Functionality-Driven Musculature Retargeting

We present a novel retargeting algorithm that transfers the musculature of a reference anatomical model to new bodies with different sizes, body proportions, muscle capability, and joint range of motion while preserving the functionality of the original musculature as closely as possible. The geometric configuration and physiological parameters of musculotendon units are estimated and optimized to adapt to new bodies. The range of motion around joints is estimated from a motion capture dataset and edited further for individual models. The retargeted model is simulation-ready, so we can physically simulate muscle-actuated motor skills with the model. Our system is capable of generating a wide variety of anatomical bodies that can be simulated to walk, run, jump and dance while maintaining balance under gravity. We will also demonstrate the construction of individualized musculoskeletal models from bi-planar X-ray images and medical examinations.Comment: 15 pages, 20 figure

Bone strength, load tolerance and injury risk in elite Australian football

A paucity of research exists to characterise and investigate lower-body musculoskeletal characteristics and morphological adaptations in elite Australian Footballers with the aim to improve screening, monitoring and load management practices. Given the high prevalence of lower-body skeletal injuries in Australian Football; and the ability to measure, modify and train muscle and bone strength and their derivatives; this project served to extend scientific understanding of musculoskeletal morphology and bone strength characteristics in elite level field-based team sport athletes through a series of research studies using Dual-energy X-ray Absorptiometry (DXA) and peripheral Quantitative Computed Tomography (pQCT). In particular, studies one and two provided normative and comparative lower-body musculoskeletal profiles of elite Australian Footballers, stratified by training age (exposure), limb function (asymmetry) and injury incidence (stress fracture), while study three quantified the morphological changes and magnitude of adaptation and maladaptation experienced by Australian Footballers following an in-season and off-season annual phase. The general conclusion provided by the collective studies of this thesis promotes the importance of bone structure and geometry as potent contributors to skeletal robustness, and bone strength. Athletes with higher levels of training exposure and greater physical resilience exhibited higher tibial mass and cortical density with thicker cortical walls and larger muscle and bone cross-sectional areas. Asymmetrical adaptations from differential loading patterns between limbs through-out an in-season and off-season generate vastly different unilateral load tolerance capabilities when extrapolated overtime. The high-impact gravitational loads experienced by the support limb appear to optimise the development of robust skeletal properties specific to bone structure and geometry which may serve as a loading model to prophylactically enhance bilateral musculoskeletal strength and resilience. Study one provided a set of normative and comparative lower-body musculoskeletal values to describe and compare muscle and bone morphology between less experienced and more experienced athletes (training age); and differential loading patterns between the kicking and support limbs (limb function). Fifty-five athletes were stratified into less experienced (≤ 3 years; n = 27) and more experienced (\u3e 3 years; n = 28) groups in accordance with their training age. All athletes underwent whole-body DXA scans and lower-body pQCT tibial scans on the kicking and support limbs respectively. More experienced players exhibited greater tibial mass, trabecular vBMD, cortical vBMD and total vBMD (p \u3c 0.009; d ≥ 0.79); greater cortical thickness and cortical area (p \u3c 0.001; d ≥ 0.92), and larger stress-strain indices and absolute fracture loads (p ≤ 0.018; d ≥ 0.57) than less experienced players. More experienced players also exhibited greater muscle mass and muscle cross-sectional area (p ≤ 0.016; d ≥ 0.68). Differences were also observed between limbs, with greater material (tibial mass and cortical vBMD), structural (trabecular area, cortical area, total area, periosteal area and cortical thickness) and strength (stress-strain index and absolute fracture load) characteristics evident in the support leg comparative to the kicking leg of more experienced players (d ≥ 0.20); with significantly higher asymmetries in tibial mass and cross-sectional area evident in more experienced players than less experienced players as a product of limb function over time. The findings of this study illustrate that training exposure and continued participation in Australian Football produced greater lower-body material, structural and strength adaptations; with chronic exposure to asymmetrical loading patterns developing differential morphological changes between the kicking and support Study two provided a retrospective and comparative set of lower-body musculoskeletal data to describe and compare muscle and bone morphology between injured and non-injured Australian Football athletes, in addition to injured and non-injured limbs within injured players, in order to identify musculoskeletal characteristics which may predispose athletes to stress fractures or highlight skeletal fragility. Fifty-five athletes were stratified into injured (n = 13) and non-injured (n = 42) groups. All athletes underwent whole-body DXA scans and lower-body pQCT tibial scans across both limbs. Injured players exhibited lower tibial mass (p ≤ 0.019; d ≥ 0.68), cortical vBMD (d ≥ 0.38) and marrow vBMD (d ≥ 0.21); smaller cortical area and periosteal area (p ≤ 0.039; d ≥ 0.63); smaller trabecular area, marrow area, total area, endocortical area and cortical thickness (d ≥ 0.22); lower stress-strain indices, absolute fracture loads and relative fracture loads (support leg: p ≤ 0.043; d ≥ 0.70, kicking leg: d ≥ 0.48) than non-injured players. Injured players also exhibited lower muscle cross-sectional area and muscle mass (p ≤ 0.034; d ≥ 0.79), yet higher muscle density (d ≥ 0.28) than non-injured players. Differences between injured and non-injured limbs internal to injured players were also observed, with lower material (tibial mass and total vBMD), structural (cortical area and cortical thickness) and strength (stress-strain index and relative fracture load) in the injured limb comparative to the non-injured limb (d = 0.20 – 0.70). Muscle density was lower in the injured limb (d = 0.54). The findings of this study illustrate a general inferiority and global musculoskeletal weakness in injured players, with non-injured players ~10-12% stronger across both limbs. Injured players were skeletally slender with smaller muscle and bone cross-sectional areas and thinner cortices. Similarly, injured limbs of injured players also exhibited smaller structural proportions, highlighting the importance of cortical area and cortical thickness as key structural and geometric skeletal properties with potent contributions to bone strength and resilience. limbs. Indeed, routine high-impact, gravitational load afforded to the support limb preferentially improves bone structure and geometry (cross sectional area and thickness) as potent contributors to bone strength and skeletal fatigue resistance. Study three provided a seasonal investigation into lower-body musculoskeletal adaptations over the course of a ~26 week in-season and ~10 week off-season period in Australian Football. Forty athletes (n = 40) and twenty-two athletes (n = 22) were recruited to quantify morphological changes in muscle and bone following the in-season and off-season periods respectively. All athletes underwent whole-body DXA scans and lower-body pQCT tibial scans for the kicking and support limbs at the commencement and conclusion of each season. Australian Football athletes exhibited increases in trabecular vBMD, total vBMD and cortical thickness in the kicking leg; with increased cortical vBMD, total vBMD, trabecular area, total area, periosteal area, cortical thickness and reduced endocortical area in the support leg following the in-season period. Percent changes between limbs were significantly different for trabecular vBMD, cortical vBMD, total vBMD and trabecular area (p ≤ 0.049; d ≥ 0.46), despite similar increments in bone strength (~44 – 50 N), demonstrating asymmetrical morphological responses to differential loading patterns in-season. Conversely, Australian Football athletes exhibited material decreases in tibial mass, trabecular vBMD, cortical vBMD and total vBMD in both limbs over the off-season by similar yet opposite magnitudes to the benefits accrued during the in-season, in addition to reduced muscle area, highlighting a general musculoskeletal de-training effect. Structural adaptations were mostly maintained or increased for both limbs over the off-season, with bone strength completely reversed in the kicking leg, yet wholly preserved in the support leg; a lasting adaptation from regular high-impact, gravitational loading specific to the support leg. The findings of this study illustrate the osteogenic potential of a ~26 week in-season, and the de-training potential of a ~10 week off-season. Specifically, the kicking and support limbs continued to show asymmetrical morphological adaptations to differential in-season and off-season loading and de-loading patterns

Commentary: Evaluating the role of seagrass in Cenozoic CO2 variations

[No abstract available

An investigation into somatic pain and human behaviour

The present study is an investigation of the theory that some muscular pains, so- called fibrositis, muscular rheumatism, etc., are of "psychogenic" origin.That psychological factors are involved in the causation of muscular pain is supported by considerable evidence. There is the relative absence of tissue pathology in these muscular pains; there is the fact that a muscle is almost, if not quite, painless to direct muscle stimu- lation, i.e. cuttin$,pushing needles through, burning, scratching etc. (although it may become a source of pain under other conditions) ; there is the unanimous opinion that the main symptom in muscular pain is muscle spasm; and finally there is the empirical observation that patients with muscular pains located in similar structures display similar behavioural patterns and that pain "fluctuates" from day to day in accordance with fluctuations of life situations.All this supports the proposition that a behavioural investigation of muscular pain would be best suited to solve many problems, about which numerous speculative theories have been advanced.In order to make it possible to formulate a hypo- thesis and submit it to a scientific test, two preliminary investigations were carried out: i. Physical Investigation 2. Physchological InvestigationThe clinical findings from these two investigations were conceptualised and a hypothesis and a working plan for testing it were elaborated.The present investigation was primarily a psycho-physical investigation but it differed from the prevailing psychosomatic approach in breaking with the tradition of mind-body dualism. The individual was instead regarded as a biological organism operating in, and by means of, an individually- determined physical and social environment.The postulated aims of this inquiry were: (a) to establish the most probable relationship between muscular spasm (a symptom widely observed) and muscular pain; (b) to find out what stimulus was most likely to bring about this "involuntary" muscle contraction; (c) to examine the relationship between muscular pain and life situations; (d) to make inferences as to the underlying neuro-physiological mechanisms involved in muscular pains.As the investigation was based on clinical material, the prevailing method had to be the clinical method - a procedure directed towards the individual and his "problems ". This method seemed to be a suitable basic method for obtaining the necessary information as to when and under what conditions behaviour occurs,The obtained results confirmed the assumption that muscular pain may constitute a behaviour disorder, although physical factors cannot be excluded from the aetiology of pain. It is the interplay between behavioural and physical factors that is responsible for muscular pain occurrence.In addition this investigation has thrown some light on the neuro -physiological factors involved in muscular pain and has also furnished some practical information as to the most successful approach in treatment of muscular pain

Avaliação ecográfica da morfologia muscular perante situações de sobrecarga agudas e crónicas

Introduction: Ultrasound (US) has an important role in musculoskeletal (MSK) evaluation, allowing the study of muscle morphology and function. Muscle thickness (MT) and muscle echo-intensity (EI) are two important parameters that may quantify muscle structural adaptations to a variety of stimuli. US elastography can also offer semi-quantitative and/or quantitative assessment of tissue stiffness providing relevant information about adaptations of muscle mechanical properties. Purpose: The general aim of the studies presented in this thesis is to explore the potential of quantitative US imaging for assessing the adaptations and responses of the muscle tissue to increased contractile activity using B-mode US and US elastography. The studies were centred on the quadriceps femoris muscle and addressed the study of the effect of strength training and of acute muscle contractile activity on MT, EI and muscle stiffness. Materials and methods: Three different studies were conducted and reported along this thesis. A total of 64 young adults of both genders participated in the studies. The first study (N = 20) evaluated the intra- and inter-session (one week apart) reproducibility of MT and EI parameters and the role of plane of view (transverse vs. longitudinal) and ROI dimension on measurements’ accuracy using the intraclass correlation coefficient [ICC(3,1)], the standard error of measurement (SEM), and the smallest detectable change (SDC). Bland-Altman analysis was used to study the level of agreement between plane views and ROI sizes. The second study (N = 28) investigated the effect of a 15-week strength program on MT and EI in several regions of the heads of the quadriceps femoris. This study included a control group and two training groups performing concentric or eccentric strength training. During this study, changes in vastus lateralis’ (VL) stiffness in response to strength training were evaluated using quasi-static elastography (QSE). In the final study (N = 16), acute changes in VL’s stiffness associated with passive stretching, performance of short but intense contractile activity, and muscle isometric contractions were investigated by means of supersonic shear wave imaging (SSI). Results: Moderate to very high reliability was found for MT (intra-session, ICCs: 0.82- 0.99; inter-session, ICCs: 0.70-0.98) and EI (intra-session, ICCs: 0.74-0.97; inter-session, ICCs: 0.48-0.94). In general, reliability for MT and EI measures was higher in the transverse plane and when using a larger ROI, respectively. Measurements of EI taken with a small versus a large ROI are associated with a small bias and larger limits of Morphological ultrasound evaluation in acute and chronic muscle overloading agreement (LoA). In study 2, 15 weeks of strength training increased MT in the majority but not in all of the scanned regions. Strength training failed in changing EI in most of the quadriceps femoris, excepting in the VI and some regions of the VL. Strength training significantly increased VL’s stiffness. No differences were observed in our quantitative US parameters between concentric and eccentric training. The final study demonstrated an acute increase of around 10% in VL’s shear modulus as a result of performing maximal isometric, concentric, and eccentric contractions. The shear modulus of the VL also increased when the knee moved from 10º to 50º and then to 90º flexion. Finally, a linear relationship between the shear modulus and the level of isometric muscle contraction was observed. Conclusions: Ultrasound measures of MT and EI show moderate to very high reliability. The reliability and agreement of MT and EI measurements are improved in transverse scans and with larger ROIs. QSE could demonstrate an increase in muscle stiffness as a result of strength training. SSI proved to be a good method to investigate muscle mechanical properties changes associated with muscle function. These results emphasise the value of an objective and quantifiable muscle US evaluation for studying muscle adaptation to exercise training and muscle function, in general.Introdução: A ultrassonografia tem um papel importante na avaliação músculoesquelética, permitindo o estudo da morfologia e função muscular. A espessura muscular e a eco- intensidade muscular são dois parâmetros importantes que podem quantificar as adaptações estruturais musculares, quando o musculo é submetido a determinados estímulos. A elastografia por ultrassonografia pode, também, oferecer uma avaliação semi-quantitativa e/ou quantitativa da rigidez do tecido, fornecendo informações relevantes sobre as adaptações das propriedades mecânicas musculares. Objetivo: O objetivo geral, dos estudos apresentados nesta tese, é explorar o potencial da imagem quantitativa ultrassonográfica, de forma a avaliar as adaptações e as respostas do tecido muscular ao aumento da atividade contrátil, usando a elastografia e a ultrassonografia em modo-B. Os estudos foram centrados no músculo do quadricípite femoral e abordaram o estudo do efeito do treino de força e da atividade contrátil muscular na espessura muscular, eco-intensidade e rigidez muscular. Materiais e métodos: Três diferentes estudos foram realizados e descritos ao longo desta tese. Um total de 64 jovens adultos de ambos os géneros participaram dos estudos. No primeiro estudo (N = 20), foi analisada a reprodutibilidade da espessura muscular e da eco-intensidade dos quatro músculos que compõem o quadricípite femoral. Para isso foram adquiridas três imagens em modo B, nos planos longitudinal e transversal, em dois momentos distintos. A eco-intensidade foi medida usando dois tamanhos diferentes de região de interesse, um representado por uma forma retangular, medindo 70 mm2 e um outro representando o máximo do músculo apresentado na imagem ultrassonográfica, evitando as fáscias superficial e profundas do mesmo. A precisão das medidas foi, então, analisada usando o Coeficiente de correlação intra-classe [ICC (3,1)], o erro padrão de medição (SEM) e a menor alteração detectável (SDC). A análise de Bland-Altman foi utilizada para estudar o nível de concordância entre os planos de imagem ultrassonográficos e os diferentes tamanhos da região de interesse. No segundo estudo (N = 28), analisou-se o efeito de um programa de treino de força, com duração de 15 semanas, sobre espessura muscular e ecointensidade em três diferentes regiões de cada um dos quatro músculos que representam o quadricípite femoral: reto femoral, vasto intermédio, vasto medial e vasto lateral. Este estudo incluiu um grupo de controlo e dois grupos de treino, em que um realizou um protocolo de treino concêntrico e o outro de treino excêntrico. Durante este estudo, as alterações na rigidez do vasto lateral, em resposta ao treino de força foram avaliadas usando a elastografia quasi-statica, semi-quantitativa. No último estudo (N = 16), foram analisadas as alterações agudas na rigidez de vasto lateral associadas ao alongamento passivo, ao desempenho de atividade contrátil de curta duração, mas intensa e às contrações isométricas musculares usando a elastografia de onda supersónica por cisalhamento. Resultados: Foi encontrada uma alta ou muito alta reprodutibilidade para espessura muscular (intra-sessão, ICCs: 0,82-0,99; inter-sessão, ICCs: 0,70-0,98) e eco-intensidade (intra-sessão, ICCs: 0,74-0,97; inter-sessão, ICCs: 0,48-0,94). Em geral, a reprodutibilidade para os valores da espessura muscular foi maior no plano transversal e no que diz respeito aos valores da eco-intensidade verificou-se uma melhor reprodutibilidade quando foi utilizada uma região de interesse de maiores dimensões. Um pequeno viés e menores valores de concordância caracterizam as medidas de cointensidade obtidas com uma região de interesse maior ou menor. No estudo 2, os participantes submetidos a 15 semanas de treino de força revelaram o aumento da sua espessura na maioria das regiões musculares avaliadas, mas não em todas. Não foram encontradas alterações significavas dos valores da eco-intensidade com a realização do treino de força na maioria dos músculos do quadricípite femoral, excepto para o vasto intermédio e para algumas regiões do vasto lateral.Por outro lado, o treino de força aumentou significativamente a rigidez do vasto lateral. Não foram observadas diferenças significativas nos parâmetros quantitativos ultrassonográficos entre o treino concêntrico e excêntrico. O último estudo demonstrou um aumento agudo de cerca de10% nos valores da rigidez do vasto lateral como resultado da realização de contrações máximas isométricas, concêntricas e excêntricas. Os valores da rigidez do vasto lateral também aumentaram durante a flexão do joelho de 10º para 50º e posteriormente para 90º. Finalmente, observou-se uma relação linear entre os valores de rigidez do vasto lateral e o nível de contração muscular isométrica do quadricípite femoral. Conclusões: As medidas ultrassonográficas da espessura muscular e eco-intensidade mostram uma reprodutibilidade moderada a muito alta. A reprodutibilidade e a concordância das medidas de espessura muscular e eco-intensidade são maiores no plano transversal e quando é utilizada uma região de interesse de maior dimensão. A elastografia semi-quantitativa mostrou existir um aumento significativo na rigidez muscular como resultado do treino de força. A elastografia por onda de cisalhamento supersónica é um bom método para investigar as alterações das propriedades mecânicas musculares associadas à função muscular. Estes resultados enfatizam a importância de uma avaliação objetiva e quantificável dos músculos por ultrassonografia, para estudar a adaptação muscular ao treino e função muscular, no geral

Characterization of Quadriceps Neuromuscular Function in Knee Osteoarthritis

PURPOSE: The purpose of this thesis was to characterize quadriceps neuromuscular dysfunction in patients with knee osteoarthritis (OA). Concerns pertaining to study design in this patient population (e.g. disease severity criteria and muscle imaging outcome measures) were also addressed. METHODS: Five studies were undertaken using data acquired from volunteers recruited at the local institution and from participants in the public source dataset of the Osteoarthritis Initiative (http://oai.epi-ucsf.org/datarelease/). Clinical disease severity was evaluated with the Western Ontario and McMaster Osteoarthritis Index (WOMAC). Radiographic severity was evaluated with Kellgren-Lawrence Grading (KLG). Quadriceps muscle isometric strength and isotonic power were measured with dynamometry. Voluntary activation (VA) of the quadriceps was determined with the interpolated twitch technique. Information about intrinsic properties of the neuromuscular system were assessed with magnetic resonance imaging (MRI) derived measures of muscle volume, intramuscular and surface electromyography and measurement of evoked contractile properties. RESULTS: Radiographic definition of disease severity displayed a ceiling effect and led to underestimation of quadriceps muscle weakness in patients with knee OA (Chapter 2). Quadriceps muscle isometric strength, velocity and isotonic power were reduced across a clinical spectrum of knee OA, however muscle quality (i.e. specific torque and specific power were unaffected, Chapter 3). Quadriceps whole muscle volume, measured with MRI can be reliably measured and was the primary predictor of isometric strength (Chapter 4). VA deficits were minimal in knee OA patients, even in those with severe knee pain and disability (Chapter 5). No changes in evoked contractile properties were observed across a clinical spectrum of knee OA, however average motor unit size was larger and firing rates slightly lower in patients with knee OA compared to healthy controls (Chapter 6). CONCLUSION: This thesis provided information about the magnitude and mechanisms of quadriceps neuromuscular dysfunction in patients with knee OA, which have consequences with regard to the treatment and prognosis of this disorder. Furthermore, the information provided about the validity of commonly used predictor variables and outcome measures has implications for future study design in this disease population