scholarly journals An EMG-Driven Biomechanical Model That Accounts for the Decrease in Moment Generation Capacity During a Dynamic Fatigued Condition

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Guillaume Rao ◽  
Eric Berton ◽  
David Amarantini ◽  
Laurent Vigouroux ◽  
Thomas S. Buchanan
Keyword(s):  
Linear Regression ◽  
Production Capacity ◽  
Biomechanical Model ◽  
Joint Moment ◽  
Muscle Group ◽  
Extensor Muscle ◽  
Mean Frequency ◽  
Biomechanical Models ◽  
Fatigued Muscle ◽  
Muscle Groups

Although it is well known that fatigue can greatly reduce muscle forces, it is not generally included in biomechanical models. The aim of the present study was to develop an electromyographic-driven (EMG-driven) biomechanical model to estimate the contributions of flexor and extensor muscle groups to the net joint moment during a nonisokinetic functional movement (squat exercise) performed in nonfatigued and in fatigued conditions. A methodology that aims at balancing the decreased muscle moment production capacity following fatigue was developed. During an isometric fatigue session, a linear regression was created linking the decrease in force production capacity of the muscle (normalized force/EMG ratio) to the EMG mean frequency. Using the decrease in mean frequency estimated through wavelet transforms between dynamic squats performed before and after the fatigue session as input to the previous linear regression, a coefficient accounting for the presence of fatigue in the quadriceps group was computed. This coefficient was used to constrain the moment production capacity of the fatigued muscle group within an EMG-driven optimization model dedicated to estimate the contributions of the knee flexor and extensor muscle groups to the net joint moment. During squats, our results showed significant increases in the EMG amplitudes with fatigue (+23.27% in average) while the outputs of the EMG-driven model were similar. The modifications of the EMG amplitudes following fatigue were successfully taken into account while estimating the contributions of the flexor and extensor muscle groups to the net joint moment. These results demonstrated that the new procedure was able to estimate the decrease in moment production capacity of the fatigued muscle group.

Magnitude and Reliability of Measurements of Muscle Strength across Trials for Individuals with Mental Retardation

1993 ◽  
Vol 77 (2) ◽  
pp. 643-649 ◽  
Author(s):  
Michael Horvat ◽  
Ron Croce ◽  
Glenn Roswal
Keyword(s):  
Mental Retardation ◽  
Muscle Strength ◽  
Muscle Group ◽  
Extensor Muscle ◽  
Reliable Measure ◽  
Muscle Groups ◽  
Sufficient Magnitude ◽  
Individuals With Mental Retardation

The purpose of this investigation was to examine the magnitude and reliability of strength measures on the Nicholas Manual Muscle Tester for individuals with mental retardation. 17 subjects were given six trials with the dominant and nondominant flexor and extensor muscle groups. No significant differences were found between dominant and nondominant muscle groups by side or by muscle group. Interclass correlations ranged from .96 to .98 for six and three trials, respectively. It was concluded that the test was appropriate for reliably assessing strength in this population and that these individuals can achieve a sufficient magnitude on three trials for a reliable measure of strength.

scholarly journals Reduced biomechanical models for precision-cut lung-slice stretching experiments

2021 ◽  
Vol 82 (5) ◽  
Author(s):  
Hannah J. Pybus ◽  
Amanda L. Tatler ◽  
Lowell T. Edgar ◽  
Reuben D. O’Dea ◽  
Bindi S. Brook
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Ex Vivo ◽  
Finite Thickness ◽  
Biomechanical Model ◽  
Local Stress ◽  
Smooth Muscle Contraction ◽  
Biomechanical Models ◽  
Cytokine Activation ◽  
Asymptotic Reduction

AbstractPrecision-cut lung-slices (PCLS), in which viable airways embedded within lung parenchyma are stretched or induced to contract, are a widely used ex vivo assay to investigate bronchoconstriction and, more recently, mechanical activation of pro-remodelling cytokines in asthmatic airways. We develop a nonlinear fibre-reinforced biomechanical model accounting for smooth muscle contraction and extracellular matrix strain-stiffening. Through numerical simulation, we describe the stresses and contractile responses of an airway within a PCLS of finite thickness, exposing the importance of smooth muscle contraction on the local stress state within the airway. We then consider two simplifying limits of the model (a membrane representation and an asymptotic reduction in the thin-PCLS-limit), that permit analytical progress. Comparison against numerical solution of the full problem shows that the asymptotic reduction successfully captures the key elements of the full model behaviour. The more tractable reduced model that we develop is suitable to be employed in investigations to elucidate the time-dependent feedback mechanisms linking airway mechanics and cytokine activation in asthma.

Impact of Age and Body Mass Index on Anthropometry in Working Adults

2017 ◽  
Vol 61 (1) ◽  
pp. 1341-1345 ◽  
Author(s):  
Zachary Merrill ◽  
April Chambers ◽  
Rakié Cham
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Center Of Mass ◽  
Biomechanical Model ◽  
Whole Body ◽  
Working Adults ◽  
Biomechanical Models ◽  
Scan Data ◽  
Body Segment Parameters ◽  
The Impact

Body segment parameters (BSPs) such as segment mass and center of mass are used as inputs in ergonomic design and biomechanical models to predict the risk of musculoskeletal injuries. These models have been shown to be sensitive to the BSP values used as inputs, demonstrating the necessity of using accurate and representative parameters. This study aims to provide accurate BSPs by quantifying the impact of age and body mass index on torso and thigh mass and center of mass in working adults using whole body dual energy x-ray absorptiometry (DXA) scan data. The results showed significant effects of gender, age, and body mass index (BMI) on torso and thigh mass and center of mass, as well as significant effects of age and BMI within genders, indicating that age, gender, and BMI need to be taken into account when predicting BSPs in order to calculate representative ergonomic and biomechanical model outputs.

Perceived Exertion in Isometric Muscular Contractions Related to Age, Muscle, Force Level and Duration

1992 ◽  
Vol 36 (10) ◽  
pp. 712-716 ◽  
Author(s):  
Joseph M. Deeb ◽  
Colin G. Drury
Keyword(s):  
Perceived Exertion ◽  
Muscle Force ◽  
Age Groups ◽  
Muscle Group ◽  
Isometric Contractions ◽  
Age Group ◽  
Perceived Effort ◽  
Muscle Groups ◽  
Different Levels

This research was concerned with studying the development and growth of perceived effort of long-term isometric contractions as a function of muscle group (biceps vs quadriceps), of subjects with different age groups (20–29 vs. 50–59 years old) on long-term muscular isometric contractions (5 minutes) at different levels of %MVC (20, 40, 60, 80 and 100 %MVC). An experiment testing 20 subjects each performing 10 conditions (two muscle groups × five levels of %MVC) showed that the older age group reported Significantly higher perceived exertion at higher levels of %MVC and across time. Furthermore, subjects experienced a higher and faster increase in their perceived exertion when the level of %MVC and time increased.

scholarly journals Characterization of rat tail lymphatic contractility and biomechanics: incorporating nitric oxide-mediated vasoregulation

2020 ◽  
Vol 17 (170) ◽  
pp. 20200598 ◽  
Author(s):  
Mohammad S. Razavi ◽  
J. Brandon Dixon ◽  
Rudolph L. Gleason
Keyword(s):  
Nitric Oxide ◽  
Mechanical Response ◽  
Contractile Function ◽  
Ex Vivo ◽  
Biomechanical Model ◽  
Biomechanical Models ◽  
Lymphatic Pumping ◽  
Rat Tail ◽  
Lymphatic Contractility

The lymphatic system transports lymph from the interstitial space back to the great veins via a series of orchestrated contractions of chains of lymphangions. Biomechanical models of lymph transport, validated with ex vivo or in vivo experimental results, have proved useful in revealing novel insight into lymphatic pumping; however, a need remains to characterize the contributions of vasoregulatory compounds in these modelling tools. Nitric oxide (NO) is a key mediator of lymphatic pumping. We quantified the active contractile and passive biaxial biomechanical response of rat tail collecting lymphatics and changes in the contractile response to the exogenous NO administration and integrated these findings into a biomechanical model. The passive mechanical response was characterized with a three-fibre family model. Nonlinear regression and non-parametric bootstrapping were used to identify best-fit material parameters to passive cylindrical biaxial mechanical data, assessing uniqueness and parameter confidence intervals; this model yielded a good fit ( R 2 = 0.90). Exogenous delivery of NO via sodium nitroprusside (SNP) elicited a dose-dependent suppression of contractions; the amplitude of contractions decreased by 30% and the contraction frequency decreased by 70%. Contractile function was characterized with a modified Rachev–Hayashi model, introducing a parameter that is related to SNP concentration; the model provided a good fit ( R 2 = 0.89) to changes in contractile responses to varying concentrations of SNP. These results demonstrated the significant role of NO in lymphatic pumping and provide a predictive biomechanical model to integrate the combined effect of mechanical loading and NO on lymphatic contractility and mechanical response.

Upper Limb Strength and Muscle Volume in Healthy Middle-Aged Adults

2015 ◽  
Vol 31 (6) ◽  
pp. 484-491 ◽  
Author(s):  
Katherine R. Saul ◽  
Meghan E. Vidt ◽  
Garry E. Gold ◽  
Wendy M. Murray
Keyword(s):  
Functional Groups ◽  
Upper Limb ◽  
Joint Moment ◽  
Muscle Volume ◽  
Middle Aged ◽  
Consistent Manner ◽  
Generating Capacity ◽  
Muscle Groups ◽  
Middle Aged Adults ◽  
Total Muscle

Our purpose was to characterize shoulder muscle volume and isometric moment, as well as their relationship, for healthy middle-aged adults. Muscle volume and maximum isometric joint moment were assessed for 6 functional muscle groups of the shoulder, elbow, and wrist in 10 middle-aged adults (46–60 y, 5M, 5F). Compared with young adults, shoulder abductors composed a smaller percentage of total muscle volume (P = .0009) and there was a reduction in shoulder adductor strength relative to elbow flexors (P = .012). We observed a consistent ordering of moment-generating capacity among functional groups across subjects. Although total muscle volume spanned a 2.3-fold range, muscle volume was distributed among functional groups in a consistent manner across subjects. On average, 72% of the variation in joint moment could be explained by the corresponding functional group muscle volume. These data are useful for improved modeling of upper limb musculoskeletal performance in middle-aged subjects, and may improve computational predictions of function for this group.

MUSCLE GROWTH AND DISTRIBUTION IN SWINE AS INFLUENCED BY LIVEWEIGHT, BREED, SEX AND RATION

1971 ◽  
Vol 51 (1) ◽  
pp. 41-49 ◽  
Author(s):  
R. J. RICHMOND ◽  
R. T. BERG
Keyword(s):  
Muscle Growth ◽  
Growth Patterns ◽  
Muscle Group ◽  
Low Energy ◽  
Limb Muscle ◽  
Thoracic Limb ◽  
Yorkshire Pigs ◽  
Spinal Group ◽  
Muscle Groups ◽  
Total Muscle

Muscle distribution was studied in 109 Duroc × Yorkshire, Hampshire × Yorkshire and Yorkshire × Yorkshire barrows and gilts fed either high or low energy rations (3652 and 2757 kcal DE/kg, containing 19.9% and 15.3% protein, respectively) and slaughtered at 23, 68, 91 or 114 kg liveweight. Individually dissected muscles from half carcasses were grouped into nine "standard muscle groups" and expressed as percentages of total side muscle. Slight changes occurred in muscle distribution between 23 and 68 kg liveweight, but remained quite constant thereafter. Breed groups were quite similar except that Duroc × Yorkshire pigs had a significantly greater percentage of muscle in the spinal group. The influence of sex appeared to vary relative to liveweight, with gilts maturing at earlier weights than barrows. Ration influence was negligible except for the distal thoracic limb group, which had a slightly greater percentage of muscle in pigs on the HE ration than the LE ration. Unexplained interactions between sex and ration and sex and breed effects occurred for the thorax to thoracic limb muscle group. Comparisons of the present pig data with those from cattle indicated that, in pigs, diphasic growth patterns may not be as pronounced as in cattle, and that individual muscles may be growing proportionate to total muscle very early in life. There seemed to be little evidence to indicate that selection pressures have had any influence on changing the muscle distribution in swine.

INVESTIGATION ON A DEVELOPED WEARABLE ASSISTIVE DEVICE (WAD) IN REDUCTION LUMBAR MUSCLES ACTIVITY

2013 ◽  
Vol 25 (03) ◽  
pp. 1350035 ◽  
Author(s):  
Hadi Heydari ◽  
Maryam Hoviattalab ◽  
Mahmood Reza Azghani ◽  
Masoud Ramezanzadehkoldeh ◽  
Mohamad Parnianpour
Keyword(s):  
Lumbar Spine ◽  
Biomechanical Model ◽  
Erector Spinae ◽  
Assistive Device ◽  
Trunk Flexion ◽  
Biomechanical Models ◽  
Extensor Muscles ◽  
The Right ◽  
Internal Oblique ◽  
Good Agreement

A new wearable assistive device (WAD) was developed to decrease required force on the lumbar spine in static holding tasks. In order to obtain moments on lumbar spine in two conditions, with and without WAD, a biomechanical static model was used for estimation of external moments on lumbar spine. The results of biomechanical models indicated that there was a reduction in the lumbar moment ranging from 20% to 43% using WAD depending on the load and flexion angle. A total of 15 male healthy subjects were tested to experimentally verify the predicted reduction of external moments on the spine by wearing WAD. Normalized electromyography (EMG) of the right and left lumbar and thoracic erector spinae (LES, TES), latissimus dorsi (LD), external oblique (EO), internal oblique (IO) and rectus abdominus (RA) muscles were monitored at three lumbar flexion positions (0°, 30° and 60°) in symmetric posture with three different loads (0, 5 and 15 kg) in two conditions of with and without WAD. The effects of WAD and load were significant for all muscles but the interaction effects were only significant for extensor muscles groups (p < 0.016). Results of statistical analysis (ANOVA) on the normalized EMG while wearing WAD indicated that the muscle activity of right and left LES, TES and LD muscles significantly decreased (p < 0.001). This reduction for right LES, TES, LD muscles at 15 kg load and 60° trunk flexion were 23.2%, 30% and 27.8%, respectively which were in good agreement with the biomechanical model results.

Co-Contraction Recruitment and Spinal Load during Isometric Pushing Tasks

2005 ◽  
Vol 49 (14) ◽  
pp. 1330-1333 ◽  
Author(s):  
Kevin Granata ◽  
Patrick Lee ◽  
Tim Franklin
Keyword(s):  
Biomechanical Model ◽  
Neuromuscular Control ◽  
Surface Emg ◽  
Trunk Flexion ◽  
Materials Handling ◽  
Manual Materials Handling ◽  
Muscle Groups ◽  
Spinal Load ◽  
Theoretical Analyses ◽  
Flexion And Extension

Pushing and pulling tasks account for 20% of occupational low-back injury claims but few studies have investigated the neuromuscular control of the spine during these tasks. Primary torso muscle groups recruited during pushing tasks include the rectus abdominis and external obliques. However, theoretical analyses suggest that co-contraction of the paraspinal muscles is necessary to stabilize the spine during flexion exertions. A biomechanical model was implemented to estimate co-contraction and spinal load from measured surface EMG and trunk moment data recorded during trunk flexion and extension exertions. Results demonstrate that co-contraction during flexion exertions was approximately twice the value of co-contraction during extension. Co-contraction accounted for up to 47% of the total spinal load during flexion exertions and spinal load attributed to co-contraction was nearly 50% greater during flexion than during extension exertions despite similar levels of trunk moment. Results underscore the need to consider neuromuscular recruitment when evaluating biomechanical risks. Keywords: Spine; Co-contraction; Push; Manual Materials Handling; Biomechanics

scholarly journals MAppleT: simulation of apple tree development using mixed stochastic and biomechanical models

2008 ◽  
Vol 35 (10) ◽  
pp. 936 ◽  
Author(s):  
Evelyne Costes ◽  
Colin Smith ◽  
Michael Renton ◽  
Yann Guédon ◽  
Przemyslaw Prusinkiewicz ◽  
...  
Keyword(s):  
Apple Tree ◽  
Mechanistic Model ◽  
Biomechanical Model ◽  
Stem Form ◽  
Basal Diameter ◽  
Tree Form ◽  
Biomechanical Models ◽  
Capture Event ◽  
Hierarchical Hidden Markov Model ◽  
Event Dynamics

Construction of tree architectural databases over years is time consuming and cannot easily capture event dynamics, especially when both tree topology and geometry are considered. The present project aimed to bring together models of topology and geometry in a single simulation such that the architecture of an apple tree may emerge from process interactions. This integration was performed using L-systems. A mixed approach was developed based on stochastic models to simulate plant topology and mechanistic model for the geometry. The succession of growth units (GUs) along axes and their branching structure were jointly modelled by a hierarchical hidden Markov model. A biomechanical model, derived from previous studies, was used to calculate stem form at the metamer scale, taking into account the intra-year dynamics of primary, secondary and fruit growth. Outputs consist of 3-D mock-ups – geometric models representing the progression of tree form over time. To asses these models, a sensitivity analysis was performed and descriptors were compared between simulated and digitised trees, including the total number of GUs in the entire tree, descriptors of shoot geometry (basal diameter, length), and descriptors of axis geometry (inclination, curvature). In conclusion, despite some limitations, MAppleT constitutes a useful tool for simulating development of apple trees in interaction with gravity.

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