Influence of inverse dynamics methods on the calculation of inter-segmental moments in vertical jumping and weightlifting

<p>Abstract</p> <p>Background</p> <p>A vast number of biomechanical studies have employed inverse dynamics methods to calculate inter-segmental moments during movement. Although all inverse dynamics methods are rooted in classical mechanics and thus theoretically the same, there exist a number of distinct computational methods. Recent research has demonstrated a key influence of the dynamics computation of the inverse dynamics method on the calculated moments, despite the theoretical equivalence of the methods. The purpose of this study was therefore to explore the influence of the choice of inverse dynamics on the calculation of inter-segmental moments.</p> <p>Methods</p> <p>An inverse dynamics analysis was performed to analyse vertical jumping and weightlifting movements using two distinct methods. The first method was the traditional inverse dynamics approach, in this study characterized as the 3 step method, where inter-segmental moments were calculated in the local coordinate system of each segment, thus requiring multiple coordinate system transformations. The second method (the 1 step method) was the recently proposed approach based on wrench notation that allows all calculations to be performed in the global coordinate system. In order to best compare the effect of the inverse dynamics computation a number of the key assumptions and methods were harmonized, in particular unit quaternions were used to parameterize rotation in both methods in order to standardize the kinematics.</p> <p>Results</p> <p>Mean peak inter-segmental moments calculated by the two methods were found to agree to 2 decimal places in all cases and were not significantly different (p > 0.05). Equally the normalized dispersions of the two methods were small.</p> <p>Conclusions</p> <p>In contrast to previously documented research the difference between the two methods was found to be negligible. This study demonstrates that the 1 and 3 step method are computationally equivalent and can thus be used interchangeably in musculoskeletal modelling technology. It is important that future work clarifies the influence of the other inverse dynamics methods on the calculation of inter-segmental moments. Equally future work is needed to explore the sensitivity of kinematics computations to the choice of rotation parameterization.</p

MODELLING SCAPULAR BIOMECHANICS TO ENHANCE INTERPRETATION OF KINEMATICS AND PERFORMANCE DATA IN ROWING

Rowing involves repetitive, high intensity loading on the glenohumeral joint. Shoulder pain is associated with muscle weakness and imbalance, resulting in long-lasting overuse injuries. The goal of this study was to explore three-dimensional shoulder biomechanics during rowing to identify parameters that influence technique. Eleven athletes had their movement recorded by motion capture while using an instrumented ergometer. Kinetics and kinematics drove a computational model which output joint and muscle forces across the shoulder. Results suggest that subtle muscular changes identified by the model can be sensitively mapped to performance variables. When evaluated alongside ergometer-derived power metrics, biomechanics parameters can provide athletes and coaches a fuller picture of performance potential, injury risk, and training program efficacy

FATIGUE LEADS TO ALTERED SPINAL KINEMATICS DURING HIGH PERFORMANCE ERGOMETER ROWING

Low back injuries in rowing are attributed to intense, repetitive, loading through the spine. Good technique and postural control are essential to maximize performance and minimize injury risk. This motion capture study recorded 3D spinal kinematics of 14 athletes during rowing at varying speeds on an instrumented ergometer and correlated motion with power metrics and athlete demographics. Sagittal plane rotation decreases in the lumbar spine and increases in the thoracic spine as speed increases. Transverse and frontal planes have little influence on force output. Declining postural control can be seen within each trial and worsened with higher rate. Assessments of form differences across athletes using relative motion between spine segments at critical stroke points show greater lumbar flexion (compared to thoracic) at the catch and neutral alignment at max handle force

Differential Cerebral Cortex Transcriptomes of Baboon Neonates Consuming Moderate and High Docosahexaenoic Acid Formulas

BACKGROUND: Docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (ARA, 20:4n-6) are the major long chain polyunsaturated fatty acids (LCPUFA) of the central nervous system (CNS). These nutrients are present in most infant formulas at modest levels, intended to support visual and neural development. There are no investigations in primates of the biological consequences of dietary DHA at levels above those present in formulas but within normal breastmilk levels. METHODS AND FINDINGS: Twelve baboons were divided into three formula groups: Control, with no DHA-ARA; “L”, LCPUFA, with 0.33%DHA-0.67%ARA; “L3”, LCPUFA, with 1.00%DHA-0.67%ARA. All the samples are from the precentral gyrus of cerebral cortex brain regions. At 12 weeks of age, changes in gene expression were detected in 1,108 of 54,000 probe sets (2.05%), with most showing <2-fold change. Gene ontology analysis assigns them to diverse biological functions, notably lipid metabolism and transport, G-protein and signal transduction, development, visual perception, cytoskeleton, peptidases, stress response, transcription regulation, and 400 transcripts having no defined function. PLA2G6, a phospholipase recently associated with infantile neuroaxonal dystrophy, was downregulated in both LCPUFA groups. ELOVL5, a PUFA elongase, was the only LCPUFA biosynthetic enzyme that was differentially expressed. Mitochondrial fatty acid carrier, CPT2, was among several genes associated with mitochondrial fatty acid oxidation to be downregulated by high DHA, while the mitochondrial proton carrier, UCP2, was upregulated. TIMM8A, also known as deafness/dystonia peptide 1, was among several differentially expressed neural development genes. LUM and TIMP3, associated with corneal structure and age-related macular degeneration, respectively, were among visual perception genes influenced by LCPUFA. TIA1, a silencer of COX2 gene translation, is upregulated by high DHA. Ingenuity pathway analysis identified a highly significant nervous system network, with epidermal growth factor receptor (EGFR) as the outstanding interaction partner. CONCLUSIONS: These data indicate that LCPUFA concentrations within the normal range of human breastmilk induce global changes in gene expression across a wide array of processes, in addition to changes in visual and neural function normally associated with formula LCPUFA

High-density EMG, IMU, kinetic, and kinematic open-source data for comprehensive locomotion activities.

Acknowledgements: This study was partly supported by the EPSRC Centre for Doctoral Training in Neurotechnology for Life and by the European Research Council Synergy Grant NaturalBionicS (contract #810346). I would also like to thank Dr Clement Favier for the help in the construction of the stairs and ramps setup along with the CAD drawings.Novel sensor technology enables new insights in the neuromechanics of human locomotion that were previously not possible. Here, we provide a dataset of high-density surface electromyography (HDsEMG) and high-resolution inertial measurement unit (IMU) signals, along with motion capture and force data for the lower limb of 10 healthy adults during multiple locomotion modes. The participants performed level-ground and slope walking, as well as stairs ascent/descent, side stepping gait, and stand-to-walk and sit-to-stand-to-walk, at multiple walking speeds. These data can be used for the development and validation of locomotion mode recognition and control algorithms for prosthetics, exoskeletons, and bipedal robots, and for motor control investigations

Measuring, describing accurately and using force measures on the seat of a rowing ergometer

Examines the process of measuring, describing accurately and using force measures on the seat of a rowing ergometer