Search results for "Mechanical Phenomena"
showing 10 items of 532 documents
Walking and Running Require Greater Effort from the Ankle than the Knee Extensor Muscles.
2016
The knee and ankle extensors as human primary antigravity muscle groups are of utmost importance in a wide range of locomotor activities. Yet, we know surprisingly little about how these muscle groups work, and specifically, how close to their maximal capacities they function across different modes and intensity of locomotion. Therefore, to advance our understanding of locomotor constraints, we determined and compared relative operating efforts of the knee and ankle extensors during walking, running, and sprinting.Using an inverse dynamics biomechanical analysis, the muscle forces of the knee and ankle extensors during walking (1.6 m·s), running (4.1 m·s), and sprinting (9.3 m·s) were quant…
Micromechanical Properties and Collagen Composition of Ruptured Human Achilles Tendon
2012
Background:The Achilles tendon is one of the strongest tendons in the human body, and yet it frequently ruptures, which is a substantial clinical problem. However, the cause of ruptures remains elusive.Hypothesis:Ruptured human Achilles tendon displays inferior biomechanical properties and altered collagen composition compared with noninjured tendon.Study Design:Controlled laboratory study.Methods:Biopsy specimens were obtained at the rupture site and the noninjured part of the tendon (internal controls) in 17 patients with acute Achilles tendon rupture. Age- and weight-matched human cadaveric Achilles tendons (external controls) were also obtained. Tendon samples were tested micromechanica…
Movement Variability Increases With Shoulder Pain When Compensatory Strategies of the Upper Body Are Constrained
2017
[DE] This cross-sectional study analyzed the influence of chronic shoulder pain (CSP) on movement variability/kinematics during humeral elevation, with the trunk and elbow motions constrained to avoid compensatory strategies. For this purpose, 37 volunteers with CSP as the injured group (IG) and 58 participants with asymptomatic shoulders as the control group (CG) participated in the study. Maximum humeral elevation (Emax), maximum angular velocity (Velmax), variability of the maximum angle (CVEmax), functional variability (Func_var), and approximate entropy (ApEn) were calculated from the kinematic data. Patients' pain was measured on the visual analogue scale (VAS). Compared with the CG, …
The Retrograde Tibial Nail: presentation and biomechanical evaluation of a new concept in the treatment of distal tibia fractures.
2013
Displaced distal tibia fractures require stable fixation while minimizing secondary damage to the soft tissues by the surgical approach and implants. Antegrade intramedullary nailing has become an alternative to plate osteosynthesis for the treatment of distal metaphyseal fractures over the past two decades. While retrograde intramedullary nailing is a standard procedure in other long bone fractures, only few attempts have been made on retrograde nailing of tibial fractures. The main reasons are difficulties of finding an ideal entry portal and the lack of an ideal implant for retrograde insertion. The Retrograde Tibial Nail (RTN) is a prototype intramedullary implant developed by our group…
Effects of pregnancy on lumbar motion patterns and muscle responses.
2018
The kinematics of the lumbar region and the activation patterns of the erector spinae muscle have been associated with the genesis of low back pain, which is one of the most common complications associated with pregnancy. Despite the high prevalence of pregnancy-related low back pain, the biomechanical adaptations of the lumbar region during pregnancy remain unknown.This study analyzes lumbar spine motion and the activation pattern of the lumbar erector spinae muscle in healthy pregnant women.A case-control study.The study involved 34 nulliparous women (control group) and 34 pregnant women in the third trimester (week 36 ± 1).We recorded the parameters of angular displacement of the lumbar …
Estimation of structural and geometrical properties of cortical bone by computerized tomography in 78-year-old women
2009
The structural and geometrical properties of the tibia shaft were investigated at two sections by means of computerized tomography (CT) in 78-year-old women with high (n = 19) and low (n = 17) calcaneal bone mineral density (BMD, g/cm3) previously measured by 125I-photon absorption. The high BMD group had a 20-21% higher tibial BMD and 9-12% higher bone cross-sectional area than was observed in the low BMD group. The distribution of bone mass indicated that the low BMD group had lost bone mainly from the endosteal surface, especially in the anterior part of the tibia. However, both groups had a similar basic pattern of mass distribution at the measured sections. The high BMD group had highe…
Biomechanical testing of different posterior fusion devices on lumbar spinal range of motion.
2019
Abstract Background Recent minimal-invasive posterior fusion devices are supposed to provide stability and obtain fusion in combination with interbody cages in the instrumented segment. The aim of the present study is to evaluate the primary stability of two minimal-invasive posterior prototypes compared to an established spinous process plate and standard pedicle screw instrumentation. Methods Seven fresh frozen human cadaver lumbar spines (L2–L5) were tested in a spinal testing device with a moment of 7.5 Nm. Spinal stability was determined as mean range of motion (RoM) in the segment L3/L4 during extension-flexion, lateral bending and axial rotation. The RoM was measured during five cond…
Biomechanische Überlegungen über Stoßkräfte und Fußstabilität beim Laufen
1993
The interaction between "man-shoe and surface" is presented as a model to discuss the complexity of human locomotion. Only if the physiological system "man" interacts positively with the physical requirements of shoe and surface quality running will become effective and economical. Especially during the early ground contact phase the hardness of the shoe construction determines the height of the vertical impact load. These adaptations have consequences in the emg amplitudes during the stretch activation phase of the contact. Comparing various jogging shoes with altered construction properties it can be shown that the "hardness" of the shoe material is well adapted by the variation in the em…
Kinematics of Cervical Spine during Rowing Ergometer at Different Stroke Rates in Young Rowers: A Pilot Study
2022
Background: Research on biomechanics in rowing has mostly focused on the lumbar spine. However, injuries can also affect other body segments. Thus, the aim of this pilot study was to explore any potential variations in the kinematics of the cervical spine during two different stroke rates on the rowing ergometer in young rowers. Methods: Twelve young rowers of regional or national level were recruited for the study. The experimental protocol consisted of two separate test sessions (i.e., a sequence of 10 consecutive strokes for each test session) at different stroke rates (i.e., 20 and 30 strokes/min) on an indoor rowing ergometer. Kinematics of the cervical spine was assessed using an iner…
Mechanical activity of small and large intestine in normal and mdx mice: a comparative analysis.
1999
The aim of this study was to compare the motor pattern (recorded as changes in intraluminal pressure) of isolated duodenum and proximal colon between dystrophic mdx and normal mice. When duodenal recordings from control preparations were compared with mdx mice there was no significant difference in the spontaneous motor pattern, responses to electrical nerve stimulation or sensitivity to pharmacological agents. Colonic segments from mdx mice showed a more complex motor pattern, consisting of contractions with amplitude and frequency similar to those of controls and by additional contractions with lower amplitude and higher frequency. Moreover, 70% of the colonic preparations from mdx mice d…