scholarly journals Low effective mechanical advantage of giraffes’ limbs during walking reveals trade-off between limb length and locomotor performance

2021 ◽  
Author(s):  
Christopher Basu ◽  
John R. Hutchinson
Keyword(s):  
Body Mass ◽  
Inverse Dynamics ◽  
Limb Length ◽  
Segment Length ◽  
Mechanical Advantage ◽  
Walking Gait ◽  
Moment Arms ◽  
Athletic Ability ◽  
Close Relatives ◽  
Similar Body

AbstractGiraffes (Giraffa camelopardalis) possess specialised locomotor morphology, namely elongate and gracile distal limbs. Whilst this contributes to their overall height (and enhanced feeding behaviour), we propose that the combination of long limb segments and modest muscle lever arms results in low effective mechanical advantage (EMA, the ratio of in-lever to out-lever moment arms), when compared with other cursorial mammals. To test this, we used a combination of experimentally measured kinematics and ground rection forces (GRFs), musculoskeletal modelling, and inverse dynamics to calculate giraffe forelimb EMA during walking. Giraffes walk with an EMA of 0.34 (±0.05 S.D.), with no evident association with speed within their walking gait. Giraffe EMA was markedly below the expectations extrapolated from other mammals ranging from 0.03 – 297 kg, and provides further evidence that EMA plateaus or even diminishes in mammals exceeding horse size. We further tested the idea that limb segment length is a factor which determines EMA, by modelling the GRF and muscle moment arms in the extinct giraffid Sivatherium giganteum and the other extant giraffid Okapia johnstoni. Giraffa and Okapia shared similar EMA, despite a 4-6 fold difference in body mass (Okapia EMA = 0.38). In contrast Sivatherium, sharing a similar body mass to Giraffa, had greater EMA (0.59), which we propose reflects behavioural differences, such athletic performance. Our modelling approach suggests that limb length is a determinant of GRF moment arm magnitude, and that unless muscle moment arms scale isometrically with limb length, tall mammals are prone to low EMA.Significance StatementGiraffes are the tallest living animals - using their height to access food unavailable to their competitors. It is not clear how their specialized anatomy impacts their athletic ability. We made musculoskeletal models of the forelimbs from a giraffe and two close relatives, and used motion-capture and forceplate data to measure how efficient they are when walking in a straight line. A horse for example, uses just 1 unit of muscle force to oppose 1 unit of force on the ground. Giraffe limbs however are comparatively disadvantaged – their muscles must develop 3 units of force to oppose 1 unit of force at the ground. This explains why giraffes walk and run at relatively slow speeds.

Adaptive and phylogenetic influences on musculoskeletal design in cercopithecine primates

2002 ◽  
Vol 205 (21) ◽  
pp. 3399-3412 ◽  
Author(s):  
J. D. Polk
Keyword(s):  
Body Mass ◽  
Three Dimensional ◽  
Bending Moments ◽  
Joint Moments ◽  
Entire Sample ◽  
Mechanical Advantage ◽  
Similar Body ◽  
Walking Speeds ◽  
Locomotor Adaptations ◽  
Limb Proportions

SUMMARY Broad allometric studies of the musculoskeletal system have frequently sought to explain how locomotor variables have been influenced by body mass. To examine animals that vary widely in body mass, these studies have included taxa that differ in their locomotor adaptations and phylogenetic relatedness. Because these sources of diversity could obscure the effects of body mass,this study was designed to test the effects of adaptive differences in limb proportions and phylogeny, as well as body mass, on locomotor kinematics and extensor muscle mechanical advantage. More specifically, two hypotheses were tested in a sample of closely related animals: (i) that, among animals with similar body mass, those with longer limb segments should adopt more extended limb postures to moderate the joint and midshaft bending moments that they experience, and (ii) that body mass will have similar influences on joint posture and joint moments in closely related and diverse mammalian samples. Three-dimensional kinematic and synchronous force-platform data were collected for six individual cercopithecine monkeys ranging in mass from 4kg to 24kg and at a range of walking speeds. Comparisons among three monkeys with similar body mass but different limb segment lengths reveal a significant effect of limb proportion on posture. That is, animals with longer limbs frequently use more extended limb postures and can have correspondingly lower joint moments. The scaling of locomotor variables across the entire sample of closely related monkeys was generally similar to published results for a diverse sample of mammals, with larger monkeys having more extended limb postures, lower joint moments and greater effective mechanical advantage (EMA) for their limb extensor musculature. Ankle EMA, however, did not increase with body mass in the primate sample, suggesting that clade-specific adaptive differences (e.g. the use of arboreal supports by primates) may constrain the effects of body mass.

scholarly journals Morphological determinants of jumping performance in the Iberian green frog

2019 ◽  
Vol 66 (4) ◽  
pp. 417-424
Author(s):  
Gregorio Moreno-Rueda ◽  
Abelardo Requena-Blanco ◽  
Francisco J Zamora-Camacho ◽  
Mar Comas ◽  
Guillem Pascual
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Fluctuating Asymmetry ◽  
Hind Limb ◽  
Limb Length ◽  
Age Classes ◽  
Jumping Performance ◽  
Hind Limbs ◽  
Selective Forces ◽  
Pelophylax Perezi

Abstract Predation is one of the main selective forces in nature, frequently selecting potential prey for developing escape strategies. Escape ability is typically influenced by several morphological parameters, such as morphology of the locomotor appendices, muscular capacity, body mass, or fluctuating asymmetry, and may differ between sexes and age classes. In this study, we tested the relationship among these variables and jumping performance in 712 Iberian green frogs Pelophylax perezi from an urban population. The results suggest that the main determinant of jumping capacity was body size (explaining 48% of variance). Larger frogs jumped farther, but jumping performance reached an asymptote for the largest frogs. Once controlled by structural body size, the heaviest frogs jumped shorter distances, suggesting a trade-off between fat storage and jumping performance. Relative hind limb length also determined a small but significant percentage of variance (2.4%) in jumping performance—that is, the longer the hind limbs, the greater the jumping capacity. Juveniles had relatively shorter and less muscular hind limbs than adults (for a given body size), and their jumping performance was poorer. In our study population, the hind limbs of the frogs were very symmetrical, and we found no effect of fluctuating asymmetry on jumping performance. Therefore, our study provides evidence that jumping performance in frogs is not only affected by body size, but also by body mass and hind limb length, and differ between age classes.

Hyperparathyroidism and Vitamin D Deficiency after Laparoscopic Gastric Bypass

2008 ◽  
Vol 74 (6) ◽  
pp. 469-475 ◽  
Author(s):  
Ronald H. Clements ◽  
Kishore Yellumahanthi ◽  
Mary Wesley ◽  
Naveen Ballem ◽  
Kirby I. Bland
Keyword(s):  
Body Mass Index ◽  
Vitamin D ◽  
Gastric Bypass ◽  
Racial Differences ◽  
Body Mass ◽  
Laparoscopic Gastric Bypass ◽  
Serum Vitamin ◽  
Inverse Correlation ◽  
Limb Length ◽  
Roux Limb

Hyperparathyroidism (HPT) can occur after gastric bypass because of the alteration in vitamin D and calcium absorption. Adequate serum vitamin D concentrations have not been clearly defined in this patient population. Vitamin D (Vit D) and parathyroid hormone (PTH) were assessed 1 year after laparoscopic gastric bypass (LGB). The prevalence of HPT and Vit D deficiency were determined and their association was evaluated using Fisher's exact test. Ninety-three patients (aged 44 ± 1.1 years, 49.6 ± 0.67 kg/m2 body mass index, 79.6% female, 69.6% white) were evaluated. The prevalence of Vit D deficiency (less than 20 ng/mL) and HPT (greater than 65 pg/mL) was 23.6 per cent (n = 22) and 25.7 per cent (n = 28), respectively. Among patients with HPT, only eight of 28 (28.6%) had Vit D deficiency, and of those with Vit D deficiency, only eight of 22 (36.4%) had HPT. There was a weak inverse correlation (r = –0.37) between PTH and Vit D. Blacks are at higher risk for Vit D deficiency. There was no significant association between Vit D deficiency and HPT, Vit D deficiency and Roux limb length, or HPT and Roux limb length. After LGB, Vit D deficiency and hyperparathyroidism occur commonly. Body mass index and Roux limb length are not associated with these two conditions, but racial differences do exist. There is a weak inverse correlation between Vit D and PTH. Further research is needed to elucidate the causes, treatments, and significance of HPT after LGB.

scholarly journals Shear Wave Predictions of Achilles Tendon Loading during Human Walking

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Emily M. Keuler ◽  
Isaac F. Loegering ◽  
Jack A. Martin ◽  
Joshua D. Roth ◽  
Darryl G. Thelen
Keyword(s):  
Achilles Tendon ◽  
Shear Wave ◽  
Wave Speed ◽  
Inverse Dynamics ◽  
Human Walking ◽  
Cross Sectional ◽  
Moment Arms ◽  
Subject Specific ◽  
S Peak

Abstract The evaluation of in vivo muscle-tendon loads is fundamental to understanding the actuation of normal and pathological human walking. However, conventional techniques for measuring muscle-tendon loads in the human body are too invasive for use in gait analysis. Here, we demonstrate the use of noninvasive measures of shear wave propagation as a proxy for Achilles tendon loading during walking. Twelve healthy young adults performed isometric ankle plantarflexion on a dynamometer. Achilles tendon wave speed, tendon moment arms, tendon cross-sectional area and ankle torque were measured. We first showed that the linear relationship between tendon stress and wave speed squared can be calibrated from isometric tasks. There was no significant effect of knee angle, ankle angle or loading rate on the subject-specific calibrations. Calibrated shear wave tensiometers were used to estimate Achilles tendon loading when walking at speeds ranging from 1 to 2 m/s. Peak tendon stresses during pushoff increased from 41 to 48 MPa as walking speed was increased, and were comparable to estimates from inverse dynamics. The tensiometers also detected Achilles tendon loading of 4 to 7 MPa in late swing. Late swing tendon loading was not discernible in the inverse dynamics estimates, but did coincide with passive stretch of the gastrocnemius muscle-tendon units. This study demonstrates the capacity to use calibrated shear wave tensiometers to evaluate tendon loading in locomotor tasks. Such technology could prove beneficial for identifying the muscle actions that underlie subject-specific movement patterns.

scholarly journals Development and validation of anthropometric prediction equations for estimation of lean body mass and appendicular lean soft tissue in Indian men and women

2013 ◽  
Vol 115 (8) ◽  
pp. 1156-1162 ◽  
Author(s):  
Bharati Kulkarni ◽  
Hannah Kuper ◽  
Amy Taylor ◽  
Jonathan C. Wells ◽  
K. V. Radhakrishna ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Lean Body Mass ◽  
Body Mass ◽  
Prediction Models ◽  
Reference Method ◽  
Epidemiological Studies ◽  
Prediction Equations ◽  
Men And Women ◽  
Wide Range ◽  
Similar Body

Lean body mass (LBM) and muscle mass remain difficult to quantify in large epidemiological studies due to the unavailability of inexpensive methods. We therefore developed anthropometric prediction equations to estimate the LBM and appendicular lean soft tissue (ALST) using dual-energy X-ray absorptiometry (DXA) as a reference method. Healthy volunteers ( n = 2,220; 36% women; age 18-79 yr), representing a wide range of body mass index (14–44 kg/m2), participated in this study. Their LBM, including ALST, was assessed by DXA along with anthropometric measurements. The sample was divided into prediction (60%) and validation (40%) sets. In the prediction set, a number of prediction models were constructed using DXA-measured LBM and ALST estimates as dependent variables and a combination of anthropometric indices as independent variables. These equations were cross-validated in the validation set. Simple equations using age, height, and weight explained >90% variation in the LBM and ALST in both men and women. Additional variables (hip and limb circumferences and sum of skinfold thicknesses) increased the explained variation by 5–8% in the fully adjusted models predicting LBM and ALST. More complex equations using all of the above anthropometric variables could predict the DXA-measured LBM and ALST accurately, as indicated by low standard error of the estimate (LBM: 1.47 kg and 1.63 kg for men and women, respectively), as well as good agreement by Bland-Altman analyses (Bland JM, Altman D. Lancet 1: 307–310, 1986). These equations could be a valuable tool in large epidemiological studies assessing these body compartments in Indians and other population groups with similar body composition.

scholarly journals Muscle mechanical advantage of human walking and running: implications for energy cost

2004 ◽  
Vol 97 (6) ◽  
pp. 2266-2274 ◽  
Author(s):  
Andrew A. Biewener ◽  
Claire T. Farley ◽  
Thomas J. Roberts ◽  
Marco Temaner
Keyword(s):  
Ground Reaction Force ◽  
Energy Demand ◽  
Muscle Force ◽  
Inverse Dynamics ◽  
Reaction Force ◽  
Knee Extensor ◽  
Metabolic Cost ◽  
Fold Increase ◽  
Cost Of Transport ◽  
Mechanical Advantage

Muscular forces generated during locomotion depend on an animal's speed, gait, and size and underlie the energy demand to power locomotion. Changes in limb posture affect muscle forces by altering the mechanical advantage of the ground reaction force ( R) and therefore the effective mechanical advantage (EMA = r/ R, where r is the muscle mechanical advantage) for muscle force production. We used inverse dynamics based on force plate and kinematic recordings of humans as they walked and ran at steady speeds to examine how changes in muscle EMA affect muscle force-generating requirements at these gaits. We found a 68% decrease in knee extensor EMA when humans changed gait from a walk to a run compared with an 18% increase in hip extensor EMA and a 23% increase in ankle extensor EMA. Whereas the knee joint was extended (154–176°) during much of the support phase of walking, its flexed position (134–164°) during running resulted in a 5.2-fold increase in quadriceps impulse (time-integrated force during stance) needed to support body weight on the ground. This increase was associated with a 4.9-fold increase in the ground reaction force moment about the knee. In contrast, extensor impulse decreased 37% ( P < 0.05) at the hip and did not change at the ankle when subjects switched from a walk to a run. We conclude that the decrease in limb mechanical advantage (mean limb extensor EMA) and increase in knee extensor impulse during running likely contribute to the higher metabolic cost of transport in running than in walking. The low mechanical advantage in running humans may also explain previous observations of a greater metabolic cost of transport for running humans compared with trotting and galloping quadrupeds of similar size.

scholarly journals Correlation between Balance and BMI in Collegiate students: A cross sectional study

2021 ◽  
Vol 9 (1) ◽  
pp. 3759-3764
Author(s):  
Tejaswini Padmanabha Suvarna ◽  
◽  
Joseph Oliver Raj ◽  
Nithin Prakash ◽  
◽  
...  
Keyword(s):  
Body Mass ◽  
Dynamic Balance ◽  
Cross Sectional Study ◽  
Limb Length ◽  
Static Balance ◽  
Lateral Instability ◽  
Balance Test ◽  
Cross Sectional ◽  
Balance Deficits ◽  
Test Result

Background: Balance deficits are usually related to medial-lateral instability. BMI could be an important factor to consider as; excess body mass or increased accumulation of adipose tissue can directly impact the postural stability which in return impacts balance. Purpose of the study: To find the correlation between BMI and Balance. Method: Sample consisted of 149 students, out of which 100 (67%) were males and 49 (33%) were females. BMI was calculated and was categorized into groups. Bilateral limb length was measured for normalising the data. Static balance was measured by performing blinded stork test and dynamic balance by performing Y- balance test. Data was analysed using Pearson’s correlation test. Result: There was significant correlation between BMI and static balance of left leg (r=0.713, 95% CI 0.623, 0.784, p=0.01) but on comparison, there was no significant correlation between BMI and static balance of right leg (r=0.0458, 95% CI -0.11, -0.205, p=0.58). It was found that there was no significant correlation between BMI and Left Anterior (r= -0.134, 95% CI -0.289, -0.0274, p= 0.103), Left Posterolateral (r=-0.0775, 95% CI -0.235, 0.0843, p=0.347), Left Posteromedial (r=-0.0903, 95% CI -0.248, -0.0715, p=0.273) respectively. Also, it was found that there was no significant correlation between BMI and Right Anterior (r=-0.236, 95% CI -0.382, -0.0778, p=0.00381), Right Posterolateral (r=-0.193, 95% CI -0.343,-0.0334, p=0.0183), Right Posteromedial (r=-0.126, 95% CI -0.281, -0.0354, p=0.125) respectively. Conclusion: There was significant correlation between BMI and static balance of left leg and no correlation was established between BMI and static balance on right leg and also no correlation was established between BMI and static and dynamic balance for right and left leg. KEY WORDS: Static balance, Dynamic balance, Body Mass Index, Obesity, Limb length.

scholarly journals A Fair and EMG-validated Comparison of Recruitment Criteria, Musculotendon Models and Muscle Coordination Strategies, for the Inverse-dynamics Based Optimization of Muscle Forces During Gait

2020 ◽  
Author(s):  
Florian MICHAUD ◽  
Mario Lamas ◽  
Urbano Lugrís ◽  
Javier Cuadrado
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Cost Function ◽  
Inverse Dynamics ◽  
Experimental Studies ◽  
Motor Task ◽  
Muscle Coordination ◽  
Actuator Dynamics ◽  
Moment Arms ◽  
The Central Nervous System

Abstract Experimental studies and EMG collections suggest that a specific strategy of muscle coordination is chosen by the central nervous system to perform a given motor task. A popular mathematical approach for solving the muscle recruitment problem is optimization. Optimization-based methods minimize or maximize some criterion (objective function or cost function) which reflects the mechanism used by the central nervous system to recruit muscles for the movement considered. The proper cost function is not known a priori, so the adequacy of the chosen function must be validated according to the obtained results. In addition of the many criteria proposed, several physiological representations of the musculotendon actuator dynamics along with different musculoskeletal models can be found in the literature, which hinders the selection of the best neuromusculotendon model for each application. Seeking to provide a fair base for comparison, this study measures the efficiency and accuracy of: i) four different criteria; ii) one static and three physiological representations of the musculotendon actuator dynamics; iii) a synergy-based method; all of them within the framework of inverse-dynamics based optimization. Motion/force/EMG gait analyses were performed on ten healthy subjects. A musculoskeletal model of the right leg actuated by 43 Hill-type muscles was scaled to each subject and used to calculate joint moments, musculotendon kinematics and moment arms. Muscle activations were then estimated using the different approaches, and these estimates were compared with EMG measurements. Although similar results were obtained with all the methods, it must be pointed out that a higher complexity of the method does not guarantee better results, as the best correlations with experimental values were obtained with two simplified approaches.

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