RESUMO
BACKGROUND: Lack of initial in-brace correction is strongly predictive for brace treatment failure in adolescent idiopathic scoliosis (AIS) patients. Computer-aided design (CAD) technology could be useful in quantifying the trunk in 3D and brace characteristics in order to further investigate the effect of brace modifications on initial in-brace correction and subsequently long-term brace treatment success. The purpose of this pilot study was to identify parameters obtained from 3D surface scans which influence the initial in-brace correction (IBC) in a Boston brace in patients with AIS. METHODS: Twenty-five AIS patients receiving a CAD-based Boston brace were included in this pilot study consisting of 11 patients with Lenke classification type 1 and 14 with type 5 curves. The degree of torso asymmetry and segmental peak positive and negative torso displacements were analyzed with the use of patients' 3D surface scans and brace models for potential correlations with IBC. RESULTS: The mean IBC of the major curve on AP view was 15.9% (SD = 9.1%) for the Lenke type 1 curves, and 20.1% (SD = 13.9%) for the type 5 curves. The degree of torso asymmetry was weakly correlated with patient's pre-brace major curve Cobb angle and negligible correlated with major curve IBC. Mostly weak or negligible correlations were observed between IBC and the twelve segmental peak displacements for both Lenke type 1 and 5 curves. CONCLUSION: Based on the results of this pilot study, the degree of torso asymmetry and segmental peak torso displacements in the brace model alone are not clearly associated with IBC.
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Cifose , Escoliose , Humanos , Adolescente , Projetos Piloto , Escoliose/diagnóstico por imagem , Escoliose/terapia , Braquetes , Computadores , Tronco/diagnóstico por imagemRESUMO
Adolescent Idiopathic Scoliosis (AIS) is a 3D spine deformity that also causes ribcage and torso distortion. While clinical metrics are important for monitoring disorder progression, patients are often most concerned about their cosmesis. The aim of this study was to automate the quantification of AIS cosmesis metrics, which can be measured reliably from patient-specific 3D surface scans (3DSS). An existing database of 3DSS for pre-operative AIS patients treated at the Queensland Children's Hospital was used to create 30 calibrated 3D virtual models. A modular generative design algorithm was developed on the Rhino-Grasshopper software to measure five key AIS cosmesis metrics from these models-shoulder, scapula and hip asymmetry, torso rotation and head-pelvis shift. Repeat cosmetic measurements were calculated from user-selected input on the Grasshopper graphical interface. InterClass-correlation (ICC) was used to determine intra- and inter-user reliability. Torso rotation and head-pelvis shift measurements showed excellent reliability (> 0.9), shoulder asymmetry measurements showed good to excellent reliability (> 0.7) and scapula and hip asymmetry measurements showed good to moderate reliability (> 0.5). The ICC results indicated that experience with AIS was not required to reliably measure shoulder asymmetry, torso rotation and head-pelvis shift, but was necessary for the other metrics. This new semi-automated workflow reliably characterises external torso deformity, reduces the dependence on manual anatomical landmarking, and does not require bulky/expensive equipment.
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Cosméticos , Cifose , Escoliose , Criança , Humanos , Adolescente , Escoliose/cirurgia , Reprodutibilidade dos Testes , Tronco , OmbroRESUMO
BACKGROUND: Work-related low-back disorders (WLBDs) are one of the most frequent and costly musculoskeletal conditions. It has been showed that WLBDs may occur when intervertebral or torso equilibrium is altered by a biomechanical perturbations or neuromuscular control error. The capacity to react to such disturbances is heavily determined by the spinal stability, provided by active and passive tissues and controlled by the central nervous system. RESEARCH QUESTION: This study aims to investigate trunk stability through the Lyapunov's maximum exponent during repetitive liftings in relation to risk level, as well as to evaluate its ability to discriminate these risk levels. METHODS: Fifteen healthy volunteers performed fatiguing lifting tasks at three different frequencies corresponding to low, medium, and high risk levels according to the National Institute for Occupational Safety and Health (NIOSH) equation. We investigated changes in spinal stability during fatiguing lifting tasks at different risk levels using the maximum Lyapunov's index (λMax) computed from trunk accelerations recorded by placing three IMUs at pelvis, lower and upper spine levels. A two-way repeated-measures ANOVA was performed to determine if there was any significant effect on λMax among the three risk levels and the time (start, mid, and end of the task). Additionally, we examined the Pearson's correlation of λMax with the trunk muscle co-activation, computed from trunk sEMG. RESULTS: Our findings show an increase in trunk stability with increasing risk level and as the lifting task progressed over time. A negative correlation between λMax and trunk co-activation was observed which illustrates that the increase in spinal stability could be partially attributed to increased trunk muscle co-activation. SIGNIFICANCE: This study highlights the possibility of generating stability measures from kinematic data as risk assessment features in fatiguing tasks which may prove useful to detect the risk of developing work-related low back pain disorders and allow the implementation of early ergonomic interventions.
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Remoção , Fadiga Muscular , Humanos , Fadiga Muscular/fisiologia , Tronco/fisiologia , Músculo Esquelético/fisiologia , Coluna Vertebral/fisiologia , Fadiga , Fenômenos Biomecânicos , EletromiografiaRESUMO
Seborrheic keratosis (SK) is the most common benign epidermal tumor in clinical dermatological practice. This review summarizes current knowledge about the clinical and histological appearance, epidemiology, pathogenesis, and treatment of SK. There are different subtypes of SK based on clinical presentation and histologic findings. Several factors, including age, genetic predisposition, and possibly also exposure to ultraviolet radiation, are thought to contribute to the development of SK. The lesions can occur on all areas of the body except for the palms and soles, but the most common sites are the face and upper trunk. The diagnosis is usually made clinically, and in some cases by dermatoscopy or histology. Many patients prefer to have the lesions removed for cosmetic reasons although there is no medical indication. Treatment options include surgical therapy, laser therapy, electrocautery, cryotherapy, and topical drug therapy, which is currently in development. Treatment should be individualized depending on the clinical picture and patient preference.
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Ceratose Seborreica , Humanos , Ceratose Seborreica/diagnóstico , Ceratose Seborreica/terapia , Ceratose Seborreica/patologia , Raios Ultravioleta , Crioterapia , TroncoRESUMO
The aim of this study was to develop a Spanish Version of the Trunk Measurement Scale (TCMS-S) to analyze its validity and reliability and determine the Standard Error of Measurement (SEM) and Minimal Detectable Change (MDC) in children with Cerebral Palsy (CP). Participants were assessed twice 7-15 days apart with the TCMS-S and once with the Gross Motor Function Measurement-88 (GMFM-88), Pediatric Disability Inventory-Computer Adaptive Test (PEDI-CAT), Cerebral Palsy Quality of Life (CPQoL), and Gross Motor Classification System (GMFCS). Internal consistency was evaluated using Cronbach's alpha, and the intraclass correlation (ICC) and kappa coefficients were used to investigate the agreement between the assessments. Finally, 96 participants with CP were included. The TCMS-S showed excellent internal consistency (Cronbach's alpha = 0.95 [0.93 to 0.96]); was highly correlated with the GMFM-88 (rho = 0.816) and the "mobility" subscale of the PEDI-CAT (rho = 0.760); showed a moderate correlation with the "feeling about functioning" CPQoL subscale (rho = 0.576); and differentiated between the GMFCS levels. Excellent test-retest agreement was found for the total and subscale scores (ICC ≥ 0.94 [0.89 to 0.97). For the total TCMS-S score, an SEM of 1.86 and an MDC of 5.15 were found. The TCMS-S is a valid and reliable tool for assessing trunk control in children with CP.
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Paralisia Cerebral , Humanos , Psicometria , Reprodutibilidade dos Testes , Qualidade de Vida , Comparação Transcultural , Tronco , Avaliação da DeficiênciaRESUMO
No epidemiological information about truncal acne is available. This study assessed the self-reported impact of truncal acne in adolescents and young adults, using an internet survey in France in 1,001 adolescents and young adults with truncal acne. Participants' mean age was 18.6 ± 4.3 years, 75.7% were females, 52.9% reported severe and 16.0% very severe truncal acne; 90.0% of participants with truncal acne also reported past or ongoing facial acne. Stress (46.3%), a diet high in lipids (33.2%), and sleeplessness (27.0%) were considered to be triggers of truncal acne; 44.7% consulted at least 1 healthcare professional and 28.1% searched the internet or social network for information about truncal acne. Of subjects with truncal acne, 68.4% thought constantly about their condition. Overall, 79.9% of the participants with severe acne vs 41.8% with mild or moderate acne: 41.8% thought about their acne all the time (p < 0.0001). Truncal acne heavily or very heavily impacted quality of life of 38.7% of participants. It impacted females significantly more than males (p < 0.0001). Significantly (p < 0.001) more females than males reported facial acne. A significant (p = 0.0067) association was observed between the severities of facial and truncal acne. The self-perceived impact of truncal acne in adolescents and young adults highlights the need for information as well as reinforced medical and psychological care.
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Acne Vulgar , Qualidade de Vida , Masculino , Feminino , Humanos , Adolescente , Adulto Jovem , Adulto , Autorrelato , Acne Vulgar/epidemiologia , Tronco , PercepçãoRESUMO
Viewing one's body and even a fake/virtual body experienced as one's own has been suggested to modulate pain perception. However, what happens to pain perception when one's own body part is felt as not belonging to one? We designed a paradigm to induce an illusory feeling of disownership regarding one's limb, investigating whether the feeling affects pain threshold. Participants observed right-side images of their bodies from a third-person perspective via a head-mounted display in real-time. Following instructions, they moved their left hand while keeping their left elbow behind the upper body, so that the connection of their arm to the torso was not visible (test condition), or in front of it, so they could see the arm being part of them (control condition). Then, pain threshold was tested with a thermal stimulator. We found a significantly higher strength of disownership in the test condition than in the control condition. While there was no pain modulation within and between conditions, disownership ratings negatively correlated with pain-threshold changes, where the participants reporting explicit disownership showed lower pain-threshold changes than the others. The finding suggests that while multisensory disintegration had no modulatory effect, the individual sense of disownership was associated with pain perception.
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Ilusões , Humanos , Percepção da Dor , Dor , Tronco , MãosRESUMO
INTRODUCTION: 3D Non-Contact surface scanning (3DSS) is used in both biomechanical and clinical studies to capture accurate 3D images of the human torso, and to better understand the shape and posture of the spine-both healthy and pathological. This study sought to determine the efficacy and accuracy of using 3DSS of the posterior torso, to determine the curvature of the spinal column in the lateral lying position. METHODS: A cohort of 50 healthy adults underwent 3DSS and Magnetic Resonance Imaging (MRI) to correlate the contours of the external spine surface with the internal spinal column. The correlation analysis was composed of two phases: (1) MRI vertebral points vs MRI external spine surface markers; and (2) MRI external spine surface markers vs 3DSS external spine surface markers. The first phase compared the profiles of fiducial markers (vitamin capsules) adhered to the skin surface over the spinous processes against the coordinates of the spinous processes-assessing the linear distance between the profiles, and similarity of curvature, in the sagittal and coronal planes. The second phase compared 3DSS external spine surface markers with the MRI external spine surface markers in both planes, with further qualitative assessment for postural changes. RESULTS: The distance between the MRI vertebral points and MRI external spine surface markers showed strong statistically significant correlation with BMI in both sagittal and coronal planes. Kolmogorov-Smirnov (KS) tests showed similar no significant difference in curvature, k, in almost all participants on both planes. In the second phase, the coronal 3DSS external spine surface profiles were statistically different to the MRI external spine surface markers in 44% of participants. Qualitative assessment showed postural changes between MRI and 3DSS measurements in these participants. CONCLUSION: These study findings demonstrate the utility and accuracy of using anatomical landmarks overlaid on the spinous processes, to identify the position of the spinal bones using 3DSS. Using this method, it will be possible to predict the internal spinal curvature from surface topography, provided that the thickness of the overlaying subcutaneous adipose layer is considered, thus enabling postural analysis of spinal shape and curvature to be carried out in biomechanical and clinical studies without the need for radiographic imaging.
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Escoliose , Curvaturas da Coluna Vertebral , Adulto , Humanos , Escoliose/diagnóstico por imagem , Coluna Vertebral/diagnóstico por imagem , Curvaturas da Coluna Vertebral/diagnóstico por imagem , Radiografia , TroncoRESUMO
PURPOSE: There is strong evidence supporting the presence of fluctuating asymmetry (FA) in Adolescents with Idiopathic Scoliosis (AIS). Additionally, recent research investigating the relationship between vitamin D and AIS found a relation between them. We hypothesize a negative correlation between FA and vitamin D. METHODS: We performed a surface scan of the torso of 53 AIS patients, a blood test to measure vitamin D and the radiographic Cobb angle. A correlation analysis between vitamin D and FA was carried out to test our hypothesis, and a regression of vitamin D on 3D shape was performed to observe shape differences between the vitamin D deficiency and insufficiency groups. RESULTS: There was no correlation between vitamin D and FA. We found a strong negative correlation between vitamin D and the Cobb angle only in the premenarche group (n = 7; r = - 0.92). Differences in shape were observed between the deficiency and insufficiency groups, and that differences were related to the width of the torso, but not the rotation or lateral flexion. CONCLUSIONS: Our results do not support the massive screening of vitamin D in AIS. Shape analysis revealed differences between the shape of the deficiency and insufficiency groups related to robustness. However, this finding had no relation with the scoliosis characteristics, it just reflected different body composition, and its importance should be explored in future.
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Cifose , Escoliose , Humanos , Adolescente , Escoliose/diagnóstico por imagem , Vitamina D , Estudos Prospectivos , Estudos Transversais , TroncoRESUMO
The electrocardiogram (ECG) is the standard method in clinical practice to non-invasively analyze the electrical activity of the heart, from electrodes placed on the body's surface. The ECG can provide a cardiologist with relevant information to assess the condition of the heart and the possible presence of cardiac pathology. Nonetheless, the global view of the heart's electrical activity given by the ECG cannot provide fully detailed and localized information about abnormal electrical propagation patterns and corresponding substrates on the surface of the heart. Electrocardiographic imaging, also known as the inverse problem in electrocardiography, tries to overcome these limitations by non-invasively reconstructing the heart surface potentials, starting from the corresponding body surface potentials, and the geometry of the torso and the heart. This problem is ill-posed, and regularization techniques are needed to achieve a stable and accurate solution. The standard approach is to use zero-order Tikhonov regularization and the L-curve approach to choose the optimal value for the regularization parameter. However, different methods have been proposed for computing the optimal value of the regularization parameter. Moreover, regardless of the estimation method used, this may still lead to over-regularization or under-regularization. In order to gain a better understanding of the effects of the choice of regularization parameter value, in this study, we first focused on the regularization parameter itself, and investigated its influence on the accuracy of the reconstruction of heart surface potentials, by assessing the reconstruction accuracy with high-precision simultaneous heart and torso recordings from four dogs. For this, we analyzed a sufficiently large range of parameter values. Secondly, we evaluated the performance of five different methods for the estimation of the regularization parameter, also in view of the results of the first analysis. Thirdly, we investigated the effect of using a fixed value of the regularization parameter across all reconstructed beats. Accuracy was measured in terms of the quality of reconstruction of the heart surface potentials and estimation of the activation and recovery times, when compared with ground truth recordings from the experimental dog data. Results show that values of the regularization parameter in the range (0.01-0.03) provide the best accuracy, and that the three best-performing estimation methods (L-Curve, Zero-Crossing, and CRESO) give values in this range. Moreover, a fixed value of the regularization parameter could achieve very similar performance to the beat-specific parameter values calculated by the different estimation methods. These findings are relevant as they suggest that regularization parameter estimation methods may provide the accurate reconstruction of heart surface potentials only for specific ranges of regularization parameter values, and that using a fixed value of the regularization parameter may represent a valid alternative, especially when computational efficiency or consistency across time is required.
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Eletrocardiografia , Coração , Animais , Cães , Coração/diagnóstico por imagem , Tronco , Eletricidade , EletrodosRESUMO
According to data, 60-70% of the world's population experience low-back pain (LBP) at least once during their lifetime, often at a young or middle age. Those affected are at risk of having worse quality of life, more missed days at work, and higher medical care costs. We present a new rehabilitation method that helps collect and analyze data on an ongoing basis and offers a more personalized therapeutic approach. This method involves assessing lumbar spine rotation (L1-L5) during torso movement using an innovative dynamic spine correction (DSC) device designed for postural neuromuscular reeducation in LBP. Spinal mobility was tested in 54 patients (aged 18 to 40 years) without LBP. Measurements were made with 12-bit rotary position sensors (AS5304) of the DSC device. During exercise, the mean lumbar spine rotation to the right was greater (4.78° ± 2.24°) than that to the left (2.99° ± 1.44°; p < 0.001). Similarly, the maximum rotation to the right was greater (11.35° ± 3.33°) than that to the left (7.42° ± 1.44°; p < 0.0001). The measurements obtained in the study can serve as a reference for future therapeutic use of the device.
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Dor Lombar , Qualidade de Vida , Pessoa de Meia-Idade , Humanos , Coluna Vertebral , Região Lombossacral , Dor Lombar/terapia , TroncoRESUMO
This study investigated the influence of two different devices with lower torso sports training in patients with asthma. Patients with asthma (n = 300) aged 55-60 years with FEV1/FVC ratio < 65%, who were repeatedly admitted to a pulmonary rehabilitation centre, participated. Patients were evaluated and randomized into two groups (experimental group 1; EXP-1, n = 150, who applied a conventional threshold loading device, and experimental group 2; EXP-2, n = 150, who used an innovative respiratory training device). Patients were included only if they met the global criteria for asthma. The experimental intervention period lasted 10 weeks with 3 weekly training sessions lasting 30-40 min. The maximal inspiratory pressure (PI, max), pulmonary function test, baseline dyspnoea index (BDI), oxygen saturation, and 6 min walking test (6MWT) performance were all measured at baseline and postintervention. Also, an assessment of the 1 min repeated exercise performance (leg extension and leg press) was performed. Moreover, St. George Respiratory Questionnaire was used to quantify the quality of life (SGRQ). Statistical analysis displayed significant favourable effects on 6MWT, leg press, and FRV1, for patients using both devices (EXP-1 and EXP-2, respectively) with lower torso athletic training. The other variables, weight SPO2 and SGRO, also showed no significant change in neither EXP-1 nor EXP-2. Thus, the new respiratory training device (EXP-2) appeared to be as effective as the conventional threshold loading device (EXP-1). In conclusion, our findings demonstrated beneficial effects of combining respiratory training with athletic training in asthma patients. Additionally, the validity of a unique respiratory training device for asthma patients was confirmed.
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Asma , Transtornos Respiratórios , Doenças Respiratórias , Esportes , Humanos , Qualidade de Vida , Asma/terapia , TroncoRESUMO
BACKGROUND: Adolescent idiopathic scoliosis (AIS) curves of 50° to 75° are inclined to progress and are thus indicated for surgery. Nevertheless, the natural history of curves of 40° to 50° following skeletal maturity remains uncertain and presents a clinical dilemma. The aim of this study was to determine the prevalence, rate, and prognostic indicators of curve progression within this patient group. METHODS: This was a retrospective study of 73 skeletally mature patients with AIS. Following yearly or more frequent follow-up, patients were stratified as having no progression (<5° increase) or progression (≥5° increase). Those with progression were further differentiated as having standard progression (<2° increase/year) or fast progression (≥2° increase/year). Radiographic parameters (coronal balance, sagittal balance, truncal shift, apical translation, T1 tilt, apical vertebral wedging) and height were determined on skeletal maturity. Parameters that were significantly associated with progression were subject to receiver operating characteristic (ROC) curve analysis. RESULTS: The average period of post-maturity follow-up was 11.8 years. The prevalence of progression was 61.6%. Among those with progression, the curve increased by a mean of 1.47° ± 1.22° per year, and among those with fast progression, by 3.0° ± 1.2° per year. Thoracic apical vertebral wedging (concave/convex vertebral height × 100) was more apparent in those with progression than in those without progression (84.1 ± 7.5 versus 88.6 ± 3.1; p = 0.003). Increased coronal imbalance (C7 plumb line to central sacral vertebral line) differentiated those with fast progression from others (16.0 ± 11.0 versus 8.7 ± 7.7 mm; p = 0.007). An ROC curve of height-corrected coronal balance demonstrated an area under the curve (AUC) of 0.722, sensitivity of 75.0%, and specificity of 72.5% in identifying fast progression. An ROC curve of height-corrected coronal balance together with apical vertebral wedging to identify those with progression demonstrated an AUC of 0.746, with specificity of 93.7% and sensitivity of 64.5%. CONCLUSIONS: While the majority of curves progressed, the average rate of progression was slow, and thus, yearly observation was a reasonable management approach. Upon validation in larger cohorts, apical wedging and coronal imbalance may identity patients suited for closer monitoring and early spinal fusion. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.
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Cifose , Escoliose , Fusão Vertebral , Humanos , Adolescente , Escoliose/diagnóstico por imagem , Escoliose/cirurgia , Estudos Retrospectivos , Vértebras Torácicas/cirurgia , Tronco , Resultado do Tratamento , Vértebras Lombares/cirurgiaRESUMO
Home-based exercises have been on the rise recently. This pilot study aimed to assess the adherence and effect of a home-based rehabilitation programme using telemonitoring in patients with chronic non-specific low back pain (CNLBP). Twenty-seven patients with CNLBP were enrolled in the study, each of whom underwent a neurological assessment, including patient-oriented measures and a functional assessment-a battery of tests that comprehensively evaluated trunk muscle function. The rehabilitation programme lasted 18 weeks and included daily home-based exercises. A mobile application or an exercise diary was used to monitor compliance. Adherence to the programme was excellent for both the diary and mobile application groups, with 82.3% in the diary group exercising at least once a day and 72.9% twice a day, and 94.8% in the mobile application group exercising at least once a day and 86.6% twice a day. Both patient-oriented and functional outcomes improved significantly; however, the relative changes of the parameters in these two groups did not correlate, which supports the idea that trunk muscle function does not directly relate to patient complaints and that CNLBP is a multifactorial issue. This model of rehabilitation programme should be used in clinical practice, as its adherence and effectiveness seem noticeable.
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Dor Crônica , Dor Lombar , Humanos , Dor Lombar/reabilitação , Projetos Piloto , Terapia por Exercício , Modalidades de Fisioterapia , Tronco , Resultado do TratamentoRESUMO
INTRODUCTION: Hard armour plates provide coverage to essential anatomical structures in the torso that, if injured, would likely be responsible for death before damage control surgery can be undertaken. Existing front and rear OSPREY plates in conjunction with Mark 2 plates used at the sides in current UK Armed Forces personal armour systems are provided in a single size, used by both female and male users. METHODS: CT scans of 45 female UK military personnel were analysed. Distances between anatomical structures representing threshold (absolute minimum) and objective (the maximum level of coverage beyond which there is limited further benefit) coverage of the torso were determined and compared with OSPREY and Mark 2 plate dimensions. Sample characteristics were compared with the 2006/2007 UK Armed Forces Anthropometric Survey. RESULTS: No statistical difference was found between sample means for stature (p=0.131) and mass (p=0.853) from those of the anthropometric survey in this sample. The height of both the front OSPREY plates exceeded the threshold coverage (suprasternal notch to lower border of the 10th rib) for all women studied. The height of the Mark 2 plate exceeds the objective coverage from the side for all women studied. CONCLUSIONS: Based on a plate height providing threshold coverage of all women up to the 50th percentile, the height of the front and rear OSPREY plates could be reduced by 36mm and 31mm respectively. Based on a presumption that a side plate should cover up to the 95th percentile, the Mark 2 plate achieves the objective height and width for the female population studied. Strong evidence was found to support the UK Ministry of Defence requirement for procurement of new front and rear plates of multiple heights for both female and male users.
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Militares , Humanos , Masculino , Feminino , Tronco , Tomografia Computadorizada por Raios X , Reino UnidoRESUMO
Muscle synergy analysis is useful for investigating trunk coordination patterns based on the assumption that the central nervous system reduces the dimensionality of muscle activation to simplify movement. This study aimed to quantify the variability in trunk muscle synergy during various trunk motor tasks in healthy participants to provide reference data for evaluating trunk control strategies in patients and athletes. Sixteen healthy individuals performed 11 trunk movement and stability tasks with electromyography (EMG) recording of their spinal and abdominal muscles (6 bilaterally). Non-negative matrix factorization applied to the concatenated EMG of all tasks identified the five trunk muscle synergies (W) with their corresponding temporal patterns (C). The medians of within-cluster similarity defined by scalar products in W and rmax coefficient using the cross-correlation function in C were 0.73-0.86 and 0.64-0.75, respectively, while the inter-session similarities were 0.81-0.96 and 0.74-0.84, respectively. However, the lowest and highest values of both similarity indices were broad, reflecting the musculoskeletal system's redundancy within and between participants. Furthermore, the significant differences in the degree of variability between the trunk synergies may represent the different neural features of synergy organization and strategies to overcome the various mechanical demands of a motor task.
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Movimento , Músculo Esquelético , Humanos , Músculo Esquelético/fisiologia , Movimento/fisiologia , Eletromiografia , Músculos Abdominais/fisiologia , TroncoRESUMO
Heavy deadlift is used as a physical fitness screening tool in the U.S. Army. Despite the relevance of such a screening tool to military tasks performed by Service Members, the biomechanical impact of heavy deadlift and its risk of low-back injury remain unknown. A kinematics-driven musculoskeletal model of spine was implemented to investigate biomechanics of the lower back in a volunteer (23 years old, height of 1.82 m, and body mass of 98.8 kg) during a 68 kg deadlift. In search of protective mechanisms, effects of model personalization and variations in trunk musculature and lumbopelvic rhythm were also investigated. The net moment, compression and shear forces at the L5-S1 reached peaks of 684 Nm, 17.2 and 4.2 kN, respectively. Geometrical personalization and changes in lumbopelvic rhythm had the least effects on predictions while increases in muscle moment arms (40%) had the largest effects that caused, respectively, 32% and 36% decrease in the maximum compressive and shearing forces. Initiating wrapping of back muscles at farther distances from the spine had opposing effects on spinal loads; peak compression at the L5-S1 decreased by 12% whereas shear increased by 19%. Despite mechanisms considered, spinal loads during heavy deadlift exceed the existing evidence concerning the threshold of injury for spinal segments, suggesting the vulnerability to injury. Chronic exposure to such high-spinal loads may lead to (micro) fractures, degeneration, pathoanatomical changes and finally low-back pain.
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Postura , Coluna Vertebral , Humanos , Adulto Jovem , Adulto , Postura/fisiologia , Coluna Vertebral/fisiologia , Tronco/fisiologia , Músculo Esquelético/fisiologia , Fenômenos Biomecânicos/fisiologia , Suporte de Carga/fisiologia , Vértebras LombaresAssuntos
Paralisia Cerebral , Esportes , Humanos , Criança , Músculo Esquelético , Exercício Físico , TroncoRESUMO
Objective monitors such as the activPAL characterize time when the thigh is horizontal as sedentary time. However, there are physiological differences between lying, bent-legged sitting, and straight-legged sitting. We introduce a three-monitor configuration to assess detailed sedentary postures and demonstrate its use in characterizing such positions in free-living conditions. We explored time spent in each sedentary posture between prolonged (>1 h) versus non-prolonged (<1 h) sedentary bouts. In total, 35 healthy adults (16â, 24 ± 3 years; 24 h/day for 6.8 ± 1.0 days) wore an activPAL accelerometer on their thigh, torso, and shin. Hip and knee joint flexion angle estimates were determined during sedentary bouts using the dot-product method between the torso−thigh and thigh−shin, respectively. Compared to lying (69 ± 60 min/day) or straight-legged sitting (113 ± 100 min/day), most time was spent in bent-legged sitting (439 ± 101 min/day, p < 0.001). Most of the bent-legged sitting time was accumulated in non-prolonged bouts (328 ± 83 vs. 112 ± 63 min/day, p < 0.001). In contrast, similar time was spent in straight-legged sitting and lying between prolonged/non-prolonged bouts (both, p > 0.26). We document that a considerable amount of waking time is accumulated in lying or straight-legged sitting. This methodological approach equips researchers with a means of characterizing detailed sedentary postures in uncontrolled conditions and may help answer novel research questions on sedentariness.
