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BACKGROUND: The flexor-pronator muscles (FPM) and their common tendon (CT) are essential in protecting the medial ulnar collateral ligament against elbow valgus stress during pitching. This study aimed to investigate the effect of repetitive pitching on FPM strength and CT stiffness. METHODS: Fifteen healthy males (mean age: 21.8 ± 1.3-years-old) with over 5 years of baseball experience performed a series of 100 full-effort fastball pitches. We measured grip and isolated digital flexion strength of the second, third, and fourth digits before and after the pitching task. The decline in muscle strength was determined using the rate of change in muscle strength after pitching relative to that before. CT stiffness was measured using a hand-held myotonometer device at rest and during grip motion at 50% maximum voluntary contraction. The increase in CT stiffness during grip motion relative to rest was calculated as the augmentation rate of CT stiffness. Statistical analyses were performed to compare the changes in grip strength, digital flexion strength, and CT stiffness due to pitching. Additionally, the reduction rate of muscle strength was compared among various strength variables. Correlation coefficients were used to evaluate the relationships between the augmentation rate of CT stiffness after pitching and the reduction rate in any muscle strength. RESULTS: Grip and isolated digital flexion strengths decreased significantly after pitching (P < 0.01). The decline in muscle strength was significantly higher for all isolated digital strengths than that for grip strength (P < 0.05). CT stiffness was augmented with grip motion compared to that at rest pre- and post-pitching (P < 0.001). However, no change in CT stiffness due to pitching was observed, regardless of the grip motion (P > 0.05). Additionally, a lower augmentation rate of CT stiffness after pitching was moderately associated with the greater reduction rate of the second digital flexion strength (r = 0.607, P = 0.016) without other relationships. CONCLUSION: This study found reduced grip and digital flexion strength after pitching; with no change in CT stiffness. However, given the consequences of correlation analyses, individuals with a more prominent reduction in second digital flexion strength due to pitching were impaired in CT stiffness augmentation after pitching. Digital flexion strength represents the strength of the flexor digitorum superficial; therefore, this study suggests that forearm FPM, particularly the second digit of the flexor digitorum superficial, is an important factor for enhancing CT stiffness.
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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.
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Cadáver , Humanos , Femenino , Masculino , Anciano , Persona de Mediana Edad , Anciano de 80 o más Años , Cartílago Articular/patología , Huesos Metatarsianos/patología , Huesos Metatarsianos/anatomía & histología , Articulaciones Tarsianas/patología , Articulaciones Tarsianas/anatomía & histología , Articulaciones del Pie/patologíaRESUMEN
PURPOSE: The suprapatellar bursa is located in the proximal deep layer of the patella and is thought to reduce tissue friction by changing from a single-membrane structure to a double-membrane structure during knee joint motion. However, the dynamics of the suprapatellar bursa have only been inferred from positional relationships, and the actual dynamics have not been confirmed. METHODS: Dynamics of the suprapatellar bursa during knee joint motion were observed in eight knees of four Thiel-fixed cadavers and the angle at which the bursa begins to show a double membrane was revealed. The flexion angles of knee joints were measured when the double-membrane structure of the suprapatellar bursa began to appear during knee joint extension. RESULTS: The suprapatellar bursa changes from a single membrane to a double-membrane structure at 91 ± 4° of flexion, when the knee joint is moved from a flexed position to an extended position. CONCLUSION: The suprapatellar bursa may be involved in limitations to knee joint range of motion and pain at an angle of approximately 90°. Further studies are needed to verify whether the same dynamics are observed in living subjects.
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Bolsa Sinovial , Cadáver , Articulación de la Rodilla , Rango del Movimiento Articular , Humanos , Rango del Movimiento Articular/fisiología , Articulación de la Rodilla/anatomía & histología , Articulación de la Rodilla/fisiología , Bolsa Sinovial/anatomía & histología , Masculino , Femenino , Anciano , Anciano de 80 o más Años , Rótula/anatomía & histología , Rótula/fisiología , Fenómenos BiomecánicosRESUMEN
This study explored the relationship between the morphological characteristics of the first tarsometatarsal ligaments and fibularis longus (FL) and the severity of articular cartilage degeneration in the first tarsometatarsal joint. Sixty legs from 30 cadavers were examined. The plantar, dorsal, and medial first tarsometatarsal ligaments were classified by fiber bundle number, and their morphological characteristics (fiber bundle length, width, thickness) were measured. The FL was categorized by its continuity with the plantar first tarsometatarsal ligament (PTML): Type A, connection with the PTML only on the first metatarsal; Type B, connection along the entire PTML; and Type C, no connection with the PTML. The severity of articular cartilage degeneration was assessed in four stages. No significant differences in cartilage degeneration among ligament types were found. Negative correlations were observed between the fiber bundle width and thickness of the PTML and the severity of cartilage degeneration. FL was classified as Type A in 68%, Type B in 27%, and Type C in 5% of feet. The fiber bundle thickness of the PTML in Type B was greater than in other types. Our findings suggest that smaller fiber bundle width and thickness in the PTML may be associated with severe cartilage degeneration. The FL had continuity with the PTML in 95% of feet and could enhance the mechanical strength of the PTML in Type B feet.
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Background: This 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. Methods: The 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. Results: No 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. Conclusion: The 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.
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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 < 0.01). The shear elastic modulus at 6-month postoperative group was significantly lower than at 3-month postoperative group (p < 0.01). Anterior ankle joint soft tissue stiffness may increase after surgery for an ankle fracture.
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Fracturas de Tobillo , Articulación del Tobillo , Adulto , Humanos , Articulación del Tobillo/diagnóstico por imagen , Articulación del Tobillo/cirugía , Tobillo , Fracturas de Tobillo/diagnóstico por imagen , Fracturas de Tobillo/cirugía , Tibia , Músculo EsqueléticoRESUMEN
The aim of this study was to clarify the effects of transcutaneous auricular vagus nerve stimulation (taVNS) to the left cymba concha on the pain perception using nociceptive withdrawal reflex (NWR), which is known to be associated with chronic pain, and to investigate whether there is a relationship between taVNS-induced suppression of the NWR and parasympathetic activation. We applied either 3.0 mA, 100 Hz taVNS for 120 s on the left cymba concha (taVNS condition) or the left earlobe (Sham condition) for 20 healthy adults. NWR threshold was measured before (Baseline), immediately after (Post 0), 10 min (Post 10) and 30 min after (Post 30) stimulation. The NWR threshold was obtained from biceps femoris muscle by applying electrical stimulation to the sural nerve. During taVNS, electrocardiogram was recorded, and changes in autonomic nervous activity measured by heart rate variability (HRV) were analyzed. We found that the NWR thresholds at Post 10 and Post 30 increased compared with baseline in the taVNS group (10 min after: p = .008, 30 min after: p = .008). In addition, increased parasympathetic activity by taVNS correlated with a greater increase in NWR threshold at Post 10 and Post 30 (Post 10: p = .003; Post 30: p = .001). The present results of this single-blinded study demonstrate the pain-suppressing effect of taVNS on NWR threshold and suggest that the degree of parasympathetic activation during taVNS may predict the pain-suppressing effect of taVNS after its application.
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Frecuencia Cardíaca , Sistema Nervioso Parasimpático , Reflejo , Estimulación del Nervio Vago , Humanos , Masculino , Femenino , Adulto , Estimulación del Nervio Vago/métodos , Reflejo/fisiología , Sistema Nervioso Parasimpático/fisiología , Adulto Joven , Frecuencia Cardíaca/fisiología , Estimulación Eléctrica Transcutánea del Nervio/métodos , Nocicepción/fisiologíaRESUMEN
BACKGROUND: Lumbar stabilization exercises (LSE) provide dynamic trunk stability, promote muscle strength and endurance, and improve low back pain rehabilitation and performance. OBJECTIVE: To clarify the differences in trunk muscle activity during LSEs on stable and different unstable surfaces. METHODS: Fifteen healthy males performed three exercises (elbow-toe, hand-knee, and side bridge) on stable (floor) and unstable surfaces. Muscle activity of the bilateral rectus abdominis, internal oblique, external oblique, and erector spinae were recorded. Data were compared using the Friedman test. Pairwise comparisons were performed using Wilcoxon's signed rank test if significant differences were observed. RESULTS: In the elbow-toe exercise, muscle activity of the rectus abdominis and right internal oblique increased in the following order: floor, low-difficulty, and high-difficulty unstable surface. In the hand-knee exercise, muscle activity of the internal oblique on the lower-extremity elevated side, external oblique, and erector spinae on the upper-extremity elevated side were greater on unstable surface exercise performance. In the side bridge exercise, rectus abdominis muscle activity was highest on a high-difficulty unstable surface. CONCLUSION: Trunk muscle activity increased during exercise on unstable surfaces. Since the effects of unstable surfaces vary depending on muscle and exercise types, exercise difficulty and surface stability must be considered accordingly.
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Terapia por Ejercicio , Humanos , Masculino , Terapia por Ejercicio/métodos , Adulto Joven , Adulto , Torso/fisiología , Región Lumbosacra/fisiología , Dolor de la Región Lumbar/rehabilitación , Dolor de la Región Lumbar/fisiopatología , Electromiografía , Recto del Abdomen/fisiología , Músculo Esquelético/fisiologíaRESUMEN
BACKGROUND: In baseball players with elbow injuries, towel drills are clinically used before initiating active throwing exercises to gradually increase stress across the elbow. However, elbow valgus torque during towel drills remains unknown. Moreover, towel drills and active ball throws might have different relationships between biomechanical metrics, such as elbow stress, arm slot, and arm speed. Therefore, the aims of this study were 1) to demonstrate the difference in elbow valgus stress between towel drills and active ball throws and 2) to evaluate the correlation between elbow valgus torque and other biomechanical metrics including arm slot and arm speed in towel drills and active ball throws. METHODS: Seventeen healthy college baseball players performed three towel drills using a face towel, short foam tube, and long foam tube, followed by full-effort throwing on flat ground. Each participant completed five consecutive trials of each task, and the elbow valgus torque, arm slot, and arm speed were measured using wearable sensors. One-way repeated analysis of variance and post-hoc tests were used to determine the differences in biomechanical metrics among the tasks. Furthermore, the correlation between the elbow valgus torque and other metrics was evaluated using Pearson correlation coefficients. RESULTS: Elbow valgus torque was lower in towel drills compared to that of active ball throws; however, the stress during towel drills using a face towel reached almost 80% of the maximum effort of active ball throws. There was no relationship between elbow valgus stress and arm slot in either the towel or active ball throw tasks. However, a higher arm speed was associated with greater elbow valgus torque in towel drills, whereas no relationship between elbow stress and arm speed was found in active ball throws. CONCLUSION: Precaution must be taken in athletes following a progressive throwing program because elbow valgus stress reaches almost 80% of the full-effort throw, even when using a face towel in a towel drill. Hence, the subjective intensity must be controlled even in towel drills to gradually increase the medial elbow stress. Moreover, the mechanisms underlying changes in elbow stress may differ between towel drills and active ball throws. Future investigations on the difference between towel drills and active ball throws may help understand the underlying mechanism of alterations in elbow valgus torque during the throwing movement.
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Traumatismos del Brazo , Béisbol , Articulación del Codo , Humanos , Brazo , Codo , Béisbol/lesiones , Fenómenos Biomecánicos , TorqueRESUMEN
This study aimed to evaluate the effects of the participant's attention target during repetitive passive movement (RPM) intervention on reciprocal inhibition (RI) and joint movement function. Twenty healthy adults participated in two experiments involving four attention conditions [control (forward attention with no RPM), forward attention (during RPM), monitor attention (monitor counting task during RPM), ankle joint attention (ankle movement counting task during RPM)] during 10-min RPM interventions on the ankle joint. Counting tasks were included to ensure the participant's attention remained on the target during the intervention. In Experiment 1, RI was measured before, immediately after, and 5, 10, 15, 20, and 30 min after the RPM intervention. In Experiment 2, we evaluated ankle joint movement function at the same time points before and after RPM intervention. The maximum ankle dorsiflexion movement (from 30° plantar flexion to 10° dorsiflexion) was measured, reflecting RI. In Experiment 1, the RI function reciprocal Ia inhibition was enhanced for 10 min after RPM under all attention conditions (excluding the control condition. D1 inhibition was enhanced for 20 min after RPM in the forward and monitor attention conditions and 30 min after RPM in the ankle joint attention condition. In Experiment 2, the joint movement function decreased under the forward and monitor attention conditions but improved under the ankle joint attention condition. This study is the first to demonstrate that the participant's attention target affected the intervention effect of the RI enhancement method, which has implications for improving the intervention effect of rehabilitation.
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Tobillo , Movimiento , Adulto , Humanos , Movimiento/fisiología , Articulación del Tobillo , Rango del Movimiento Articular/fisiología , Músculo EsqueléticoRESUMEN
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.
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Músculo Esquelético , Tendones , Humanos , Tobillo , Pie , CadáverRESUMEN
Background: Remote facilitation refers to teeth occlusion-activated spinal cord activity resulting in increased trunk and limb muscle strength. Facilitation depends on dentition-related pressure during occlusion and masticatory muscle contraction strength. Aims: This study aimed to clarify the neurophysiological phenomenon and mechanisms by which occlusal strength and balance affect leg muscle activity and smooth joint movement execution. Materials & Methods: To examine occlusal strength, three conditions were set: no contact between teeth and Moderate- and Maximum-strength occlusion (No-bite, Moderate, and Max conditions, respectively). To assess occlusal balance, we measured occlusal forces and calculated the left-right force ratio. We designated the sides with higher and lower occlusal pressure as hypertonic and hypotonic, respectively. We assessed ankle dorsiflexion movements with joint movement and isometric tasks. Results: The rate of joint development and peak ankle dorsiflexion torque were significantly higher under occlusion (moderate and max compared to No-bite conditions), and the joint movement performance time was significantly shorter under Moderate compared to No-bite conditions. The joint movement execution time change rate from No-bite to Moderate condition was significantly lower on the Hypertonic side. Joint movement function was most improved under Moderate conditions. Discussion: While remote facilitation improves with higher occlusal strength, leading to increased muscle strength, there is optimal occlusion intensity in joint movement. Moreover, an occlusal balance-dependent imbalance exists in remote facilitation between the Hyper- and Hypotonic sides. Conclusion: Thus, low-intensity occlusion is optimal for smooth joint movement, and unbalanced occlusion results in asymmetrical motor function facilitation.
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This study aimed to clarify the relationship between the joint and ligament structures of the subtalar joint and degeneration of the subtalar articular facet. We examined 50 feet from 25 Japanese cadavers. The number of articular facets, joint congruence, and intersecting angles were measured for the joint structure of the subtalar joint, and the footprint areas of the ligament attachments of the cervical ligament, interosseous talocalcaneal ligament (ITCL), and anterior capsular ligament were measured for the ligament structure. Additionally, subtalar joint facets were classified into Degeneration (+) and (-) groups according to degeneration of the talus and calcaneus. No significant relationship was identified between the joint structure of the subtalar joint and degeneration of the subtalar articular facet. In contrast, footprint area of the ITCL was significantly higher in the Degeneration (+) group than in the Degeneration (-) group for the subtalar joint facet. These results suggest that the joint structure of the subtalar joint may not affect degeneration of the subtalar articular facet. Degeneration of the subtalar articular facet may be related to the size of the ITCL.
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Inestabilidad de la Articulación , Articulación Talocalcánea , Humanos , Articulación del Tobillo , Ligamentos ArticularesRESUMEN
The aim of this study was to compare anterior knee laxity (AKL), genu recurvatum (GR), and muscle stiffness between reconstructed and contralateral sides in females who underwent anterior cruciate ligament (ACL) reconstruction during early follicular and ovulatory phases. AKL was measured as an anterior displacement of the tibia using a KS measure. GR was measured as the range of motion of knee hyperextension using a hyperextension apparatus. Muscle stiffness was measured for semitendinosus (ST) and biceps femoris long head (BF) using a MyotonPRO. The study investigated eighteen knees in nine females (Age, 20.4 ± 1.5 years; BMI, 21.5 ± 1.5) with normal menstrual cycles at least 1 year after reconstruction using hamstring autograft. E2 (Estradiol) concentration did not differ between the two phases, but AKL on the reconstructed side was lower during the ovulatory phase (8.3 [5.9-9.3] mm) than during the early follicular phase (9.4 [7.3-9.7] mm) (p = 0.044, r = 0.756), whereas there was no significant difference between the two phases on the contralateral side. AKL side-to-side difference, GR, and muscle stiffness (ST and BF) on both sides did not differ in either phase. These results indicate that AKL may behave differently on the reconstructed and contralateral sides during the menstrual cycle.
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Lesiones del Ligamento Cruzado Anterior , Reconstrucción del Ligamento Cruzado Anterior , Inestabilidad de la Articulación , Femenino , Humanos , Adolescente , Adulto Joven , Adulto , Articulación de la Rodilla/cirugía , Articulación de la Rodilla/fisiología , Extremidad Inferior/cirugía , Ciclo Menstrual/fisiología , Lesiones del Ligamento Cruzado Anterior/cirugíaRESUMEN
BACKGROUND: The purpose of this study was not only to examine the attachment site but also to quantify the effect of the tibialis posterior tendon (TPT) on each attachment site by examining the surface area of the attachment region. METHODS: We examined 100 feet from 50 Japanese cadavers. The TPT attachment to the navicular bone (NB), medial cuneiform bone (MCB), and lateral cuneiform bone (LCB) were set as the main attachment sites (Type I). The attachment seen in Type I with the addition of one additional site of attachment was defined as Type II. Furthermore, surface area was measured using a three-dimensional scanner. RESULTS: Attachment to the NB, MCB, and LCB was present in all specimens. The TPT attachment to the NB, MCB, and LCB comprised 75.1% of total attachment surface area. The ratio of the NB, MCB, and LCB in each type was about 90% in Types II and III, and 70-80% in Types IV-VII. CONCLUSION: The quantitative results demonstrated the NB, MCB, and LCB to be the main sites of TPT attachment, although individual differences in attachment sites exist, further developing the findings of previous studies.
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Procedimientos Ortopédicos , Huesos Tarsianos , Humanos , Tendones/cirugía , Pie , Huesos Tarsianos/cirugía , Tibia , CadáverRESUMEN
This study aimed to determine how transcutaneous vagus nerve stimulation (tVNS) alters autonomic nervous activity by comparing the effects of different tVNS frequencies and current intensities. We also investigated the sex-dependent autonomic response to tVNS. Thirty-five healthy adult participants were stimulated using a tVNS stimulator at the left cymba conchae while sitting on a reclining chair; tVNS-induced waveform changes were then recorded for different stimulus frequencies (Experiment 1: 3.0 mA at 100 Hz, 25 Hz, 10 Hz, 1 Hz, and 0 Hz (no stimulation)) and current intensities (Experiment 2: 100 Hz at 3.0 mA, 1.0 mA, 0.2 mA (below sensory threshold), and 0 mA (no stimulation)) using an electrocardiogram. Pulse widths were set at 250 µs in both experiment 1 and 2. Changes in heart rate (HR), root-mean-square of the difference between two successive R waves (RMSSD), and the ratio between low-frequency (LF) (0.04-0.15 Hz) and high-frequency (HF) (0.15-0.40 Hz) bands (LF/HF) in spectral analysis, which indicates sympathetic and parasympathetic activity, respectively, in heart rate variability (HRV), were recorded for analysis. Although stimulation at all frequencies significantly reduced HR (p = 0.001), stimulation at 100 Hz had the most pronounced effect (p = 0.001) in Experiment 1 and was revealed to be required to deliver at 3.0 mA in Experiment 2 (p = 0.003). Additionally, participants with higher baseline sympathetic activity experienced higher parasympathetic response during stimulation, and sex differences may exist in the autonomic responses by the application of tVNS. Therefore, our findings suggest that optimal autonomic changes induced by tVNS to the left cymba conchae vary depending on stimulating parameters and sex.
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This study aimed to clarify trunk muscle activity during jump header shooting and examine the immediate effects of trunk stabilization exercises on trunk muscle activity. Nineteen males who had played soccer for over 5 years were assigned to either the trunk stabilization exercise group or the control group. Muscle activity during jump header shooting was measured before and after intervention. The intervention in the trunk stabilization exercise group was trunk muscle training, whereas that in the control group was sitting. The phases of jump header shooting and the effects of the interventions were compared. In pre-intervention measurements, the internal oblique activity during the push-off phase and early floating phase was significantly greater than that during the late floating phase (p < 0.01667). In pre-intervention measurements, the muscle activity of the internal oblique increased from the push-off phase, prior to the increase in muscle activity of the rectus abdominis and external oblique, whereas the muscle activity of all abdominal muscles increased immediately after take-off. The trunk stabilization exercise intervention decreased the muscle activity of the erector spinae (p < 0.05). There seems to be a certain activation sequence in the abdominals during jump header shooting, and a single application of stabilization exercises could possibly reduce the activation of the back muscles.
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The purpose of this study was to investigate the changes in anterior knee laxity (AKL), stiffness, general joint laxity (GJL), and genu recurvatum (GR) during the menstrual cycle in female non-athletes and female athletes with normal and irregular menstrual cycles. Participants were 19 female non-athletes (eumenorrhea, n = 11; oligomenorrhea, n = 8) and 15 female athletes (eumenorrhea, n = 8; oligomenorrhea, n = 7). AKL was measured as the amount of anterior tibial displacement at 67 N-133 N. Stiffness was calculated as change in (Δ)force/Δ anterior displacement. The Beighton method was used to evaluate the GJL. The GR was measured as the maximum angle of passive knee joint extension. AKL, stiffness, GJL, and GR were measured twice in four phases during the menstrual cycle. Stiffness was significantly higher in oligomenorrhea groups than in eumenorrhea groups, although no significant differences between menstrual cycle phases were evident in female non-athletes. GR was significantly higher in the late follicular, ovulation, and luteal phases than in the early follicular phase, although no significant differences between groups were seen in female athletes. Estradiol may affect the stiffness of the periarticular muscles in the knee, suggesting that GR in female athletes may change during the menstrual cycle.
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The relationship between the morphological characteristics of the infrapatellar fat pad (IFP) and joint deformity has yet to be fully elucidated. Therefore, the purpose of this study was to clarify the morphological characteristics of the IFP and to identify the relationships between morphological characteristics of the IFP and degenerative grade of the articular surface of the patella. This investigation examined 41 legs from 25 Japanese cadavers. The IFP length, width, and volume were measured. It was categorized into three types: Type I, IFP proximal located on medial and lateral sides of the patella; Type II, the IFP proximal only located medially; and Type III, absence of the IFP proximal. Articular surfaces were graded as macroscopically intact or mildly altered (Grade I), moderately (Grade II), or severely (Grade III). Grade III was significantly more frequent than Grades I or II in Type III. IFP volume was significantly larger in Type I than in Types II or III. A negative correlation was found between the degenerative grade of the articular surface of the patella and IFP volume. It was suggested that a relationship between the degenerative grade of the articular surface of the patella and the IFP volume.
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Tejido Adiposo , Articulación de la Rodilla , Rótula , Tejido Adiposo/anatomía & histología , Cadáver , Humanos , Articulación de la Rodilla/anatomía & histología , Rótula/anatomía & histologíaRESUMEN
BACKGROUND: The relationship between contraction strength of the flexor-pronator muscles (FPMs) and elbow valgus braking function has not been clarified. HYPOTHESIS/PURPOSE: The purpose of this study was to investigate changes in medial elbow joint space when there is a difference in contraction strength of FPMs under elbow valgus stress. METHODS: Subjects were 20 healthy male university students, and the elbow joint on the nondominant hand side was used for measurements. The body position for limb measurement was sitting in a chair, with the shoulder abducted 60° and in 90° of external rotation, with 90° of elbow flexion. At first, maximum voluntary contraction (MVC) of the FPMs by grip motion was measured using a hand grip dynamometer under 60-N valgus stress. Contraction strengths of 10% MVC, 30% MVC, and 50% MVC were used. Ultrasonographic images of the medial elbow joint space (JS) were taken in the starting limb position. Using the Telos device system, load was then gradually increased by +10 N/s, and at the time of 60-N valgus stress, an image of the JS was taken. Furthermore, the subject adjusted to the set contraction strength (for about 5 sec) with 60-N valgus stress applied, and an image of the JS was taken while maintaining the set contraction strength. Each MVC condition (10% MVC, 30% MVC, and 50% MVC) was performed randomly. Three ultrasonographic images were taken within 10 seconds, and the average value of the three images was adopted as the JS. RESULTS: Compared with the JS under 60-N valgus stress, the JS was significantly reduced under 60-N valgus stress + 50% MVC. No significant difference was observed between the starting limb position and 60-N valgus stress + 50% MVC. CONCLUSION: FPMs may require muscle activity ≥50% MVC to brake 60-N elbow valgus stress.