Search

Abstract This study aimed to elucidate the relationship between joint structures of the first tarsometatarsal and articular facet degeneration. A total of 100 feet from 50 cadavers were examined. The articular facets of the first metatarsal and medial cuneiform were categorized into four types based on the superior and inferior facets' separation, and the formation of the inferior lateral facet on the lateral plantar prominence: Type I, a single facet with no separation or inferior lateral facet; Type II-a, two facets with separation but no inferior lateral facet; Type II-b, two facets, no separation, but with an inferior lateral facet; Type III, three facets with separation and an inferior lateral facet. When both bone types matched, they were defined as Type I, Type II-a, Type II-b, and Type III joints, respectively; unmatched types were classified as Unpair joints. The severity of articular cartilage degeneration on both bones was assessed using a 5-point scale. The degeneration grade was compared among joint types. Type III joints exhibited significantly milder articular cartilage degeneration in medial cuneiform compared to Type II-a, II-b, Unpair joints. The formation of inferior lateral facet and separation of the superior and inferior facets might be crucial for the joint's stability.

Abstract Anterior ankle impingement syndrome (AAIS) has been reported to account for a high percentage of complications following ankle fracture surgery. The soft tissue etiology of AAIS is thought to be thickening and inflammation of the anterior ankle soft tissues intervening anteriorly at the tibiotalar joint, causing pain and functional limitation during dorsiflexion. However, the effects of anterior ankle soft tissue dynamics and stiffness on AAIS have yet to be clarified. This study aimed to determine the relationship between AAIS and the anterior ankle soft tissue thickness change ratio and shear modulus using ultrasonography (US). The participants were 20 patients with ankle joint fractures (AO classification A, B) who had undergone open reduction and internal fixation and 20 healthy adults. The evaluation periods were 3 months and 6 months postoperatively. US was used to delineate the tibialis anterior tendon, extensor hallucis longus tendon, and the extensor digitorum longus tendon over the talus and tibia on a long-axis image. Anterior ankle soft tissue thickness was measured as the shortest distance from the most convex part of the talus to the tendon directly above it. The Anterior ankle soft tissue thickness change ratio was determined by dividing the value at 0° dorsiflexion by the value at 10° plantarflexion. The same images as for the anterior soft tissue thickness measurement were drawn for the shear modulus measurement, and the average shear modulus (kPa) was calculated using shear-wave elastography. There was no significant difference in the thickness change ratio between the postoperative and healthy groups. Compared with the healthy group, the shear modulus was significantly higher at 3 and 6 months in the postoperative group (p

Abstract Background This study aimed to: (1) identify assessment methods that can detect greater ankle dorsiflexion range of motion (DROM) limitation in the injured limb; (2) determine whether differences in weightbearing measurements exist even in the absence of DROM limitations in the injured limb according to non-weightbearing measurements; and (3) examine associations between DROM in the weightbearing and non-weightbearing positions and compare those between a patient group with foot and ankle injuries and a healthy group. Methods Eighty-two patients with foot and ankle injuries (e.g., fractures, ligament and tendon injuries) and 49 healthy individuals participated in this study. Non-weightbearing DROM was measured under two different conditions: prone position with knee extended and prone position with knee flexed. Weightbearing DROM was measured as the tibia inclination angle (weightbearing angle) and distance between the big toe and wall (weightbearing distance) at maximum dorsiflexion. The effects of side (injured, uninjured) and measurement method on DROM in the patient groups were assessed using two-way repeated-measures ANOVA and t-tests. Pearson correlations between measurements were assessed. In addition, we analyzed whether patients without non-weightbearing DROM limitation (≤ 3 degrees) showed limitations in weightbearing DROM using t-tests with Bonferroni correction. Results DROM in patient groups differed significantly between legs with all measurement methods (all: P

Abstract Background The purpose of this study was to clarify the attachment types of the tibialis anterior tendon (TAT) in Japanese fixed cadavers and to determine the attachment site area in three dimensions. Methods We examined 100 feet from 50 Japanese cadavers. The TAT was classified according to differences in the number of fiber bundles as: Type I, with one fiber bundle; Type II, with two fiber bundles; and Type III, with three fiber bundles. The attachment site area of the TAT was measured using a three-dimensional scanner. Results Cases were Type II in 95% and Type III in 5%, with no cases of Type I identified. In Type II, mean attachment site areas were 85.2 ± 18.2 mm2 for the medial cuneiform bone (MCB) and 72.4 ± 19.0 mm2 for the first metatarsal bone (1 MB), showing a significantly larger area for MCB than for 1 MB. Conclusions These findings suggest the possibility of ethnic differences in TAT attachment types and suggest that TAT attachments in Japanese individuals are highly likely to be Type II, with rare cases of Type III. Accurate measurement of attachment site areas is possible with appropriate three-dimensional measurements.

BackgroundThis study aimed to determine changes in the muscle and tendon stiffness of the thigh and lower leg muscle-tendon units during the early follicular and early luteal phases, and check for possible relations between muscle and tendon stiffness in each phase.MethodsThe sample consisted of 15 female university students with regular menstrual cycles. The basal body temperature method, ovulation kit, and salivary estradiol concentration measurement were used to estimate the early follicular and early luteal phases. A portable digital palpation device measured muscle-tendon stiffness in the early follicular and early luteal phases. The measurement sites were the rectus femoris (RF), vastus medialis (VM), patellar tendon (PT), medial head of gastrocnemius muscle, soleus muscle, and Achilles tendon.ResultsNo statistically significant differences in the thigh and lower leg muscle-tendon unit stiffness were seen between the early follicular and early luteal phases. Significant positive correlations were found between the stiffness of the RF and PT (r = 0.608, p = 0.016) and between the VM and PT (r = 0.737, p = 0.002) during the early luteal phase.ConclusionThe present results suggest that the stiffness of leg muscle-tendon units of the anterior thigh and posterior lower leg do not change between the early follicular and early luteal phases and that tendons may be stiffer in those women who have stiffer anterior thigh muscles during the early luteal phase.

IntroductionCore stability is crucial for preventing and rehabilitating lumbar spine injuries. An external focus instruction using a paper balloon is an effective way to activate the trunk muscles. However, the degree of trunk and lower extremity muscle activation during single leg stance with external focus instruction using a paper balloon is unknown. This study aimed to investigate the core muscle involving activity in the trunk and lower extremities on both the support and non-support sides with or without using external focus instruction using a paper balloon during isometric single-leg stance.MethodsThirteen healthy males aged 20–28 years volunteered to take part in this study and performed a single leg stance task with and without an external focus instruction, pressing their non-supporting foot onto a paper balloon without crushing it. The participant's muscle electrical activity was recorded during the single leg task using surface EMG and intramuscular EMG for six trunk muscles (transversus abdominis, internal oblique, external oblique, rectus abdominis, multifidus, and lumbar erector spinae) and five lower extremity muscles (gluteus maximus, gluteus medius, adductor longus, rectus femoris, and biceps femoris)ResultsCompared to the normal single leg stance, the external focus instruction task using a paper balloon showed significantly increased transversus abdominis (p

Abstract This study aimed to investigate whether muscle synergy differs between swimmers with and without swimmer's shoulder in the butterfly technique. Muscle synergies, which can assess muscle coordination, were analyzed using surface electromyography. Twenty elite swimmers were included in this study (swimmer's shoulder: n = 8; control: n = 12). The motions involved in executing the butterfly technique were classified into the early pull-through, late pull-through, and recovery phases. Muscle synergy data analyzed using the nonnegative matrix factorization method were compared between the two groups. The swimming velocities were 1.66 ± 0.09 m・s −1 and 1.69 ± 0.06 m・s −1 for the control and swimmer's shoulder groups, respectively. Four muscle synergies in both groups were identified: synergy #1, which was involved in the early pull; synergy #2, involved in the late pull; synergy #3, involved in the early recovery; and synergy #4, involved in pre- and posthand entry. Compared to the control group, the swimmer's shoulder group had a small contribution from the pectoralis major (p = 0.032) and a high contribution from the rectus femoris during the early pull phase (p = 0.036). In the late pull phase, the contribution of the lower trapezius muscle in the swimmer's shoulder group was low (p = 0.033), while the contribution of the upper trapezius muscle in the pre- and postentry phases was high (p = 0.032). In the rehabilitation of athletes with swimmer's shoulder, it is therefore important to introduce targeted muscle rehabilitation in each phase.

Abstract Perturbation exercises enhance lower limb and trunk muscles, and adding swing perturbation while loading during exercise might improve muscle activation or strength. This study aimed to check variations in trunk and lower limb muscle activity during conventional isometric squats, and whether it will change with or without swing using the Hammerobics-synchronized squat method. Twelve healthy men participated in this study. Activities for the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, rectus femoris, biceps femoris long head, semitendinosus, gluteus maximus, multifidus, and internal oblique muscles were measured using surface electromyography during a Hammerobics-synchronized squat and conventional isometric squat. Muscle activities were statistically compared between squat methods. Hammerobics-synchronized squats significantly activated the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, semitendinosus, and multifidus muscles, in both phases, compared with the conventional isometric squats. The Hammerobics-synchronized squat exercise can be considered for trunk and foot stability exercise.

Abdominal bracing exercise is used to enhance all abdominal muscle activity. There are two methods of abdominal bracing— “activate the abdominal muscles without hollowing the lower abdomen” and “activate the abdominal muscles while inflating the lower abdomen”. Although the latter method is widely used in athletic fitness coaching, the electromyographic activities of the abdominal muscles in this method have not been measured yet. This study aimed to clarify the electromyographic activity of all abdominal muscles during abdominal bracing using the latter method of “activating the abdominal muscles while inflating the lower abdomen”. Thirteen healthy men (age: 22 ± 2 years) participated in this study. Transversus abdominis (TrA), internal oblique (IO), external oblique (EO), and rectus abdominis (RA) electromyography was recorded using an intramuscular fine wire and surface electrodes. The participants performed abdominal bracing and hollowing for 5 s (seconds) in six different positions. The electromyographic data during trials were calculated as a percentage of maximal voluntary isometric contraction (%MVIC). A two-way ANOVA was used to compare the %MVIC of each trunk muscle between abdominal bracing and hollowing among the six different positions. In TrA electromyography, there was no difference between abdominal bracing and hollowing. On the other hand, the activities during abdominal hollowing were significantly higher than those during abdominal bracing in IO and EO (p < 0.05). In RA, the activities during abdominal bracing were significantly higher than those during abdominal hollowing (p < 0.05). Abdominal bracing under the method of inflating the lower abdomen is not recommended for high activity of the IO and EO.

Psychological pressure during sports competition disturbs the ideal physical movement and causes injury. Baseball batting frequently causes trunk injuries. This study aimed to examine the influence of psychological pressure on the lumbar kinematics and trunk muscle activity during the baseball batting. Fourteen collegiate baseball players participated in this study. The participants performed bat swings under three different psychological conditions (non-pressure, pressure, and emphasized pressure). The lumbar kinematics and trunk muscle activity were measured during each bat swing. One- and two-way analyses of variance were performed to compare the lumbar kinematics and trunk muscle activity among different psychological pressure conditions. The lumbar flexion angle throughout the bat swing in the swing phase, from the moment of ground contact of the lead foot to the moment of ball contact, was significantly larger under the pressure and emphasized pressure conditions than under the non-pressure condition (P

Abstract Background Medial tibial stress syndrome is a common sports related injury. Altered foot kinematics can be a risk factor for the injury. Since foot segments can move independently, intersegment coordination is important for proper foot function. This study aimed to compare the foot intersegmental coordination pattern and single segment kinematics between female lacrosse players with and without a history of medial tibial stress syndrome during drop jump. Methods Twelve players with a medial tibial stress syndrome history and 12 players with no history were enrolled. Foot kinematics, including angle at landing and peak angle and excursion at the rearfoot, midfoot, and forefoot during single‐leg drop jumps were analysed. Each segment motion data from landing to leaping was time‐scaled to 100% to analyse the intersegmental coordination with a modified vector coding technique. Instant intersegmental coordination of every 1% was classified into four patterns (in‐phase, two segments rotate in the same direction with similar amplitudes; anti‐phase, two segments rotate in opposite directions; proximal phase, proximal segment dominantly rotates in the same direction compared to the distal segment; and distal phase, distal segment dominantly rotates in the same direction compared to the proximal segment). The percentage of intersegmental coordination pattern and kinematics in each segment were compared between the groups using the Student's t test. Results Groups with a history of medial stress syndrome showed a significantly higher percentage of proximal phase between the rearfoot and midfoot in the sagittal (Mean ± SD; history, 52.2 ± 17.9%, no history, 29.3 ± 16.7%; p = 0.004) and coronal planes (history, 40.3 ± 22.0%, no history, 15.9 ± 9.1%; p = 0.004). Dorsiflexion excursion (history, 34.5 ± 4.5°, no history, 29.6 ± 2.1°; p = 0.003) were significantly larger in a history of medial tibial stress syndrome group compared to no history group. Conclusions Rearfoot dominant motion pattern relative to the midfoot may be related to medial tibial stress syndrome. Intersegmental coordination analysis may be useful for detecting abnormal foot coordination patterns. Also, stabilization for the rearfoot may be required rather than the midfoot for intervention.

Improving the performance of underwater undulatory swimming (UUS) improves swimming time, so it is important to identify the pattern of muscle coordination in swimmers with fast UUS. This study aimed to identify muscular coordination in the trunk and lower limb during UUS in elite swimmers. Nine swimmers (aged 20 ± 2 years; height, 1.74 ± 0.03 m; weight, 73.0 ± 4.4 kg) participated in this study. Measurements were taken by electromyography of eight muscles: rectus abdominis (RA), internal abdominal muscle (IO), rectus femoris (RF), erector spinae (ES), multifidus (MF), tibialis anterior (TA), and thigh biceps (BF), and gastrocnemius (GS). For evaluation of muscle coordination, “muscle synergy” and “activation coefficient” were calculated using non-negative matrix factorization from electromyographic data. Kick frequency, kick amplitude, swim velocity, and kinematics of the pelvis were also calculated. Kick cycle was divided into two kick phases: downward kick (from the highest toe vertical coordinate to the lowest point) and upward kick (from the lowest point to the highest point). Kick frequency, kick amplitude, and swimming velocity were 1.9 ± 0.3 Hz, 0.45 ± 0.6 m, and 1.8 ± 0.2 m·s −1, respectively. The maximum backward pelvic tilt was 94.4 ± 4.5° and the minimum (forward) was 90.8 ± 5.7°. Three muscle synergy values were extracted from each swimmer during UUS: those involved in the transition from upward kick to downward kick (Synergy 1), downward kick (Synergy 2), and upward kick (Synergy 3). Synergy 1 involved mainly the RF, IO, and RA, which were activated during the turn from the upward to the downward phase. Synergy 2 involved mainly the MF, ES, and TA in the downward kick. Synergy 3 corresponded to the coordination of the BF and GS, which were active in the upward kick. In UUS by elite swimmers, both the upward kick and downward kick followed the trunk muscles involved in the pelvic forward–backward tilt movement, and lower limb muscles were activated. Muscle coordination based on pelvic forward-backward tilt during UUS is expected to contribute to the coaching field for elite swimmer development.

Objectives This study aimed to clarify the trends of injury occurrence in the Japan national swim team for 15 years and to evaluate the effectiveness of the lumbar injury prevention project. It also aimed to verify the incidence of swimming-related injuries among swimmers by sex, age and swimming style.Methods The target group comprised 488 swimmers who participated in the Olympics, Asian Games and Universiade from 2002 to 2016; we compiled data for the total number of injuries in each body part. The lumbar injury prevention project started in 2008 and included two components (deep trunk muscle exercises and evaluation of lumbar disc degeneration using MRI). We analysed the prevalence of lumbar injury before (2002–2008) and after (2009–2016) implementation of the lumbar injury prevention project by χ2 test. We compared age, sex and swim strokes between the injured and non-injured groups by χ2 test and unpaired t-test.Results The most common injury site was the lower back, followed by the shoulder and knee. The lumbar injury prevalence was significantly lower after implementation of the prevention project (23.5% vs 14.8%; p

Context: The range of shoulder rotation is associated with shoulder pain in young male and female swimmers. However, the association between shoulder pain and shoulder complex mobility of the scapulothoracic and acromioclavicular joints has not yet been examined. Moreover, shoulder pain occurs more frequently in females than in males, but only a few studies have examined the relationship between shoulder pain and sex as a risk factor. This study aims to determine the association between shoulder complex mobility and shoulder pain in young male and female swimmers. Design: Prospective cohort design. Methods: The participants were competitive swimmers (n = 76; 37 males and 39 females) with a mean age of 14 years in Japan. The shoulder rotation width, which was the index of shoulder complex mobility, shoulder internal and external rotation range, and middle finger distance of the back-scratch test were measured. An examiner regularly visited the swimming clubs to evaluate the development of shoulder pain and swimming distance. Logistic regression analysis was used to determine the physical characteristics related to the overall development of shoulder pain in both female and male swimmers. The cutoff value was calculated using receiver operating characteristic curves. Results: Sixteen participants, composed of 8 males and 8 females, developed shoulder pain. The overall swimming distance of the male (odds ratio [OR]: 1.0007, P = .01) and female (OR: 1.0018, P = .02) swimmers and the shoulder rotation width of the male (OR: 1.0952, P = .04) and female (OR: 0.888, P = .03) swimmers were identified as risk factors for shoulder pain. The cutoff value for swimming distance was 6000 m. Shoulder rotation width was more than 88 cm in males and <54 cm in females. Conclusions: Hypomobility and hypermobility of the shoulder complex were identified as risk factors for shoulder pain in male and female swimmers, respectively. [ABSTRACT FROM AUTHOR]

Context: The quadratus lumborum ( QL) is expected to contribute to segmental motor control ofthe lumbar spine to prevent low back pain. It has different layers (anterior [QL-a] and posterior [QL-p] layers), whose functional differences are becoming apparent. However, the difference between the QL-a and QL-p activities during bridge exercises utilized in rehabilitation is unclear. Objective : To compare QL - a and QL - p activities during bridge exercises . Design: Repeated-measurement design was used to assess electromyographic activity of trunk muscles recorded during 14 types of bridge exercises . Setting : University laboratory . Participants : A total of 13 healthy men with no history of lumbar spine disorders participated . Intervention. The participants performed 14 types of bridge exercises (3,3, and 8 types of side bridge, back bridge, and front bridge [FB], respectively ). Main Outcome Measures: Fine - wire electromyography was used for QL -a and QL - p activity measurements during bridge exercises . Results : Both QL - a and QLp showed the highest activity during the side bridge with hip abduction (47.3% [29.5%] and 43.0% [32.9%] maximal voluntary isometric contraction, respectively). The activity of the QL-a was significantly higher than that of the QL-p during back bridge with ipsilateral leg lift and FB elbow-toe with ipsilateral arm and contralateral leg lift (P < .05). With regard to the QL-p, the activity of the FB hand-knee with contralateral arm and ipsilateral leg lift, the FB elbow-knee with contralateral arm and ipsilateral leg lift, and the FB elbow-toe with contralateral arm and ipsilateral leg lift were significantly higher than that of the FB elbow -knee and FB elbow-toe (P <. 05 ). Conclusion: This study indicates different regional activities; the QL-a activated during the back bridge with ipsilateral leg lift and FB with ipsilateral arm lift, and the QL-p activated during the FB with ipsilateral leg lift. These results have implications for the rehabilitation of low back pain or lumbar scoliosis patients based on QL recruitment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Trunk muscle activity during isometric exercise is altered by external-focus instruction. OBJECTIVE: To check alterations in trunk muscle activity during side plank exercise both with and without instructions to refrain from crushing an item (external-focus instruction method). METHODS: Twenty-one healthy men aged 20–49 participated in this study. Ten trunk muscle activities were measured using surface electromyography during side plank exercises both with and without external-focus instruction. The unpaired t-test or Mann–Whitney U test was used to compare differences between exercise tasks and between sides. RESULTS: Side plank exercise with external-focus instruction increased activity of the upper trapezius, lower trapezius, latissimus dorsi, medial head of the triceps, and internal oblique on the supported side when compared with that without external-focus instruction (p < 0.05 for all). On the unsupported side, side plank exercise with external-focus instruction significantly increased activity of the upper trapezius, lower trapezius, latissimus dorsi, medial head of the triceps, clavicular part of the pectoralis major serratus anterior, external oblique, rectus abdominis, internal oblique, and multifidus when compared with that without external-focus instruction (p < 0.001 for all). CONCLUSIONS: Adding the external-focus instruction method to the conventional side plank exercise may be effective in increasing the trunk muscles’ activity. [ABSTRACT FROM AUTHOR]

This study aimed to clarify the changes in the activity of the trunk and lower limb muscles during 2000-m rowing. Ten male rowers performed a 2000-m race simulation on a rowing ergometer. Electromyography results of the abdominal muscles, back muscles, gluteus maximus (GMax), biceps femoris (BF), and rectus femoris (RF) were recorded. The electromyographic activity during the three strokes after the start (initial stage), at 1000m (middle stage), and before the end (final stage) were analyzed. From the handle position, the rowing motion was divided into five phases (early-drive, middle-drive, late-drive, early-recovery, and late-recovery). The peak activities of the abdominal muscles, back muscles, GMax, and BF in each stroke of the rowing motion were delayed at the middle and final stages compared to the initial stage (P < 0.05). The peak activity of the RF was observed in the late-drive phase at the initial stage, whereas a high RF activity was observed in the middle-drive phase at the middle and final stages (P < 0.05). Considering the results of the activity of the back muscles and RF, RF muscular endurance enhancement may lead to a decrease in the load on the back muscles and help prevent muscular low back pain in rowers. [ABSTRACT FROM AUTHOR]

Compared to back squat (BSQ), front squat (FSQ) exhibits a smaller anterior trunk tilt to avoid dropping a barbell held in front of the body, which may lead to increase trunk extension and lumbar lordosis. This study aimed to clarify the differences in the lumbar lordosis angle, anterior trunk tilt angle, and muscle activities of the lower limb and trunk between the FSQ and BSQ. Ten healthy men participated in this study. The participants performed parallel and full FSQ and BSQ. The SQ motion was recorded using three-dimensional motioncapture cameras, and divided into four phases. The lumbar lordosis angle, anterior trunk tilt angle, and lower limb and trunk muscles activity were analyzed. Independent t-tests were used to compare the minimum lumbar lordosis angle and maximum anterior trunk tilt angle between the FSQ and BSQ in each SQ depth. Two-way analysis of variances (barbell positions × phases) were used to compare the mean lumbar lordosis angle and each muscle activity in each phase between the FSQ and BSQ in each SQ depth. The lumbar lordosis angle was significantly larger during FSQ than during BSQ at the minimum value and the mean value in each phase, regardless of depths (P < 0.05). There were no significant differences in the maximum anterior trunk tilt angle and muscle activities of the lower limb and trunk between the FSQ and BSQ in both depths (P > 0.05). These results are the basis for proposing an appropriate SQ style using the FSQ and BSQ to prevent low back pain. [ABSTRACT FROM AUTHOR]

The purpose of this study was to clarify the influence of different postures on the activity of the shoulder girdle and lower back muscles while using a smartphone. Sixteen healthy male participants maintained two postures while using a smartphone: a good posture in which the tragus and acromion were closer to the vertical line passing through the greater trochanter, and a poor posture in which the tragus and acromion were farther from the vertical line passing through the greater trochanter. The target muscles were the rhomboid major (Rhom), upper trapezius, middle trapezius, lower trapezius (LT), lumbar erector spinae (LES), and lumbar multifidus (LMF). The activities of the Rhom and LT were significantly lower with poor posture than those with good posture. The activities of LES and LMF were significantly higher with poor posture than those with good posture. The results of this study indicated that poor posture was associated with hypoactivity of the shoulder girdle muscles and hyperactivity of the lower back muscles when compared with good posture. Poor posture for prolonged periods while using a smartphone would lead to malfunction of the shoulder girdle muscles and musculofascial lower back pain. [ABSTRACT FROM AUTHOR]