RESUMEN
Numerous cross-sectional studies have attempted to identify the muscle morphology required to achieve high sprint velocity. Our longitudinal study addressed an unanswered question of cross-sectional studies: whether hypertrophy of the individual trunk and thigh muscles induced by daily training (e.g., sprint, jump, and resistance training) is linked to an improvement in sprint performance within well-trained sprinters. Twenty-three collegiate male sprinters (100-m best time of 11.36 ± 0.44 s) completed their daily training for 1 year without our intervention. Before and after the observation period, the sprint velocities at 0-100 m, 0-10 m, and 50-60 m intervals were measured using timing gates. The volumes of 14 trunk and thigh muscles were measured using magnetic resonance imaging. Muscle volumes were normalized to the participants' body mass at each time point. Sprint velocities increased at the 0-100 m (p < 0.001), 0-10 m (p = 0.019), and 50-60 m (p = 0.018) intervals after the observation period. The relative volumes of the tensor fasciae latae, sartorius, biceps femoris long head, biceps femoris short head, semitendinosus, and iliacus were increased (all p < 0.050). Among the hypertrophied muscles, only the change in the relative volume of the semitendinosus was positively correlated with the change in sprint velocity at the 50-60 m interval (p = 0.018 and ρ = 0.591). These findings suggest that semitendinosus hypertrophy seems to be associated with sprint performance improvement within well-trained sprinters during the maximal velocity phase.
Asunto(s)
Rendimiento Atlético , Imagen por Resonancia Magnética , Músculo Esquelético , Carrera , Muslo , Humanos , Masculino , Carrera/fisiología , Rendimiento Atlético/fisiología , Adulto Joven , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Músculo Esquelético/diagnóstico por imagen , Muslo/diagnóstico por imagen , Muslo/fisiología , Muslo/anatomía & histología , Estudios Longitudinales , Torso/fisiología , Entrenamiento de Fuerza/métodosRESUMEN
BACKGROUND: The Achilles tendon is one of the thickest, largest, and strongest tendons in the human body. Biomechanically, the AT represents the conjoint tendon of the triceps surae muscle, placed in series with the plantar fascia (PF) to ensure force transmission from the triceps surae toward the toes during walking, running, and jumping. Commonly encountered in the diagnostic evaluation of heel pain, Achilles tendinopathy (AT) refers to a combination of pathological changes affecting the tendon itself often resulting from excessive repetitive stress and overuse. Nevertheless, increasing evidence demonstrates that structural alterations due to overuse or abnormal patterns of skeletal muscle activity are not necessarily restricted to the muscles or tendons but can also affect the fascial tissue. At the same time, there has been recent discussion regarding the role of the fascial tissue as a potential contributor to the pathophysiological mechanisms of the development of several musculoskeletal disorders including tendinopathies. To the best of our knowledge, ultrasound (US) imaging studies on the fascial structures related to the triceps surae complex, as well as their possible correlation with Achillodynia have never been presented in the current literature. METHODS: In the present study, a comparative US imaging evaluation of textural features of the suro-Achilleo-plantar complex was performed in 14 healthy controls and 14 symptomatic subjects complaining of midportion AT. The thickness of the Achilles tendon, paratenon, intermuscular fascia, and PF has been assessed with US. In addition, both groups underwent the Victorian Institute of Sport Assessment-Achilles (VISA-A), a disease-specific questionnaire that measures the severity of symptoms of AT. Correlations between quantitative ultrasound measures and VISA-A scores were determined through Pearson or Spearman's rho correlations. RESULTS: Our ultrasonographic findings revealed statistically significant differences (p<0.05) in Achilles tendon and paratenon thicknesses between AT patients and controls. No significant differences were observed between groups in PF at the calcaneal insertion as all mean measures were within the expected range of a normal PF on US imaging. In contrast, in tendinopathic subjects, the deep intermuscular fascia between medial gastrocnemius (MG) and soleus (SOL) muscles is significantly (p<0.01) and considerably thickened compared to those of healthy subjects. Moderate correlations exist between tendon and paratenon thicknesses (r= 0.54, p= 0.04) and between MG-SOL fascia and tendon thicknesses (r= 0.58, p= 0.03). Regarding symptom severity and US morphological findings, the Spearman ρ test showed no correlation. CONCLUSIONS: Our data demonstrate that, in symptomatic subjects, US alterations are not restricted to paratenon and intratendinous areas, but also affect upstream structures along the myofascial chain, resulting in thickening of the fascia interposed between MG and SOL muscles. Moreover, positive correlations were found between MG-SOL fascia thickening and abnormalities in AT, paratenon, and symptom severity. Thus, US alterations in the fascial system should be interpreted within the clinical context of patients with AT as they may in turn represent important predictors of subsequent clinical outcomes and could help healthcare professionals and clinicians to refine non-operative treatment strategies and rehabilitation protocols for this disease.
Asunto(s)
Tendón Calcáneo , Fascia , Músculo Esquelético , Tendinopatía , Ultrasonografía , Humanos , Tendón Calcáneo/diagnóstico por imagen , Tendón Calcáneo/patología , Tendinopatía/diagnóstico por imagen , Tendinopatía/patología , Femenino , Estudios de Casos y Controles , Adulto , Fascia/diagnóstico por imagen , Fascia/patología , Fascia/anatomía & histología , Masculino , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/patología , Músculo Esquelético/anatomía & histología , Persona de Mediana EdadRESUMEN
The production of triceps surae plantarflexion moment is complex in that the Achilles tendon moment arm affects the Achilles tendon force by determining the muscle length change and shortening velocity during ankle rotation. In addition, there is evidence for associations between the sizes of muscles and their moment arm at the joints they span. These relationships between muscle architecture and tendon moment arm ultimately affect the muscle's force generating capacity and are thus important for understanding the roles played by muscles in producing locomotion. The purpose of this study was to investigate in vivo the relationship between architecture of two plantarflexors and the Achilles tendon moment arm in a healthy adult population. Ultrasound-based measurements were made of the architecture (fascicle length, muscle volume, physiological cross-sectional area, and anatomical cross-sectional area) of the lateral and medial gastrocnemius and the Achilles tendon moment arm was assessed using a technique that combined ultrasound imaging and motion analysis. Positive correlations were observed between the length (r = 0.499, p = 0.049) and size variables (muscle volume r = 0.621, p = 0.010; ACSA r = 0.536, p = 0.032) of the lateral gastrocnemius and the Achilles tendon moment arm, but correlations were only observed for size variables (muscle volume r = 0.638, p = 0.008; PCSA r = 0.525, p = 0.037; ACSA r = 0.544, p = 0.029), and not the length, of the medial gastrocnemius. These findings suggest lateral gastrocnemius adapts to moment arms to maintain force production throughout the range of motion across individuals, while the medial gastrocnemius does not and is thus better suited for static force generation.
Asunto(s)
Tendón Calcáneo , Músculo Esquelético , Ultrasonografía , Humanos , Tendón Calcáneo/fisiología , Tendón Calcáneo/diagnóstico por imagen , Tendón Calcáneo/anatomía & histología , Músculo Esquelético/fisiología , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/anatomía & histología , Adulto , Masculino , Femenino , Fenómenos Biomecánicos , Rango del Movimiento Articular/fisiología , Adulto Joven , Articulación del Tobillo/fisiología , Articulación del Tobillo/diagnóstico por imagen , Articulación del Tobillo/anatomía & histologíaRESUMEN
Take-off is a vital part of powered flight which likely constrains the size of birds, yet extinct pterosaurs are known to have reached far larger sizes. Three different hypothesised take-off motions (bipedal burst launching, bipedal countermotion launching, and quadrupedal launching) have been proposed as explanations for how pterosaurs became airborne and circumvented this proposed morphological limit. We have constructed a computational musculoskeletal model of a 5 m wingspan ornithocheiraean pterosaur, reconstructing thirty-four key muscles to estimate the muscle moment arms throughout the three hypothesised take-off motions. Range of motion constrained hypothetical kinematic sequences for bipedal and quadrupedal take-off motions were modelled after extant flying vertebrates. Across our simulations we did not find higher hindlimb moment arms for bipedal take-off motions or noticeably higher forelimb moment arms in the forelimb for quadrupedal take-off motions. Despite this, in all our models we found the muscles utilised in the quadrupedal take-off have the largest total launch applicable moment arms throughout the entire take-off sequences and for the take-off pose. This indicates the potential availability of higher leverage for a quadrupedal take-off than hypothesised bipedal motions in pterosaurs pending further examination of muscle forces.
Asunto(s)
Dinosaurios , Vuelo Animal , Animales , Fenómenos Biomecánicos , Vuelo Animal/fisiología , Dinosaurios/fisiología , Dinosaurios/anatomía & histología , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Fósiles , Modelos Biológicos , Miembro Anterior/fisiología , Miembro Anterior/anatomía & histología , Simulación por ComputadorRESUMEN
PURPOSE: The saphenous nerve is a predominantly sensory nerve. It is the longest nerve of the body which supplies the skin of the medial side of the leg and foot as far as the ball of the great toe. We present here an unusual motor branch of the saphenous nerve to the sartorius muscle. METHOD: Institutional guidelines for use of human cadaver were followed. Routine dissection of the lower limbs for undergraduate medical teaching was performed in a 67 years old female cadaver employing standard methods. Relevant gross features of the variations were photographed. H&E staining of relevant structure was done and photomicrographed. RESULTS: The unusual motor branch to Sartorius was observed in the right thigh. The branch was given off in the lower third of the thigh after the saphenous nerve exited the adductor canal. The branch was distinctly seen entering the substance of the sartorius. The structure was confirmed to be a peripheral nerve by histological examination. The saphenous nerve then descended between the sartorius and gracilis tendons, pierced the fascia lata and became cutaneous. CONCLUSION: The motor branch to the sartorius muscle is a very rare branch whose knowledge is important for clinicians as it can get damaged during arthroscopy and other knee surgery or during adductor canal block.
Asunto(s)
Variación Anatómica , Cadáver , Músculo Esquelético , Humanos , Femenino , Anciano , Músculo Esquelético/inervación , Músculo Esquelético/anatomía & histología , Disección , Muslo/inervación , Nervio Femoral/anatomía & histologíaRESUMEN
PURPOSE: The brachioradialis muscle (BRM) belongs to the lateral group of forearm muscles and contributes to the elbow flexion. Accessory brachioradialis muscle (ABRM) or "brachioradialis accessorius" represents an uncommon BRM variant, not been enough studied. The present study investigates the prevalence of the ABRM, along with its origin, insertion, and innervation. MATERIALS: Eighty-three upper limbs were meticulously dissected at the arm, forearm, and cubital fossa to investigate the ABRM presence. When the variant muscle was identified, morphometric measurements were obtained. RESULTS: The ABRM was identified in two upper limbs (2/83, 2.4%), in a male cadaver, bilaterally. Its origin was located along with the typical BRM, and its insertion was identified into the anterior surface of the radius (proximal third). The ABRM was innervated by the radial nerve, coursing posteriorly (deeply). CONCLUSIONS: In the current study, the variant muscle was observed in 2.4%. Radial nerve compression, at the forearm, is not an uncommon entrapment neuropathy. The relationship between the radial nerve and the ABRM could precipitate radial neuropathy.
Asunto(s)
Variación Anatómica , Cadáver , Antebrazo , Músculo Esquelético , Humanos , Masculino , Músculo Esquelético/anomalías , Músculo Esquelético/anatomía & histología , Músculo Esquelético/inervación , Prevalencia , Antebrazo/inervación , Antebrazo/anomalías , Antebrazo/anatomía & histología , Femenino , Nervio Radial/anatomía & histología , Nervio Radial/anomalías , Anciano , Persona de Mediana Edad , Síndromes de Compresión Nerviosa/diagnóstico , Disección , Anciano de 80 o más AñosRESUMEN
Minimalist walking shoes have been shown to improve foot muscle size and strength in active adults, but not in our previous study involving children, which could relate to the more structured footwear used in our study. Hence, this study examined the effects of true minimalists on intrinsic foot muscle size and strength, foot arch integrity, and physical function among primary school children. After a baseline assessment, 30 primary school students aged between 9 and 12 were given a pair of minimalist shoes (minimalist index = 92%) as their regular school shoes for two school terms, followed by a re-assessment. Seventeen of the 30 participants in the minimalist group completed the study. Compared to the control group, the minimalist group showed significantly increased cross-sectional area of abductor hallucis (p = 0.047, Cohen's d = 0.57) and flexor digitorum brevis (p = 0.037, Cohen's d = 0.80), increased strength of the hallux (p = 0.015, Cohen's d = 0.76) and lesser toes (p = 0.014, Cohen's d = 0.66), greater arch height (p = 0.020, Cohen's d = 0.52) and standing long jump distance (p = 0.001, Cohen's d = 9.79). The control group exhibited improved standing long jump performance only (p = 0.020, Cohen's d = 10.70). Minimalist shoes worn daily to school promote intrinsic foot muscle size and strength, and improve foot arch integrity among primary school students.
Asunto(s)
Pie , Fuerza Muscular , Músculo Esquelético , Zapatos , Humanos , Niño , Fuerza Muscular/fisiología , Pie/fisiología , Pie/anatomía & histología , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Masculino , Femenino , Caminata/fisiología , Diseño de Equipo , Instituciones AcadémicasRESUMEN
PURPOSE: Sarcopenic obesity is a combination of sarcopenia and obesity, which is associated with the onset of disability. Fat to muscle ratio (FMR) is a screening measure that assesses the ratio of muscle mass to fat mass. However, the relationship between the FMR and disability has not been investigated. METHODS: This study included 11,427 community-dwelling older adults aged ≥65 years enrolled in NCGG-SGS (National Center for Geriatrics and Gerontology-Study of Geriatric Syndromes), a national cohort study in Japan. FMR was measured by the bioelectrical impedance analysis and calculated by dividing fat mass by muscle mass. Cox proportional hazard regression analysis adjusted for covariates was used to investigate the association between FMR and the risk of developing new care needs at 5 years. FMR was divided by about quintile, with quintile 5 as the high. RESULTS: The high FMR group had the highest incidence of disability at 20.8 % for women and 20.1 % for men. In women, the association between FMR and disability was significantly different for the FMR (hazard risk [HR]: 1.43, 95 % confidence interval [CI]: 1.16-1.75). There was no association between FMR and disability in men (HR: 0.98, 95 %CI: 0.76-1.25). Lagged analyses accounting for reverse causality did not change the relationship. CONCLUSIONS: FMR is associated with increased risk of disability in women community-dwelling older adults but not among men. Because the rate of decreased muscle strength is faster in men than in women, early decreased muscle strength may affect men's risk of disability more than muscle mass or fat mass.
Asunto(s)
Vida Independiente , Sarcopenia , Humanos , Masculino , Femenino , Anciano , Japón/epidemiología , Estudios Longitudinales , Sarcopenia/epidemiología , Sarcopenia/fisiopatología , Músculo Esquelético/anatomía & histología , Obesidad/epidemiología , Evaluación Geriátrica/métodos , Personas con Discapacidad/estadística & datos numéricos , Tejido Adiposo/anatomía & histología , Composición Corporal/fisiología , Anciano de 80 o más Años , Factores de Riesgo , Modelos de Riesgos Proporcionales , Impedancia Eléctrica , Evaluación de la Discapacidad , Pueblos del Este de AsiaRESUMEN
PURPOSE: Depending on its axis, pronation varies from the radius rotation around the steady ulna to the reciprocal adduction of the radius and abduction of the ulna. While there is no question that pronator teres is a central pronation agonist, anconeus's role is not settled. The current investigation comparing palpation and ultrasonography in these two muscles during pronation along the axis capitulum-second digit evolved from a serendipitous finding in a clinical anatomy seminar. METHODS: Single-hand palpation and two-transducer ultrasonography over anconeus and pronator teres were used on ten normal subjects to investigate their contraction during pronation around the capitulum-second digit axis. These studies were done independently and blind to the results of the other. The statistical analysis between palpation and ultrasonography was performed with Cohen's kappa coefficient and the χ2 test. RESULTS: On palpation, on resisted full pronation, anconeus contracted in 8/10 subjects and pronator teres in 10/10 subjects. Without resistance, the corresponding ratios were 5/10 and 9/10. On two-transducer ultrasonography, the comparable ratios were 7/10 and 10/10, and 3/10 and 10/10. A fair concordance (Cohen's kappa = 0.21) between palpation and ultrasonography in detecting the simultaneous status of anconeus and pronator teres during resisted full pronation. Anatomic dissection illustrated the elements involved. CONCLUSIONS: Plain palpation confirmed by ultrasonography showed the simultaneous contraction of anconeus and pronator teres during resisted pronation in most of the studied subjects. The study suggests that palpation can be helpful in directly studying muscle activity during movement.
Asunto(s)
Voluntarios Sanos , Músculo Esquelético , Palpación , Pronación , Ultrasonografía , Humanos , Pronación/fisiología , Ultrasonografía/métodos , Masculino , Adulto , Femenino , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Palpación/métodos , Adulto Joven , Contracción Muscular/fisiologíaRESUMEN
Skeletal muscle architecture is a strong predictor of in vivo functional capacity and is evaluated in fixed tissues, accommodating the study of human muscles from cadaveric donors. Previous studies evaluating the pelvic floor muscles (PFMs) demonstrated that the rat is the most appropriate small animal model for the study of female PFM architecture, but the rat's suitability for the study of male PFMs is undetermined. We aimed to determine (1) whether PFM architecture exhibits sexual dimorphism in rats or humans, and (2) if the rat is also a suitable animal model for the study of male human PFMs. PFMs were fixed in situ and harvested en bloc from male and female cadaveric donors and 3-month-old male and female Sprague-Dawley rats. Three architectural parameters influenced by species size were used to compare male versus female PFMs within species, while four size-independent measures compared species within sex. All comparisons were made with two-way analysis of variances and Tukey's multiple comparisons tests post hoc. Sarcomere length (rats and humans, p = 0.016 and = 0.002) and normalized fiber length (rats, p < 0.001) were significantly larger in male PFMs. Three of the size-independent measures exhibited similar species trends in both sexes, while the size-independent sarcomere length measure (Ls/Lso) differed between male rats and humans (p < 0.001). Thus, sexual dimorphism is present in rat and human PFM architecture, and the male rat is suitable for studies of human male PFMs.
Asunto(s)
Diafragma Pélvico , Ratas Sprague-Dawley , Caracteres Sexuales , Animales , Diafragma Pélvico/anatomía & histología , Diafragma Pélvico/fisiología , Femenino , Masculino , Humanos , Ratas , Músculo Esquelético/anatomía & histología , Músculo Esquelético/fisiologíaRESUMEN
PURPOSE: A deep knowledge of the variations of the posterior forearm musculature is crucial for assessing and diagnosing conditions in this region. Extensor indicis (EI) is one of the muscles in this region, which exhibits diverse anatomical variations. This report documents an extremely unusual form of the EI with an accessory head on the dorsum of the hand. METHODS: During routine dissection, an extremely rare presentation of the EI was found in the left forearm of a 94-year-old female cadaver. RESULTS: This unusual EI consisted of two muscle bellies. The traditional belly originated from the distal two-thirds of the ulna. The muscle became tendinous around the carpal area, distal to the extensor retinaculum. The tendon was subsequently joined by an accessory muscle belly originating from the distal radioulnar ligament. The EI tendon inserted onto the dorsal expansion of the index finger, ulnar to that of the extensor digitorum. The posterior interosseous nerve innervated the muscle. CONCLUSION: Herein, we report an extremely rare form of the EI. To our knowledge, EI with an accessory head has only been reported rarely over the past 200 years. Moreover, our report appears to be the first case with photographic details of this anatomical variation. Clinicians should be aware of this variation for proper diagnosis and treatment.
Asunto(s)
Variación Anatómica , Cadáver , Antebrazo , Músculo Esquelético , Humanos , Femenino , Anciano de 80 o más Años , Músculo Esquelético/anomalías , Músculo Esquelético/anatomía & histología , Antebrazo/anomalías , Antebrazo/inervación , Tendones/anomalías , Tendones/anatomía & histología , DisecciónRESUMEN
Objective: To investigate the effects of 12-week weight-bearing dance aerobics (WBDA) on muscle morphology, strength and functional fitness in older women. Methods: This controlled study recruited 37 female participants (66.31y ± 3.83) and divided them into intervention and control groups according to willingness. The intervention group received 90-min WBDA thrice a week for 12 weeks, while the control group maintained normal activities. The groups were then compared by measuring muscle thickness, fiber length and pennation angle by ultrasound, muscle strength using an isokinetic multi-joint module and functional fitness, such as 2-min step test, 30-s chair stand, chair sit-and-reach, TUG and single-legged closed-eyed standing test. The morphology, strength, and functional fitness were compared using ANCOVA or Mann-Whitney U test to study the effects of 12 weeks WBDA. Results: Among all recruited participants, 33 completed all tests. After 12 weeks, the thickness of the vastus intermedius (F = 17.85, P < 0.01) and quadriceps (F = 15.62, P < 0.01) was significantly increased in the intervention group compared to the control group, along with a significant increase in the torque/weight of the knee flexor muscles (F = 4.47, P = 0.04). Similarly, the intervention group revealed a significant improvement in the single-legged closed-eyed standing test (z = -2.16, P = 0.03) compared to the control group. Conclusion: The study concluded that compared to the non-exercising control group, 12-week WBDA was shown to thicken vastus intermedius, increase muscle strength, and improve physical function in older women. In addition, this study provides a reference exercise program for older women.
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Baile , Fuerza Muscular , Soporte de Peso , Humanos , Femenino , Fuerza Muscular/fisiología , Anciano , Baile/fisiología , Soporte de Peso/fisiología , Aptitud Física/fisiología , Extremidad Inferior/fisiología , Extremidad Inferior/diagnóstico por imagen , Persona de Mediana Edad , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Músculo Esquelético/diagnóstico por imagen , Ejercicio Físico/fisiología , Músculo Cuádriceps/fisiología , Músculo Cuádriceps/diagnóstico por imagen , Músculo Cuádriceps/anatomía & histologíaRESUMEN
ABSTRACT: Moeskops, S, Oliver, JL, Radnor, JM, Haff, GG, Myer, GD, Ramachandran, AK, Kember, LS, Pedley, JS, and Lloyd, RS. Effects of neuromuscular training on muscle architecture, isometric force production, and stretch-shortening cycle function in trained young female gymnasts. J Strength Cond Res 38(9): 1640-1650, 2024-This study evaluated the effects of a 10-month neuromuscular training (NMT) intervention on muscle architecture, isometric force production, and stretch-shortening cycle (SSC) function. Thirty-seven girls aged 6-12 years were placed into gymnastics + NMT (gNMT; n = 15), gymnastics only (GYM; n = 10), or maturity-matched control (CON; n = 12) groups. The gNMT group followed a 10-month NMT program in addition to gymnastics training, whereas the GYM group only participated in gymnastics training. Isometric midthigh pull (IMTP) and drop jump (DJ) kinetics were measured, in addition to muscle thickness, fascicle length, and pennation angle of the gastrocnemius medialis at baseline and at 4, 7, and 10 months. A 3 × 4 (group × time) repeated-measures ANCOVA (covariate, % predicted adult height) was used to evaluate within-group changes. Significance level was set at p < 0.05. Significant interaction effects were observed in muscle thickness, absolute (PF abs ) and relative peak force (PF rel ) in the IMTP and various DJ variables. The gNMT group demonstrated improvements in muscle thickness, IMTP PF abs and PF rel , and DJ kinetics, most commonly evidenced from 7 months onward. The GYM group's muscle thickness also significantly improved, accompanied by improvements in some DJ kinetics. The CON group did not experience any desirable changes. Overall, NMT elicited positive changes in muscle thickness, PF abs and PF rel , and SSC function to a greater extent than gymnastics training alone or growth and maturation. As most adaptations took 7 months, longer-term NMT programs should be implemented with youth female gymnasts.
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Gimnasia , Contracción Isométrica , Músculo Esquelético , Humanos , Gimnasia/fisiología , Femenino , Niño , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Contracción Isométrica/fisiología , Fuerza Muscular/fisiología , Acondicionamiento Físico Humano/métodos , Acondicionamiento Físico Humano/fisiologíaRESUMEN
Computational models of musculoskeletal systems are essential tools for understanding how muscles, tendons, bones, and actuation signals generate motion. In particular, the OpenSim family of models has facilitated a wide range of studies on diverse human motions, clinical studies of gait, and even non-human locomotion. However, biological structures with many joints, such as fingers, necks, tails, and spines, have been a longstanding challenge to the OpenSim modeling community, especially because these structures comprise numerous bones and are frequently actuated by extrinsic muscles that span multiple joints-often more than three-and act through a complex network of branching tendons. Existing model building software, typically optimized for limb structures, makes it difficult to build OpenSim models that accurately reflect these intricacies. Here, we introduce ArborSim, customized software that efficiently creates musculoskeletal models of highly jointed structures and can build branched muscle-tendon architectures. We used ArborSim to construct toy models of articulated structures to determine which morphological features make a structure most sensitive to branching. By comparing the joint kinematics of models constructed with branched and parallel muscle-tendon units, we found that among various parameters-the number of tendon branches, the number of joints between branches, and the ratio of muscle fiber length to muscle tendon unit length-the number of tendon branches and the number of joints between branches are most sensitive to branching modeling method. Notably, the differences between these models showed no predictable pattern with increased complexity. As the proportion of muscle increased, the kinematic differences between branched and parallel models units also increased. Our findings suggest that stress and strain interactions between distal tendon branches and proximal tendon and muscle greatly affect the overall kinematics of a musculoskeletal system. By incorporating complex muscle-tendon branching into OpenSim models using ArborSim, we can gain deeper insight into the interactions between the axial and appendicular skeleton, model the evolution and function of diverse animal tails, and understand the mechanics of more complex motions and tasks.
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Articulaciones , Músculo Esquelético , Programas Informáticos , Tendones , Tendones/fisiología , Tendones/anatomía & histología , Humanos , Fenómenos Biomecánicos , Articulaciones/fisiología , Articulaciones/anatomía & histología , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Modelos Biológicos , Biología Computacional , Simulación por Computador , AnimalesRESUMEN
This study investigates gender differences in core muscle morphology among elite alpine skiers using ultrasonography, highlighting significant disparities that could influence training and injury prevention strategies. METHODS: A cross-sectional design was employed, examining ultrasound imaging (USI) in 22 elite skiers (11 male, 11 female) to assess the thickness of the external oblique (EO), internal oblique (IO), transversus abdominis (TrAb), and rectus abdominis (RA) muscles. RESULTS: Significant differences were noted, with male skiers displaying greater muscle thickness, particularly in the right IO and RA and left IO, EO, TrAb, and RA. CONCLUSIONS: These findings suggest that male and female skiers may require different training approaches to optimize performance and reduce injury risks. This research contributes to a deeper understanding of the physical demands on elite skiers and underscores the need for gender-specific training regimens to enhance athletic outcomes and prevent injuries.
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Esquí , Ultrasonografía , Humanos , Esquí/fisiología , Femenino , Masculino , Ultrasonografía/métodos , Estudios Transversales , Adulto , Adulto Joven , Factores Sexuales , Músculo Esquelético/fisiología , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/anatomía & histología , Atletas , Músculos Abdominales/diagnóstico por imagen , Músculos Abdominales/fisiología , Músculos Abdominales/anatomía & histologíaRESUMEN
Birds, bats and insects have evolved unique wing structures to achieve a wide range of flight capabilities. Insects have relatively stiff and passive wings, birds have a complex and hierarchical feathered structure and bats have an articulated skeletal system integrated with a highly stretchable skin. The compliant skin of the wing distinguishes bats from all other flying animals and contributes to bats' remarkable, highly manoeuvrable flight performance and high energetic efficiency. The structural and functional complexity of the bat wing skin is one of the least understood although important elements of the bat flight anatomy. The wing skin has two unusual features: a discrete array of very soft elastin fibres and a discrete array of skeletal muscle fibres. The latter is intriguing because skeletal muscle is typically attached to bone, so the arrangement of intramembranous muscle in soft skin raises questions about its role in flight. In this paper, we develop a multi-scale chemo-mechanical constitutive model for bat wing skin. The chemo-mechanical model links cross-bridge cycling to a structure-based continuum model that describes the active viscoelastic behaviour of the soft anisotropic skin tissue. Continuum models at the tissue length-scale are valuable as they are easily implemented in commercial finite element codes to solve problems involving complex geometries, loading and boundary conditions. The constitutive model presented in this paper will be used in detailed finite element simulations to improve our understanding of the mechanics of bat flight in the context of wing kinematics and aerodynamic performance.
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Quirópteros , Vuelo Animal , Modelos Biológicos , Músculo Esquelético , Alas de Animales , Animales , Quirópteros/fisiología , Quirópteros/anatomía & histología , Alas de Animales/fisiología , Alas de Animales/anatomía & histología , Vuelo Animal/fisiología , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Fenómenos Biomecánicos , Fenómenos Fisiológicos de la PielRESUMEN
INTRODUCTION: Increases in skeletal muscle size occur in response to prolonged exposure to resistance training that is typically ascribed to increased muscle fiber size. Whether muscle fiber number also changes remains controversial, and a paucity of data exists about myofibrillar structure. This cross-sectional study compared muscle fiber and myofibril characteristics in long-term resistance-trained (LRT) versus untrained (UNT) individuals. METHODS: The maximal anatomical cross-sectional area (ACSAmax) of the biceps brachii muscle was measured by magnetic resonance imaging in 16 LRT (5.9 ± 3.5 yr' experience) and 13 UNT males. A muscle biopsy was taken from the biceps brachii to measure muscle fiber area, myofibril area, and myosin spacing. Muscle fiber number, and myofibril number in total and per fiber were estimated by dividing ACSAmax by muscle fiber area or myofibril area, and muscle fiber area by myofibril area, respectively. RESULTS: Compared with UNT, LRT individuals had greater ACSAmax (+70%, P < 0.001), fiber area (+29%, P = 0.028), fiber number (+34%, P = 0.013), and myofibril number per fiber (+49%, P = 0.034) and in total (+105%, P < 0.001). LRT individuals also had smaller myosin spacing (-7%, P = 0.004; i.e., greater packing density) and a tendency toward smaller myofibril area (-16%, P = 0.074). ACSAmax was positively correlated with fiber area ( r = 0.526), fiber number ( r = 0.445), and myofibril number (in total r = 0.873 and per fiber r = 0.566), and negatively correlated with myofibril area ( r = -0.456) and myosin spacing ( r = -0.382) (all P < 0.05). CONCLUSIONS: The larger muscles of LRT individuals exhibited more fibers in cross-section and larger muscle fibers, which contained substantially more total myofibrils and more packed myofilaments than UNT participants, suggesting plasticity of muscle ultrastructure.
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Fibras Musculares Esqueléticas , Miofibrillas , Entrenamiento de Fuerza , Humanos , Miofibrillas/fisiología , Masculino , Entrenamiento de Fuerza/métodos , Estudios Transversales , Fibras Musculares Esqueléticas/fisiología , Adulto , Imagen por Resonancia Magnética , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Adulto Joven , Miosinas/metabolismoRESUMEN
OBJECTIVES: The aim of this study was to compare torque-velocity profiles, muscle architecture, tendon dimensions, and bilateral-symmetry between competitive cyclists (CY), competitive runners (RN), ice-hockey players (IH), basketball players (BP), and physically-active individuals (CN) (n=10 for each group). METHODS: Vastus lateralis (VL) muscle and patellar tendon (PT) structures were determined with B-mode ultrasonography, and maximal knee extensor isokinetic torque was assessed at three different velocities. RESULTS: Optimal torque and velocity were lower in runners than CY, BP and IH (p<0.05). Maximal power was similar between the athlete groups but greater than CN (p<0.05). Furthermore, RN and BP reached their peak-torque at longer muscle lengths compared to IH and CY (p<0.05). RN had the lowest VL muscle thickness and the greatest fascicle length, while CY had the greatest pennation angle (p<0.05). CY had the greatest PT thickness, particularly at the proximal and medial sites, while BP at the distal point (p<0.05), with similar trends observed for PT cross-sectional-area. CONCLUSIONS: Our findings show that even if power generating capacity is similar between athletic disciplines, there are discipline-specific muscle adaptations, where particularly runners appear to have muscles adapted for speed rather than torque development, while in cyclists, velocity is sacrificed for torque development.
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Atletas , Torque , Humanos , Masculino , Adulto , Adulto Joven , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Músculo Esquelético/diagnóstico por imagen , Ultrasonografía/métodos , Ligamento Rotuliano/fisiología , Ligamento Rotuliano/diagnóstico por imagen , Ligamento Rotuliano/anatomía & histología , Carrera/fisiologíaRESUMEN
Introduction: The interest in estimating muscle mass (MM) and bone mass (BM) has grown in the sporting arena, and more specifically in recreational strength trainees, leading to the creation of different strategies to assess them. The aims were: 1) to investigate the agreement between different MM and BM formulas, and the muscle-bone index (MBI), and to establish the differences between them, in a healthy young adult population; and 2) to analyze if there are differences between males and females in the comparison of MM, BM and MBI formulas. Methods: This study followed a descriptive cross-sectional design. A total of 130 adult active recreational strength trainees were evaluated according to the procedures described by the International Society for the Advancement in Kinanthropometry (ISAK). Estimations were made in kilograms of MM and BM by following the equations by different authors. Results: The results showed significant differences between the values obtained by all the MM and BM formulas in the general sample (p < 0.001), and by the majority of formulas for male and female samples. In the general sample, Lin's coefficient indicated a strong agreement between Kerr, Lee, and Poortmans' MM estimation equations (concordance correlation coefficient (CCC) = 0.96-0.97). However, when stratifying by sex, this agreement persisted only in males (CCC = 0.90-0.94), in contrast with a lack of agreement observed in females (CCC < 0.90). Discrepancies in bone mass agreement were noted both in the general sample (CCC < 0.15) and when stratified by sex (CCC < 0.12). Conclusions: In general, differences were found between the values reported by the MM and BM formulas in recreational strength trainees, without an agreement between them. Sex was shown to significantly influence the differences found. The practical implications are that when comparing an individual with reference tables, other studies, or if analyzing an individual's evolution, the same estimation equation should be used, as they are not interchangeable.
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Antropometría , Músculo Esquelético , Humanos , Masculino , Femenino , Estudios Transversales , Adulto , Antropometría/métodos , Adulto Joven , Músculo Esquelético/fisiología , Músculo Esquelético/anatomía & histología , Densidad Ósea/fisiología , Fuerza Muscular/fisiología , Composición Corporal/fisiología , Factores SexualesRESUMEN
Accurate detection of the levator scapulae muscle is critical for effective diagnostic and therapeutic interventions. The commonly used surface anatomy approach has not been validated and is less accurate than ultrasound-guided techniques. Therefore, we determined the needle insertion point for the levator scapulae using a new technique based on the anatomy of the scapula. This investigation used 15 fresh-frozen cadavers to explore the relationship between the acromial angle and medial tip of the scapular spine (O) of the scapular spine. Based on the x-axis (the distance [L] from Point O to point acromial angle) and the y-axis perpendicular to the x-axis passing through Point O, the barycentric coordinates were determined through the intersections of each axis and the superior angle of the scapula with the levator scapulae. Various ratios involving the established distance L) were ascertained, we compared the measurements and ratios between the male and female groups, and the accuracy of the new technique was compared with the conventional technique. The optimal site of the new technique was within 6 to 7% of distance L on the x-axis and 42 to 44% of distance L on the y-axis. This technique was significantly more accurate than the conventional technique (Pâ =â .006). Although ultrasound allows for accurate injections via real-time visualization, its unavailability in some cases highlights the importance of understanding surface anatomy landmarks. Our new technique, based on the anatomy of the scapula and relative measurements, is more accurate than the conventional technique. This should enable more precise detection of the levator scapulae for accurate and efficient diagnostic and therapeutic procedures.