Minoru Okita

Effect of Ankle Disk Training Combined with Tactile Stimulation to the Leg and Foot on Functional Instability of the Ankle

Twenty-two university students with unilateral functional instability of the ankle participated in this study. They were randomly assigned to one of two experimental groups. Subjects in both groups were trained to stand on the affected limb on an ankle disk. In group 1, two pieces of 1-cm wide nonelastic adhesive tape were applied to the skin around the lateral malleolus from the distal third of the lower leg to the sole of the foot before the training sessions. Subjects in group 2 participated in the training sessions without the application of the adhesive tape. Training was performed for 10 minutes a day, five times per week, for a period of 10 weeks. Subjects were tested for postural sway while standing on the affected limb before, during, and after the training period. In group 1, postural sway values decreased significantly after 4 weeks compared with the pretraining performance, and they were within the normal range after not more than 6 weeks of training. In group 2, the values did not improve significantly compared with the pretraining performance until after 6 weeks of training, and they were not within the normal range until after 8 weeks of training. The findings suggest that the 2-week earlier correction of postural sway in group 1 was due to an increased afferent input from skin receptors that were stimulated by the traction of the adhesive tape.

Low‐level laser irradiation promotes the recovery of atrophied gastrocnemius skeletal muscle in rats

Low‐level laser (LLL) irradiation promotes proliferation of muscle satellite cells, angiogenesis and expression of growth factors. Satellite cells, angiogenesis and growth factors play important roles in the regeneration of muscle. The objective of this study was to examine the effect of LLL irradiation on rat gastrocnemius muscle recovering from disuse muscle atrophy. Eight‐week‐old rats were subjected to hindlimb suspension for 2 weeks, after which they were released and recovered. During the recovery period, rats underwent daily LLL irradiation (Ga–Al–As laser; 830 nm; 60 mW; total, 180 s) to the right gastrocnemius muscle through the skin. The untreated left gastrocnemius muscle served as the control. In conjunction with LLL irradiation, 5‐bromo‐2′‐deoxyuridine (BrdU) was injected subcutaneously to label the nuclei of proliferating cells. After 2 weeks, myofibre diameters of irradiated muscle increased in comparison with those of untreated muscle, but did not recover back to normal levels. Additionally, in the superficial region of the irradiated muscle, the number of capillaries and fibroblast growth factor levels exhibited significant elevation relative to those of untreated muscle. In the deep region of irradiated muscle, BrdU‐positive nuclei of satellite cells and/or myofibres increased significantly relative to those of the untreated muscle. The results of this study suggest that LLL irradiation can promote recovery from disuse muscle atrophy in association with proliferation of satellite cells and angiogenesis.

Effects of reduced joint mobility on sarcomere length, collagen fibril arrangement in the endomysium, and hyaluronan in rat soleus muscle.

Immobilization is often associated with a decrease in muscle elasticity. This condition is called muscle contracture, but the mechanism is not yet clear. We examined changes in ankle joint mobility, sarcomere length, collagen fibril arrangement in the endomysium, and hyaluronic acid (HYA) in muscular tissue 1, 2, 4, 8, and 12 weeks after immobilization of rat soleus muscles in shortened position. Ankle joint mobility decreased with the duration of immobilization. Sarcomere length had shortened 1week after immobilization, but did not show further change 2, 4, 8, and 12 weeks after immobilization. Collagen fibril arrangement in the endomysium 1 and 2 weeks after immobilization was longitudinal to the axis of the muscle fibers, whereas 4, 8, and 12 weeks after immobilization it was circumferential. HYA in muscular tissue had increased 1 week after immobilization but remained at the same level at weeks 2, 4, 8, and 12. Histochemically, HYA in the endomysium of immobilized muscular tissue was stained more strongly and widely than that in the control tissue. Increased HYA in muscular tissue may induce muscle stiffness, but the significance of how HYA is related to the mechanism of muscle contracture was not clear. The findings suggest that muscle contracture started 1 week after immobilization and increased with the length of immobilization. Consequently, muscle contracture is affected by the shortening muscle fibers during the early stage of immobilization, after which the collagen adapts by the fibril arrangement in the endomysium becoming more circumferential. This change in collagen fibril arrangement may cause advanced muscle contracture in the late stage of immobilization.

Effects of Therapeutic Ultrasound on Joint Mobility and Collagen Fibril Arrangement in the Endomysium of Immobilized Rat Soleus Muscle

This study examined effects of therapeutic ultrasound on joint mobility and collagen fibril arrangement in the endomysium of immobilized rat soleus muscle. Twenty-two male Wistar rats were divided randomly into control (n = 5) and experimental groups (n = 17). In the experimental group, bilateral ankle joints of each rat were fixed in full plantar flexion with a plaster cast over a 4-wk period. Five animals in the experimental group were immobilized throughout the 4-wk (immobilization group) period, whereas the remaining rats in the experimental group were randomly divided into the ultrasound (US, n = 6) and sham (n = 6) treatment groups. Under anesthesia, continuous ultrasonic energy (frequency, 1 MHz; intensity, 1.0 W/cm(2)) was delivered to the triceps surae muscle of the US group for 15 min per d, 6 d per wk over the 4-wk immobilization period. Ultrasonic energy was not delivered to the triceps surae muscle in sham animals; only the transducer head was moved. Ankle joint mobility on dorsiflexion in the immobilization, sham and US groups was significantly smaller than that of the control group, whereas in the US group, this parameter was significantly greater than in the immobilization and sham groups. Collagen fibril arrangement in the endomysium of the control and US groups was longitudinal to the axis of the muscle fibers; in contrast, it was circumferential in the immobilization and sham groups. Our findings revealed that joint immobilization induces decreased joint mobility and collagen fibril movement in the endomysium; furthermore, ultrasound treatment can prevent these changes. We hypothesized that therapeutic ultrasound during the immobilization process may inhibit deterioration of muscle contracture.

Immobilization-Induced Cartilage Degeneration Mediated Through Expression of Hypoxia-Inducible Factor-1α, Vascular Endothelial Growth Factor, and Chondromodulin-I

Immobilization results in thinning of the articular cartilage and cartilage degeneration, although the exact mechanisms are not clear yet. Hypoxia is thought to contribute to the degeneration of articular cartilage. We investigated the roles of hypoxia inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), and the newly cloned antiangiogenic factor, chondromodulin-I (ChM-1), in cartilage degeneration in immobilized joints. Male Wistar rats (n = 30, 12-week-old) were divided randomly into the control group (n = 10), immobilization group (n = 10), and continuous passive motion (CPM) group (n = 10). In the immobilization group, the ankle joints were fixed in full plantar flexion with plaster casts for 4 weeks. In the CPM group, the ankle casts were removed during the immobilization period and the ankle joints were subjected to CPM. Significant thinning of the articular cartilage was noted in the immobilization group but not in the control or CPM group. In the immobilized group, vascular channels were found in the area between the calcified cartilage zone and the subchondral bone. The densities of HIF-1α—and VEGF-immunostained cells were higher in the immobilized group than the other two groups. In contrast, low expression of ChM-1 was detected in the articular cartilage of the immobilized group compared with the control and CPM group. Our results showed that immobilization induces thinning of the articular cartilage and appearance of vascular channel, in areas with balanced expression of HIF-1α/VEGF and ChM-1.

Effects of Short Duration Stretching on Disuse Muscle Atrophy in Immobilized Rat Soleus Muscles

The purpose of this study was to determine whether short duration stretching is ameliorating for disuse muscle atrophy in immobilized rat soleus muscles. Eighteen male Wistar rats (age, 8 weeks; weight, 311.0 ± 35.6 g) were divided randomly into control (n=3) and experimental (n=15) groups. Bilateral ankles of each rat in the experimental group were fixed in full planter flexion with a plaster cast. After the experimental groups rats were immobilized for 4 weeks, animals were divided into three groups: immobilization alone (group I, n=3), stretch training for 30 min/day for 1 or 3 weeks after remobilization (group S, n=6), and spontaneous recovery (non stretch training) for 1 or 3 weeks after remobilization (group NS, n=6). At the end of the experimental periods, the soleus muscle was extracted from hindlimb, and the frozen sections were stained with myofibrillar adenosine triphosphatase. After 1 week of remobilization, the means of the muscle fiber diameters for type I fibers in group S had increased significantly compared with group NS, but those for type II fibers in group S did not significantly differ from that for group NS. After 3 weeks of remobilization, the means of the muscle fiber diameters for types I and II fibers in group S had increased significantly compared with group NS. No difference in the fiber type distribution were observed between the experimental group. Our findings suggest that short duration stretching induces recovery from disuse muscle atrophy after joint fixation.

Investigation and Macroscopic Anatomical Study of Referred Pain in Patients with Hip Disease

[Purpose] The aim of this study was to examine the incidence and patterns of referred pain in patients with hip disease, as well as the nerve distribution in the hip and knee joints of 2 cadavers. [Subjects and Methods] A total of 113 patients with hip joint disease were included in the investigation. The incidence of regional pain and referred pain patterns were evaluated before and after arthroplasty. Two cadavers were macroscopically observed to verify the nerve innervation of the hip and knee joints. [Results] Anterior knee pain was observed preoperatively in 13.3% (in resting) and 33.6% (in motion) of the patients, which was comparable with the incidence of greater trochanter pain. In addition, the preoperative incidence rates of knee pain in resting and motion markedly decreased postoperatively. Of note is the remarkable incidence of pain radiating to the ventral lower limb. An anteromedial innervation was determined in the cadavers by the articular branches of the obturator and femoral nerve, which supply small branches to the knee joints. [Conclusion] Our results suggest that the distribution of the incidence of pain among the patients with hip disease is diverse owing to the sensory distribution of the femoral and obturator nerves.

Laminin-induced autoimmune myositis in rats.

The present study aimed to examine if immunization with laminin causes myositis in rats and whether the pathologic findings mirror human polymyositis and dermatomyositis. Rats were immunized with an emulsion of laminin and complete Freunds adjuvant. As a result, muscle fiber necrosis with infiltrating macrophages was frequently observed and mononuclear cells were observed in the endomysium. These mononuclear cells were composed of CD4+ cells, CD8+ T cells, and macrophages. CD4+ cells and CD8+ T cells were mainly located in the endomysium, whereas a large number of macrophages were located in the endomysium and infiltrating muscle fibers. A small number of B cells, detected by immunohistochemical staining, were mainly located in the perimysium. The nonnecrotic muscle fiber to which CD4+ T cells, CD8+ T cells, and perforin+ cells adhered was negative for antimerosin and antidystrophin antibodies. Muscle fiber necrosis in rats immunized with laminin may occur after denaturation of basement membrane proteins. In conclusion, the immunization with laminin induces moderate to severe myositis. We suggest that laminin may be an important antigen for connective tissue diseases such as polymyositis and dermatomyositis.

Effects of a balance training program using a foam rubber pad in community-based older adults: a randomized controlled trial.

Background and Purpose:Exercise programs aimed at improving balance are effective in fall prevention for older adults. Guidelines indicate that unstable elements should be integrated in balance training with this population. Balance training on an unstable surface facilitates proprioception mediated by skin receptors in the soles of the feet and by mechanoreceptors in the joints and muscles. This randomized controlled trial examined whether balance training performed using a foam rubber pad was more beneficial than balance training performed on a stable flat surface in older adults. Methods:Older adults using Japanese community day centers once or twice per week were enrolled in this trial. In total, 93 participants were randomized to 1 of 3 groups: foam rubber exercise group (n = 32), stable surface exercise group (n = 31), and control group (n = 30). Participants in the foam rubber and stable surface exercise groups attended a 60-minute exercise class once a week for 4 months and followed a home-based exercise routine. Outcome measures were the following performance tests: the one-leg standing test (OLST), the chair standing test, the timed up-and-go test (TUGT), and the tandem-stance test (TST). These assessments were conducted before the intervention, and at 1, 2, 3, and 4 months after starting the intervention. Results:There were group × time interactions (P < 0.001) for all performance tests. The foam rubber exercise group showed significant improvements in the OLST, TST, and TUGT at 1 to 4 months compared with the control group (P < 0.02). The foam rubber exercise group also showed significant improvements in the OLST and TST at 2 and 3 months compared with the stable surface exercise group (P < 0.02). Within the foam rubber exercise group, the OLST, TUGT, and TST, at 1 to 4 months, were significantly improved compared with before the intervention (P < 0.01). Within the stable surface exercise group, the TUGT and TST, at 3 and 4 months, were significantly improved compared with before the intervention (P < 0.01). Conclusions:This study confirms that balance training in older adults performed using a foam rubber pad is effective for improving balance ability, and that this improvement occurs 2 months earlier compared with balance training performed on a stable surface. These findings suggest that balance training performed using a foam rubber pad is beneficial to clients and service providers because the programs improve physical functioning with a reduced number of exercise sessions.

Effect of Immobilization on Insoluble Collagen Concentration and Type I and Type III Collagen Isoforms of Rat Soleus Muscle.

Immobilization is often associated with decreased muscle elasticity. This condition is known as muscle contracture; however, the mechanism remains unclear. The purpose of this study was to clarify the mechanism governing muscle contracture in rat soleus muscle by identifying changes in ankle joint mobility, insoluble collagen concentration and type I and type III collagen isoforms following 1- and 3-week immobilizations. Following a 1-week immobilization, range of motion (ROM) of dorsiflexion declined to 90% of the control value; additionally, ROM dropped to 67.5% of the control value after a 3-week immobilization. This finding suggested that ankle joint mobility decreases in conjunction with extended periods of immobilization. Insoluble collagen concentration in soleus muscles, which was unchanged after 1 week of immobilization, increased 3 weeks after immobilization. These results may be indicative of collagen fibers with strong intermolecular cross-links contained in the muscle was made increased relatively by 3 weeks of immobilization. Therefore, the change in intermolecular cross-links may be significant in terms of progress of muscle contracture with longer periods of immobilization. On the other hand, the ratio of type III to type I collagen isoforms in muscular tissue increased following a 1-week immobilization; moreover, this ratio remained constant after 3 weeks of immobilization. These data suggested that muscle immobilization may induce type III collagen isoform expression. The increase in the ratio of type III to type I collagen isoforms do not change in parallel with the increase in the limitation in ROM; however, this phenomenon probably is not closely related to the progress of muscle contracture. The change of collagen isoform in immobilized muscle may be involved in the mechanism governing the progression of muscle fibrosis.