenty-two women with painful knee osteoarthritis and 15 asymptomatic age-matched women (control group) participated in this cross-sectional study. Maximal knee extension strength and the cross-sectional area of each quadriceps muscle were measured. Shear modulus was calculated for each muscle during 20-Nm torque production by shear-wave elastography. Muscle force index was defined as the product of the cross-sectional area and shear modulus. Medial femur cartilage thickness was measured using an ultrasound B-mode image. Knee pain during gait was evaluated using a Numerical Rating Scale. Muscle force index, cross-sectional area, and maximal knee extension strength, which were defined as muscle functions, were compared between groups using the unpaired t-test. Correlation coefficients were calculated using muscle function, cartilage thickness, or pain. FINDINGS: Maximal strength and vastus lateralis force index were smaller in the knee osteoarthritis group than in the control group (p < 0.001 and p = 0.005, respectively). In the knee osteoarthritis group, vastus medialis and vastus lateralis force indexes were positively correlated with cartilage thickness (r = 0.57 and r = 0.45, respectively), whereas the rectus femoris force index was negatively correlated with cartilage thickness (r = -0.45). The vastus lateralis force index was negatively correlated with knee pain (ρ = -0.56). INTERPRETATION: Vasti force indices were positively associated with cartilage thickness; however, rectus femoris index was negatively associated in female patients with knee osteoarthritis.

Regional differential stretching of the pectoralis major muscle: An ultrasound elastography study.

Pectoralis major (PMa) muscle injuries are becoming more prevalent, and their incidence differs among the PMa regions, i.e., the clavicular, sternal, and abdominal regions. Therefore, identifying the position for effectively lengthening each PMa region is critical in preventing PMa injuries. The purpose of this study was to determine the effective stretching position for each PMa region through shear wave elastography, which can indirectly assess individual muscle lengthening. Fifteen men participated in this study. Twelve stretching positions were compounded with shoulder abductions (45°, 90°, and 135°), pelvic rotation (with or without), shoulder external rotation (with or without), and shoulder horizontal abductions. The shear modulus of each PMa region was measured through shear wave elastography in the stretching positions mentioned above. At the clavicular region, the shear modulus was higher for three stretching positions: shoulder horizontal abduction at 45° abduction during pelvic rotation and shoulder external rotation, shoulder horizontal abduction at 90° abduction, and shoulder horizontal abduction at 90° abduction while considering shoulder external rotation. For the sternal region, the shear modulus was higher in two stretching positions: shoulder horizontal abduction at 90° abduction while adding external rotation, and combination of pelvic rotation and external rotation. For the abdominal region, the shear modulus was higher in the shoulder horizontal abduction at 135° abduction with pelvic and external rotation. These results indicated that the effective stretching position was different for each PMa region.

Acute effects of repetitive peripheral magnetic stimulation following low-intensity isometric exercise on muscle swelling for selective muscle in healthy young men.

Repetitive peripheral magnetic stimulation (rPMS) is a non-invasive stimulator that can induce strong muscle contraction in selective regions. This study aimed to measure acute changes in skeletal muscle thickness induced by rPMS following a low-intensity exercise. Fifteen healthy young men performed an isometric knee extensor exercise at 30% of maximum strength consisting of three sets of 10 contractions on their dominant leg. rPMS was then applied on the vastus lateralis (VL) at the maximum intensity of the rPMS device. Muscle thicknesses of the rectus femoris (RF) and VL were measured using an ultrasound device and were compared among baseline, post-exercise, and post-rPMS. There were significant increases in muscle thickness of both the RF and VL post-exercise compared with baseline values (RF: baseline; 24.7 ± 2.4, post-exercise; 25.3 ± 2.4 mm, p = .034, VL: baseline; 27.0 ± 2.8, post-exercise; 27.4 ± 2.8 mm, p = .006). Compared with post-exercise, there was a significant increase post-rPMS in only the VL (VL: post-rPMS; 28.3 ± 2.9 mm, p = .002). These findings suggest that low-intensity isometric exercise can induce acute increases in muscle thickness (muscle swelling) in synergist muscles, and rPMS following exercise can induce further acute muscle swelling via repetitive muscle contraction.

Static stretching time required to reduce iliacus muscle stiffness.

Static stretching (SS) is an effective intervention to reduce muscle stiffness and is also performed for the iliopsoas muscle. The iliopsoas muscle consists of the iliacus and psoas major muscles, among which the former has a greater physiological cross-sectional area and hip flexion moment arm. Static stretching time required to reduce muscle stiffness can differ among muscles, and the required time for the iliacus muscle remains unclear. The purpose of this study was to investigate the time required to reduce iliacus muscle stiffness. Twenty-six healthy men participated in this study. A 1-min hip extension SS was performed five times. Shear elastic modulus, an index of muscle stiffness, of the iliacus muscle was measured using ultrasonic shear wave elastography before SS and immediately after each SS. One-way repeated analysis of variance showed a statistical effect of time on the shear elastic modulus. A paired t-test with Holm adjustment revealed that the shear elastic moduli after 1-5 SS were statistically lower than that before SS. In addition, the shear elastic modulus after 5 SS was statistically lower than that after 1 SS. The results suggested that the stiffness of the iliacus muscle decreased with 1-min SS and further decreased with 5-min SS.

Muscle size-scaled shear elastic modulus: A muscle force index independent of maximal voluntary contraction, assessed during elbow extension.

Shear elastic modulus (G) can differ among individuals due to muscle size and other factors, even for constant muscle force. Inter-individual comparisons of G usually require normalization by maximal voluntary contraction (MVC), but MVC procedures may not be appropriate for certain clinical populations including those presenting with pain or other compromised functionality. This study aimed to test whether muscle size-scaled G, which does not require MVC testing, would yield stronger correlation with absolute torque than unscaled G. Twelve-healthy males performed isometric elbow extension across a range of torque magnitudes (from 5 Nm until 60% MVC). G of the triceps brachii was measured using shear wave elastography during each trial. Cross-sectional area (CSA) and muscle thickness (MT) of the triceps brachii were measured at rest. Scaled G was calculated as a product of G and CSA or MT ("G-CSA" and "G-MT", respectively). Within-individual linear regressions were conducted between absolute torque and the three force indicator variables. The regression slopes' coefficient of variation (CV) was calculated for each indicator across individuals. Between-individual correlation coefficients were calculated, after pooling all data across individuals into a single regression analysis for each indicator. Linear regression found that inter-individual slope variation increased in the following order: G-CSA, G-MT, and unscaled G (CV = 0.15, 0.18, and 0.29, respectively). Pooled-individual correlation coefficients were significantly higher in G-CSA and G-MT than in unscaled G (r = 0.948, 0.924, and r = 0.783, respectively). These results suggest that muscle size-scaled G may be more appropriate than unscaled G when comparing shear moduli across individuals.

Effect of static stretching with different rest intervals on muscle stiffness.

The aim of the study was to investigate the effect of static stretching (SS) with different rest intervals on muscle stiffness. Fifteen healthy males participated in the study. Four bouts of thirty-second SS for the gastrocnemii were performed at the maximal dorsiflexion using dynamometer with two different rest intervals between stretches, namely 0 s (R0) and 30 s (R30). Each participant underwent both stretching protocols at least 48 h apart in a random order. Between each bout of SS, the ankle was moved to 20°-plantar-flexion in 3 s, held for each rest interval time, and then returned to the stretching position in 3 s. The shear elastic modulus of the medial gastrocnemius was measured before (PRE) and immediately after (POST) four bouts of SS to assess muscle stiffness of the medial gastrocnemius. Two-way repeated measures analysis of variance (protocol × time) indicated a significant interaction effect on the shear elastic modulus. The shear elastic modulus significantly decreased after SS in both protocols [R0, PRE: 11.5 ±â€¯3.3 kPa, POST: 10.0 ±â€¯2.6 kPa, amount of change: 1.6 ±â€¯0.9 kPa (13.0 ±â€¯5.2%); R30, PRE: 11.0 ±â€¯2.8 kPa, POST: 10.2 ±â€¯2.1 kPa, amount of change: 0.8 ±â€¯1.3 kPa (6.0 ±â€¯10.4%)]. Furthermore, the SS with 0-s rest interval induced greater decrease in shear elastic modulus when compared to SS with 30-s rest interval (p = 0.023). Thus, when performing SS to decrease muscle stiffness, rest intervals between stretches should be minimized.