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Peak Force (peak + force)
Selected AbstractsObjective and subjective hardness of a test item used for evaluating food mixing abilityJOURNAL OF ORAL REHABILITATION, Issue 3 2007N. M. SALLEH Summary, The aim of this study was to compare objective and subjective hardness of selected common foods with a wax cube used as a test item in a mixing ability test. Objective hardness was determined for 11 foods (cream cheese, boiled fish paste, boiled beef, apple, raw carrot, peanut, soft/hard rice cracker, jelly, plain chocolate and chewing gum) and the wax cube. Peak force (N) to compress each item was obtained from force,time curves generated with the Tensipresser. Perceived hardness ratings of each item were made by 30 dentate subjects (mean age 26·9 years) using a visual analogue scale (100 mm). These subjective assessments were given twice with a 1 week interval. High intraclass correlation coefficients (ICCs) for test,retest reliability were seen for all foods (ICC > 0·68; P < 0·001). One-way anova found a significant effect of food type on both the objective hardness score and the subjective hardness rating (P < 0·001). The wax cube showed significant lower objective hardness score (32·6 N) and subjective hardness rating (47·7) than peanut (45·3 N, 63·5) and raw carrot (82·5 N, 78·4) [P < 0·05; Ryan,Einot,Gabriel,Welsch (REGW)-F]. A significant semilogarithmic relationship was found between the logarithm of objective hardness scores and subjective hardness ratings across twelve test items (r = 0·90; P < 0·001). These results suggest the wax cube has a softer texture compared with test foods traditionally used for masticatory performance test, such as peanut and raw carrot. The hardness of the wax cube could be modified to simulate a range of test foods by changing mixture ratio of soft and hard paraffin wax. [source] Aged mice have enhanced endocortical response and normal periosteal response compared with young-adult mice following 1 week of axial tibial compressionJOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2010Michael D Brodt Abstract With aging, the skeleton may lose its ability to respond to positive mechanical stimuli. We hypothesized that aged mice are less responsive to loading than young-adult mice. We subjected aged (22 months) and young-adult (7 months) BALB/c male mice to daily bouts of axial tibial compression for 1 week and evaluated cortical and trabecular responses using micro,computed tomography (µCT) and dynamic histomorphometry. The right legs of 95 mice were loaded for 60 rest-inserted cycles per day to 8, 10, or 12,N peak force (generating mid-diaphyseal strains of 900 to 1900 µ, endocortically and 1400 to 3100 µ, periosteally). At the mid-diaphysis, mice from both age groups showed a strong anabolic response on the endocortex (Ec) and periosteum (Ps) [Ec.MS/BS and Ps. MS/BS: loaded (right) versus control (left), p,<,.05]. Generally, bone formation increased with increasing peak force. At the endocortical surface, contrary to our hypothesis, aged mice had a significantly greater response to loading than young-adult mice (Ec.MS/BS and Ec.BFR/BS: 22 months versus 7 months, p,<,.001). Responses at the periosteal surface did not differ between age groups (p,>,.05). The loading-induced increase in bone formation resulted in increased cortical area in both age groups (loaded versus control, p,<,.05). In contrast to the strong cortical response, loading only weakly stimulated trabecular bone formation. Serial (in vivo) µCT examinations at the proximal metaphysis revealed that loading caused a loss of trabecular bone in 7-month-old mice, whereas it appeared to prevent bone loss in 22-month-old mice. In summary, 1 week of daily tibial compression stimulated a robust endocortical and periosteal bone-formation response at the mid-diaphysis in both young-adult and aged male BALB/c mice. We conclude that aging does not limit the short-term anabolic response of cortical bone to mechanical stimulation in our animal model. © 2010 American Society for Bone and Mineral Research [source] Motor control of jaw muscles in chewing and in isometric biting with graded narrowing of jaw gapeJOURNAL OF ORAL REHABILITATION, Issue 10 2008P. A. PRÖSCHEL Summary, When a certain bite force is applied during unilateral chewing, the combination of jaw elevator muscle activities is different than when a comparable force is applied in unilateral isometric biting, e.g. on a force transducer. Masticatory peak force is generated in a nearly isometric phase of the chewing cycle, with a jaw gape of about 1 mm. In contrast, peak force in isometric biting on force measuring equipment usually induces jaw gapes of 6 mm or even more. Therefore, we tested the hypothesis that the jaw gape influences relative activation of elevator muscles in unilateral isometric biting. We further examined whether such influence could explain the different activity combinations of chewing and isometric biting. In thirty asymptomatic males, masseter and temporalis activities were recorded during intermittent isometric biting with jaw gapes of 6, 5, 3, 2 and 1 mm and during unilateral chewing. Activity combinations were described by working/balancing ratios and by temporalis/masseter ratios. With decreasing jaw gape the working/balancing ratio of the posterior temporalis decreased (P < 0·002) while that of the masseter increased (P < 0·001). Likewise, the temporalis/masseter ratio on the balancing side increased (P < 0·001). With decreasing jaw gape, activity ratios of isometric biting approached ratios of chewing. We conclude that: (i) relative jaw muscle activation in isometric biting depends on the jaw gape, (ii) relative muscle activation in chewing resembles relative activation of isometric biting with a small ,chewing-like' gape. This suggests that characteristic activity combinations in chewing are mainly a result of the approximately isometric contraction during the slow closing phase of the chewing cycle. [source] Tibio-femoral loading during human gait and stair climbingJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2004William R. Taylor Abstract Surgical intervention of the knee joint routinely endeavors to recreate a physiologically normal joint loading environment. The loading conditions resulting from osteotomies, fracture treatment, ligament replacements, and arthroplasties of the knee are considered to have an impact on the long term clinical outcome; however, knowledge regarding in vivo loading conditions is limited. Using a previously validated musculoskeletal lower limb model, we predicted the tibio-femoral joint contact forces that occur in the human knee during the common daily activities of walking and stair climbing. The average resultant peak force during walking was 3.1 times body weight (BW) across four total hip arthroplasty patients. Inter-individual variations proved larger than the variation of forces for each patient repeating the same task. Forces through the knee were considerably larger during stair climbing than during walking: the average resultant peak force during stair climbing was 5.4 BW although peaks of up to 6.2 BW were calculated for one particular patient. Average anteroposterior peak shear components of 0.6 BW were determined during walking and 1.3 BW during stair climbing. These results confirm both the joint contact forces reported in the literature and the importance of muscular activity in creating high forces across the joint. The magnitudes of these forces, specifically in shear, have implications for all forms of surgical intervention in the knee. The data demonstrate that high contact and shear forces are generated during weight bearing combined with knee flexion angles greater than approximately 15°. Clinically, the conditions that produce these larger contact forces should be avoided during post-operative rehabilitation. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] DEVELOPMENT OF FIBER-ENRICHED BISCUITS FORMULA BY A MIXTURE DESIGNJOURNAL OF TEXTURE STUDIES, Issue 4 2010RAOUDHA ELLOUZE-GHORBEL ABSTRACT The present research studies the optimization of the textural properties of new fiber-enriched biscuit formulae. A mixture design was carried out in order to model the textural properties of dough and biscuit supplemented with Aestivum wheat bran (AWB) and durum wheat bran (DWB). The desirability function was used to determine the coordinates of fiber-enriched biscuit formulae characterized presenting textural properties of dough (hardness, cohesiveness and adhesiveness) and biscuit (maximum peak force) close to those of the commercial product without fiber. Two optimal biscuit formulae (Optimal formula 1 (OM1): 86.66% of wheat flour, 6.67% of DWB and 6.67% of AWB and Optimal formula 2 (OM2): 73.30% of wheat flour, 13.35% of DWB and 13.35% of AWB) were tested at the industrial scale and provided highly acceptable scores from the taste panelists. PRACTICAL APPLICATIONS Consumption of dietary fiber provides health benefits including protection against cardiovascular diseases, cancer and other degenerative diseases. Wheat bran is a readily available and inexpensive source of dietary fiber. In this work, we developed new biscuit formulae enriched with both Aestivum and durum wheat brans. The substitution of wheat flour by wheat brans at their optimum levels led to dietary fiber-enriched biscuits with improved functional and nutritional properties and without undesirable changes in their sensory properties. [source] EVALUATION OF NUMERICAL ALGORITHMS FOR THE INSTRUMENTAL MEASUREMENT OF BOWL-LIFE AND CHANGES IN TEXTURE OVER TIME FOR READY-TO-EAT BREAKFAST CEREALSJOURNAL OF TEXTURE STUDIES, Issue 6 2002C. M. GREGSON ABSTRACT Cornflakes were immersed in milk, rapidly drained and compressed in a TA. XT2i texture analyser (Stable Micro Systems, UK) fitted with an Ottawa Cell. The data were analyzed numerically yielding nine instrumental crispness parameters. Bowl-life was determined using an untrained sensory panel. Three models (Weibull, exponential and modified exponential) successfully modeled the change in mechanical properties as a function of immersion time. An instrumental method of measuring bowl-life is described that measures peak force at a range of immersion times and models the data with the Weibull equation. This method may be a valuable asset to the breakfast cereals industry. [source] Analgesic and anti-inflammatory actions of robenacoxib in acute joint inflammation in dogJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2010V. B. SCHMID Schmid, V. B., Spreng, D. E., Seewald, W., Jung, M., Lees, P., King, J. N. Analgesic and anti-inflammatory actions of robenacoxib in acute joint inflammation in dog. J. vet. Pharmacol. Therap. 33, 118,131. The objectives of this study were to establish dose,response and blood concentration,response relationships for robenacoxib, a novel nonsteroidal anti-inflammatory drug with selectivity for inhibition of the cyclooxygenase (COX)-2 isoenzyme, in a canine model of synovitis. Acute synovitis of the stifle joint was induced by intra-articular injection of sodium urate crystals. Robenacoxib (0.25, 0.5, 1.0, 2.0 and 4.0 mg/kg), placebo and meloxicam (0.2 mg/kg) were administered subcutaneously (s.c.) 3 h after the urate crystals. Pharmacodynamic endpoints included data from forceplate analyses, clinical orthopaedic examinations and time course of inhibition of COX-1 and COX-2 in ex vivo whole blood assays. Blood was collected for pharmacokinetics. Robenacoxib produced dose-related improvement in weight-bearing, pain and swelling as assessed objectively by forceplate analysis (estimated ED50 was 1.23 mg/kg for z peak force) and subjectively by clinical orthopaedic assessments. The analgesic and anti-inflammatory effects of robenacoxib were significantly superior to placebo (0.25,4 mg/kg robenacoxib) and were non-inferior to meloxicam (0.5,4 mg/kg robenacoxib). All dosages of robenacoxib produced significant dose-related inhibition of COX-2 (estimated ED50 was 0.52 mg/kg) but no inhibition of COX-1. At a dosage of 1,2 mg/kg administered s.c., robenacoxib should be at least as effective as 0.2 mg/kg of meloxicam in suppressing acute joint pain and inflammation in dogs. [source] Scaling of plantar pressures in mammalsJOURNAL OF ZOOLOGY, Issue 3 2009F. Michilsens Abstract The interaction of the limbs with the substrate can teach a lot about an animal's gait mechanics. Unlike ground-reaction forces, plantar pressure distributions are rarely studied in animals, but they may provide more detailed information about the loading patterns and locomotor function of specific anatomical structures. With this study, we aim to describe pressures for a large and diverse sample of mammalian species, focusing on scaling effects. We collected dynamic plantar pressure distributions during voluntary walking in 28 mammal species. A dynamic classification of foot use was made, which distinguished between plantiportal, digitiportal and unguliportal animals. Analysis focused on scaling effects of peak pressures, peak forces and foot contact areas. Peak pressure for the complete mammal sample was found to scale to (mass)1/2, higher than predicted assuming geometric similarity, and we found no difference between the different types of foot use. Only the scaling of peak force is dependent on the dynamic foot use. We conclude that plantar peak pressure rises faster with mass than expected, regardless of the type of foot use, and scales higher than in limb bones. These results might explain some anatomical and behavioural adaptations in graviportal animals. [source] Metabolic costs of force generation for constant-frequency and catchlike-inducing electrical stimulation in human tibialis anterior muscleMUSCLE AND NERVE, Issue 3 2002Aivaras Ratkevicius PhD Abstract Metabolic costs of force generation were compared for constant-frequency and catchlike-inducing electrical stimulation. Repetitive catchlike-inducing trains consisted of 2 interpulse intervals (IPIs) at 12.5 ms, 1 IPI at 25 ms, and 5 IPIs at 50 ms. Constant-frequency trains consisted of 8 IPIs at 37.5 ms. One train was delivered to the peroneal nerve every 2.5 s for 36 times under ischemic conditions. Anaerobic adenosine triphosphate (ATP) turnover was determined using 31-phosphorus magnetic resonance spectroscopy (P-MRS) of the human tibialis anterior muscle. Compared with constant-frequency trains, catchlike-inducing trains produced a faster force generation and were more effective in maintaining the force,time integral as well as peak force. However, ATP costs of force generation were similar for the catchlike-inducing and constant-frequency stimulation (6.7 ± 1.1 and 6.6 ± 1.0 ,mol ATP/kg wet weight/N·s, respectively, P = 0.601). This suggests that the positive effects of catchlike-inducing stimulation on force maintenance are mediated by potentiated Ca2+ release from the sarcoplasmic reticulum rather than by lower metabolic costs of muscle force generation. Our findings also suggest that catchlike-inducing stimulation produces larger forces in fatigued muscle than constant-frequency trains and thus may be beneficial for muscle training or rehabilitation when muscle loading needs to be maintained in repetitive contractions. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000,000, 2002 [source] Pes planovalgus in RA: a descriptive and analytical study of foot function determined by gait analysisMUSCULOSKELETAL CARE, Issue 1 2003Deborah E. Turner BSc SRCh Abstract Objective: To compare gait and foot function between rheumatoid arthritis (RA) patients with painful pes planovalgus deformity and healthy age- and sex-matched adults. Methods: Gait analysis was undertaken in 23 RA patients (14 female and 9 male, mean age 52.3 years, mean disease duration 6.6 years) and 23 healthy adults (14 female and 9 male, mean age 49.5 years). Gait measurements included temporal and spatial parameters, plantar pressures and three-dimensional (3D) kinematics at the ankle joint complex (AJC). The mean differences between the groups and associated confidence intervals were calculated using the t distribution. Results: RA patients showed longer gait cycle (mean difference 0.15 sec and 0.14 sec for right and left limbs, respectively) and double-limb support times (mean difference 8.3% and 7.9% for right and left limbs, respectively), shorter stride length (mean difference ,0.31 m for right and left limbs), slower walking speed (mean difference ,0.39 m/sec) and lower cadence (mean difference ,16.6 steps/min). In comparison with the normal group, RA patients had greater AJC dorsi/plantarflexion range of motion (ROM) (mean difference 5.7 °) and inversion/eversion ROM (mean difference 2.9 °). The frontal plane position of the AJC was more everted at specific stance periods (mean difference at heel strike ,2.4 ° and at midstance ,4.0°). Furthermore, both the peak eversion (mean difference ,4.1 °) and summated eversion motion as a function of time (mean difference ,313.9 °) were greater in the RA group. The pes planovalgus foot in RA was characterized by increases in peak pressure (mean difference 34.3 kPa), pressure,time integral (mean difference 18.2 kPa.sec), peak force (mean difference 1.7 N), force,time integral (mean difference 0.7 N.sec), contact time (mean difference 9.8% roll over process) and contact area (mean group difference 3.4 cm,2) in the medial midfoot. Further changes in the load pattern in the forefoot were observed in the RA patients, namely increases in the peak pressure (mean difference 96.4 kPa), pressure,time integral (mean difference 58.4 kPa.sec), and contact area (mean difference 1.7 cm,2) in the medial forefoot region and reduction in contact area (mean difference ,3.9 cm,2), peak force (mean difference ,7.2 N) and force,time integral (mean difference ,1.6 N.sec) in the lateral forefoot. Conclusions: Painful pes planovalgus deformity in RA is associated with global changes in gait, and localized structural and functional changes in the foot which can be accurately measured using clinical gait analysis. Copyright © 2003 Whurr Publishers Ltd. [source] Evaluation of tracheal tube introducers in simulated difficult intubation,ANAESTHESIA, Issue 3 2009C. Janakiraman Summary In a randomised cross-over study, 72 anaesthetists attempted to place Pro-Breathe, new Portex, and Frova single-use tracheal tube introducers and an Eschmann multiple-use introducer in the trachea of a manikin set to simulate a grade 3 laryngeal view. Successful placement (proportion, 95% confidence interval) of either the Frova (78%, 67,86%) or the Eschmann introducer (64%, 52,74%) was significantly more likely (p < 0.0001) than with the Pro-Breathe (4%, 1,12%) or the new Portex introducer (13%, 7,22%). The difference between the success rates for the Frova and the Eschmann introducers (p = 0.08) was not significant. A separate experiment revealed that the peak force that could be exerted by the Pro-Breathe, new Portex and Frova single-use introducers were three to six times greater than that which could be exerted by the Eschmann introducer (p < 0.0001). The single-use introducers are more likely to cause tissue trauma during placement, particularly if held close to the tip. [source] Positive inotropic effect of coenzyme Q10, omega-3 fatty acids and propionyl-L-carnitine on papillary muscle force-frequency responses of BIO TO-2 cardiomyopathic Syrian hamstersBIOFACTORS, Issue 1-4 2008Romina Vargiu Abstract The inability of heart muscle to generate ventricular pressure to adequately propel blood through the cardiovascular system is a primary defect associated with congestive heart failure (CHF). Force-frequency relationship (FFR) is one of the main cardiac defects associated with congestive heart failure. Thus FFR is a convenient methodological tool for evaluating the severity of muscle contractile dysfunction and the effectiveness of therapeutic agents. Papillary muscle isolated from BIO TO-2 cardiomyopathic Syrian hamsters (CMSHs), show a depressed FFR and represents an animal model of human idiopathic dilated cardiomyopathy. In the present study we investigated the effect of CoQ10, omega-3 fatty acids, propionyl-L-carnitine (PLC) and a combination of these 3 agents (formulation HS12607) on FFR in 8 month old BIO TO-2 CMSHs. Papillary muscles isolated from the anesthetized animals were placed in an incubation bath and attached to an isometric force transducer. A digital computer with an analog/digital interface allowed control of both muscle developed force and electrical stimulus parameters. Force-frequency response was evaluated, at Lmax, with increasing frequencies: 0.06, 0.12, 0.25, 0.5, 1, 2 and 4 Hz. HS12607-treatment produced a positive inotropic effect resulting in a significant enhancement (p < 0.05) of the peak force at the highest frequencies (1,4 Hz). In the range of frequency of 1,4 Hz also CoQ10 and omega-3 significantly(p < 0.05) attenuated the fractional decline in developed force. The significant improvement (p < 0.05) of the timing parameter peak rate of tension rise (+T') and peak rate of tension fall (,T') indicating a faster rate of muscle contraction and relaxation respectively, found in CoQ10, omega-3 and PLC-treated CMSHs, may be due to the positive effects of these substances on sarcoplasmic reticulum functions. These findings suggest that naturally occurring CoQ10, omega-3 and PLC, particularly when administered together in a coformulation, might be a valid adjuvant to conventional therapy in dilated cardiomyopathy especially when considering that they are natural substances, devoid of side effects. [source] Load force during manual transport in Parkinson's diseaseACTA NEUROLOGICA SCANDINAVICA, Issue 6 2004X. Guo Objectives , To search for a physiological method for the measurement of upper extremity dexterity during activities of daily life in Parkinson's disease (PD). Materials and methods , We examined load force output during manual transport in seven patients with PD and 10 healthy controls. PD patients were measured in both the non-medicated and medicated states. The test movement included two continuous sub-movements: an upward-forward transport of an object from the table to the stand, and a downward-backward transport of the object from the stand to the table. Hand movements were recorded using an optoelectronic camera, and load force was measured using a force sensor installed in the test object. Results , Compared with the controls, PD patients had a different pattern of load force output characterized by slower force development and release, lower peak force, and less dynamic force generation during movement. After medication, the speed of force development and the level of peak force increased in the patients. Conclusions , These findings suggest that PD impairs the production of preprogrammed movements. The movements observed in the PD patients may result from compensatory strategies relying more on feedback mechanisms. [source] Maximal explosive muscle power in obese and non-obese prepubertal childrenCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 3 2009Stefano Lazzer Summary Objective:, The objectives of the present study was to compare the maximal explosive muscle power developed by the lower limbs in obese and non-obese prepubertal children. Design:, Twenty-five obese [mean body mass index (BMI) z -score: 2·4] and 30 non-obese (mean BMI z -score: 0) children aged 8,12 years, participated in this study. Body composition was measured by bioelectrical impedance analysis and the maximal explosive power of the lower limbs was assessed by the Exercise-Ergometer (a sledge dynamometer). Results:, Absolute peak force (Fpeak) was higher in obese than in non-obese children by 18·2% (P<0·001). Peak speed (vpeak) was not significantly different between groups (P = 0·504). Consequently, absolute peak power (W,peak) was higher in obese than in non-obese children (+19·3%, P = 0·021). Considering gender differences, absolute Fpeak and vpeak were higher in boys than in girls by +12·3 and +17·4% (P<0·05), respectively, thus yielding higher absolute W,peak values in boys as compared to girls (+26·1%, P<0·001). Finally, W,peak normalized for fat-free mass (FFM) was not different between obese and non-obese children but higher in boys than in girls (+24·5%, P<0·001). Conclusions:, Power generation capability per unit of FFM was similar between obese and non-obese children but was significantly higher in boys than girls. On the clinical practice it seems important to devote supplementary care to sustain and improve the motor function of obese and non-obese girls. [source] Guideline threshold limit values (TLVs) for discomfort in repetitive assembly workHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 5 2007L. O'Sullivan This study focused on two of the main occupational risk factors associated with work-related musculoskeletal disorders in light repetitive electronic assembly work, namely repetition and force. Present-day evaluation techniques are primarily posture based and show low sensitivity with regard to rating repetition and force. A simulated assembly task was conducted to investigate the interactions of risk factors and the suitability of hand activity level (HAL) and TLV values for electronics assembly work. Subjects completed the assembly task for three levels of repetition and force. For each treatment a subjective rating of discomfort was recorded. Repeated measures ANOVA identified repetition and force as highly significant factors in light electronic assembly work ( p < .001, p < .05, respectively). The task was also rated using HAL and normalized peak forces (NPF). This study questioned the ability of TLVs in rating discomfort and amendments to the TLVs are suggested. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 423,434, 2007. [source] Functional tissue engineering for tendon repair: A multidisciplinary strategy using mesenchymal stem cells, bioscaffolds, and mechanical stimulation,JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2008David L. Butler Abstract Over the past 8 years, our group has been continuously improving tendon repair using a functional tissue engineering (FTE) paradigm. This paradigm was motivated by inconsistent clinical results after tendon repair and reconstruction, and the modest biomechanical improvements we observed after repair of rabbit central patellar tendon defects using mesenchymal stem cell-gel-suture constructs. Although possessing a significantly higher stiffness and failure force than for natural healing, these first generation constructs were quite weak compared to normal tendon. Fundamental to the new FTE paradigm was the need to determine in vivo forces to which the repair tissue might be exposed. We first recorded these force patterns in two normal tendon models and then compared these peak forces to those for repairs of central defects in the rabbit patellar tendon model (PT). Replacing the suture with end-posts in culture and lowering the mesenchymal stem cell (MSC) concentration of these constructs resulted in failure forces greater than peak in vivo forces that were measured for all the studied activities. Augmenting the gel with a type I collagen sponge further increased repair stiffness and maximum force, and resulted in the repair tangent stiffness matching normal stiffness up to peak in vivo forces. Mechanically stimulating these constructs in bioreactors further enhanced repair biomechanics compared to normal. We are now optimizing components of the mechanical signal that is delivered in culture to further improve construct and repair outcome. Our contributions in the area of tendon functional tissue engineering have the potential to create functional load-bearing repairs that will revolutionize surgical reconstruction after tendon and ligament injury. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1,9, 2008 [source] Scaling of plantar pressures in mammalsJOURNAL OF ZOOLOGY, Issue 3 2009F. Michilsens Abstract The interaction of the limbs with the substrate can teach a lot about an animal's gait mechanics. Unlike ground-reaction forces, plantar pressure distributions are rarely studied in animals, but they may provide more detailed information about the loading patterns and locomotor function of specific anatomical structures. With this study, we aim to describe pressures for a large and diverse sample of mammalian species, focusing on scaling effects. We collected dynamic plantar pressure distributions during voluntary walking in 28 mammal species. A dynamic classification of foot use was made, which distinguished between plantiportal, digitiportal and unguliportal animals. Analysis focused on scaling effects of peak pressures, peak forces and foot contact areas. Peak pressure for the complete mammal sample was found to scale to (mass)1/2, higher than predicted assuming geometric similarity, and we found no difference between the different types of foot use. Only the scaling of peak force is dependent on the dynamic foot use. We conclude that plantar peak pressure rises faster with mass than expected, regardless of the type of foot use, and scales higher than in limb bones. These results might explain some anatomical and behavioural adaptations in graviportal animals. [source] Gait dynamics of Cebus apella during quadrupedalism on different substratesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Kristian J. Carlson Abstract Primates are distinguished from many mammals by emphasizing arboreal lifestyles. Primate arboreal adaptations include specializations for enhancing balance and manipulative skills. Compliant gait and diagonal sequence (DS) footfalls are hypothesized mechanisms for improving balance during arboreal quadrupedalism (AQ), while simultaneously permitting vertical peak force reductions sustained by limbs, particularly forelimbs (FLs). Capuchin monkeys (Cebus apella) are arboreally-adapted quadrupeds that use both lateral sequence (LS) and DS footfalls. As tool-users, capuchins experience selective pressures for FL manipulative capabilities, which seemingly conflict with encountering substantial locomotor stresses. We evaluate kinetic and 3-D kinematic data from 172 limb contacts of two adult males on terrestrial and arboreal substrates to address questions about C. apella gait compliancy, kinematics of LS and DS footfalls during quadrupedalism on different substrates, and whether capuchins reduce FL vertical peak forces relative to hind limb (HL) forces more than other primates that use tools or those that do not. Lower vertical peak forces during AQ are consistent with compliant gait, but mixed kinematic results obscure how the reduction occurs. Forearm adduction angle is one consistent kinematic difference between terrestrial and arboreal quadrupedalism, which may implicate frontal plane movements in gait compliancy. Major differences between DS and LS gaits were not observed in kinetic or kinematic comparisons. Capuchins exhibit low FL/HL vertical peak force ratios like several anthropoids, including tool-users (e.g., chimpanzees), and species not considered tool-users in free-ranging conditions (e.g., spider monkeys). Additional selective pressures besides simply tool use appear responsible for the relative reduction in primate forelimb forces. Am J Phys Anthropol, 2010. © 2010 Wiley-Liss, Inc. [source] | |||||||||||||