Abstract：
:This paper addresses the question of whether maximal vertical jump height depends on initial jumping posture. A direct dynamics computer simulation approach was used to avoid subject preference and practice effects. The human body was modeled as four rigid segments connected by ideal hinge joints, with movement constrained to the sagittal plane and driven by three single-joint torque actuators. Maximal height jumps were found for each of 125 different initial postures. For each initial posture, the optimal pattern of joint torque actuator onset times was found using a multidimensional simplex algorithm searching for maximal jump height. The model results revealed that maximal jump height is relatively insensitive to initial posture, but that the pattern of joint torque onset times necessary to effect these optimal heights varies considerably. Model kinematics indicate that the variability in onset times is necessary to allow the body to re-orient itself in different ways during the downward countermovement phase. This variable re-orientation strategy is followed by a more stereotyped upward thrust phase that is similar despite the differences in starting postures. Model center of mass, joint and segmental kinematics show many features found in experimental studies of jumping, despite the exclusive use of single torque actuators. However, a proximal-to-distal sequence of joint coordination was not found, possibly because of the omission of antagonist and bi-articular muscles. The results suggest that similar vertical jump heights should be obtained using a wide range of initial starting positions.
journal_name
J Biomechjournal_title
Journal of biomechanicsauthors
Selbie WS,Caldwell GEdoi
10.1016/0021-9290(96)00030-9subject
Has Abstractpub_date
1996-09-01 00:00:00pages
1137-46issue
9eissn
0021-9290issn
1873-2380pii
0021929096000309journal_volume
29pub_type
杂志文章abstract：:Three recent studies reveal that the unloaded length of a carotid artery increases significantly and rapidly in response to sustained increases in axial extension. Moreover, such lengthening involves an "unprecedented" increase in the rate of turnover of cells and matrix. Although current data are not sufficient for d...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2004.06.017
更新日期：2005-06-01 00:00:00
abstract：:The reliability of joint rotation measurements is an issue of major interest, especially in clinical applications. The effect of instrumental errors and soft tissue artifacts on the variability of human motion measures is well known, but the influence of the representation of joint motion has not yet been studied. The...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2015.12.045
更新日期：2016-02-08 00:00:00
abstract：:In recent years, computational structural analyses have emerged as important tools to investigate the mechanical response of stent placement into arterial walls. Although most coronary stents are expanded by inflating a polymeric balloon, realistic computational balloon models have been introduced only recently. In th...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2008.01.027
更新日期：2008-01-01 00:00:00
abstract：:Hamstring muscle strain injury is one of the most common injuries in sports involving sprinting and kicking. Studies examining hamstring kinematics and activations are rich for sprinting but lacking for kicking. The purpose of this study was to examine kinematics and activations of hamstring muscles in instep and cut-...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2019.109482
更新日期：2020-01-23 00:00:00
abstract：:An experimental setup was developed for statically measuring seven vertical and three horizontal reaction forces on the foot. In the setup, the leg can be simultaneously loaded (1) by a vertical force, (2) by an externally applied axial moment, and (3) by simulated muscle forces. The foot is free to invert under influ...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(89)90080-8
更新日期：1989-01-01 00:00:00
abstract：:Despite numerous reports on isometric force depression, few reports have quantified force depression during active muscle shortening (dynamic force depression). The purpose of this investigation was to determine the influence of shortening history on isometric force following active shortening, force during isokinetic...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2009.10.041
更新日期：2010-03-03 00:00:00
abstract：:An asymptotic analysis of a lubrication problem is presented for a model of articular cartilage and synovial fluid under the squeeze-film condition. This model is based upon the following constitutive assumptions: (1) articular cartilage is a linear porous-permeable biphasic material filled with a linearly viscous flu...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(92)90024-u
更新日期：1992-03-01 00:00:00
abstract：:This study investigated the plantar pressure distribution during gait on wooden surface with different slipperiness in the presence of contaminants. Fifteen Chinese males performed 10 walking trials on a 5-m wooden walkway wearing cloth shoe in four contaminated conditions (dry, sand, water, oil). A pressure insole sy...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2007.11.001
更新日期：2008-01-01 00:00:00
abstract：:The anatomy of the distal femur has a predominant influence on the mechanics of both patello- and tibio-femoral joints. Especially, the morphological degeneration of the trochlear region dramatically affects the overall knee biomechanics and, from a clinical point of view, the staging of such a degeneration is fundame...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2019.07.008
更新日期：2019-09-20 00:00:00
abstract：:Fibroblasts in intact tendons align with stretching direction, but they tend to orient randomly in healing tendons. Therefore, a question arises: Do fibroblast responses to mechanical stretching depend on their orientation? To address this question, human patellar tendon fibroblasts were grown in custom-made silicone ...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2003.09.011
更新日期：2004-04-01 00:00:00
abstract：:Upper extremity musculoskeletal disorders represent an important health issue across all industry sectors; as such, the need exists to develop models of the hand that provide comprehensive biomechanics during occupational tasks. Previous optical motion capture studies used a single marker on the dorsal aspect of finge...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2011.04.003
更新日期：2011-06-03 00:00:00
abstract：:We developed a computational model of lung parenchyma, which is comprised of individual alveolar chamber models. Each alveolus is modeled by a truncated octahedron. Considering the force balance between the elastin and collagen fibers laying on the alveolar membrane and the pressures acting on the membrane, we compute...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2012.11.031
更新日期：2013-01-18 00:00:00
abstract：:The African Spiny Mouse (Acomys spp.) is a unique outbred mammal capable of full, scar-free skin regeneration. In vivo, we have observed rapid reepithelialization and deposition of normal dermis in Acomys after wounding. Acomys skin also has a lower modulus and lower elastic energy storage than normal lab mice, Mus mu...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2018.10.005
更新日期：2018-11-16 00:00:00
abstract：:Energy conservation in swimming is formulated in terms of four functions of the swim speed v: the consumed power K, the mechanical power P used for horizontal propulsion, the remaining expended mechanical power N, and the thermal power loss H. K is well-known (from VO2) and P = FDv, where the drag force FD is not know...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(94)00143-r
更新日期：1995-08-01 00:00:00
abstract：:Tendon elasticity is important for economical locomotion; however it is unknown whether tendon stiffness is appropriate to achieve an optimal efficiency in various muscles. Here we test the hypothesis that the Achilles tendon is of an appropriate stiffness to maximise medial gastrocnemius muscle efficiency during loco...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2006.07.025
更新日期：2007-01-01 00:00:00
abstract：:We studied the mechanical and anatomical anisotropy of the canine diaphragmatic central tendon (CT). Dumb-bell-shaped strips with effective dimensions of 10 x 2 mm (length x width) were cut from different regions of the canine diaphragmatic CT in two different orientations relative to the direction of neighboring musc...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(91)90289-y
更新日期：1991-01-01 00:00:00
abstract：:Subchondral bone undecalcified samples, extracted from bovine femoral heads, are subjected to a direct tensile load. The Young's modulus of each sample is determined from repeated tests within the elastic limit. In a last test, the tensile load is increased up to the specimen failure, determining the ultimate tensile ...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/s0021-9290(00)00074-9
更新日期：2000-09-01 00:00:00
abstract：:How small do pressure transducers need to be in order to faithfully measure the plantar pressure profiles (PPPs) under normal and diabetic feet? In this study, pressures were collected from five diabetic and six non-diabetic subjects using a commercial measurement system with 25 mm2 transducers. Discrete Fourier Trans...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(95)00116-6
更新日期：1996-07-01 00:00:00
abstract：:The purpose of this paper is to investigate the theoretical basis for the pressure-distension behavior of the urinary bladder. A finite strain theory is developed for hollow spherical structures and it is shown that the Treloar model is a good prototype only for rubber balloons. The pressure-extension ratio relationsh...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(83)90055-6
更新日期：1983-01-01 00:00:00
abstract：:Posteroanterior spinal stiffness assessments are common in the evaluating patients with low back pain. The purpose of this study was to determine the effects of mechanical excitation frequency on dynamic lumbar spine stiffness. A computer-controlled voice coil actuator equipped with a load cell and LVDT was used to de...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2005.10.037
更新日期：2007-01-01 00:00:00
abstract：:The clinical relevance of mechanical testing studies of cadaveric human thoracic spines could be enhanced by using follower preload techniques, by including the intact rib cage, and by measuring thoracic intervertebral disc pressures, but studies to date have not incorporated all of these components simultaneously. Th...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2016.02.038
更新日期：2016-05-03 00:00:00
abstract：:Several algorithms have been proposed for determining the centre of rotation of ball joints. These algorithms are used rather to locate the hip joint centre. Few studies have focused on the determination of the glenohumeral joint centre. However, no studies have assessed the accuracy and repeatability of functional me...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2009.09.029
更新日期：2010-01-19 00:00:00
abstract：:Subchondral bone microdamage due to high-impact loading is a key factor leading to post-traumatic knee osteoarthritis. A quantified assessment of the mechanical characteristics of subchondral bone at the tissue-level is essential to study the mechanism of impact-induced microdamage. We combined mechanical impact testi...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2016.05.016
更新日期：2016-07-05 00:00:00
abstract：:In this study, a three-dimensional finite element model was used to investigate the changes in tissue composition and mechanical signals within human lumbar intervertebral disc during the degenerative progression. This model was developed based on the cell-activity coupled mechano-electrochemical mixture theory. The d...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2014.09.004
更新日期：2014-11-28 00:00:00
abstract：:Orthopaedic management of femoral head osteonecrosis is a common clinical problem for which there presently is no good solution. Current animal models are inappropriate to study potential new solutions, since it has been difficult to replicate the natural history of structural collapse seen in the human disorder. Rece...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/s0021-9290(03)00154-4
更新日期：2003-09-01 00:00:00
abstract：:There are many diseases which cause detrimental changes in the trabecular structure of cancellous bone, leading to mechanical failure of the tissue. One approach to understanding the mechanisms of these diseases is to create idealized models that recreate the morphology of the tissue. This paper presents a partial dev...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(93)90057-l
更新日期：1993-08-01 00:00:00
abstract：:The influence of the ductility of bone tissue on whole-bone strength represents a fundamental issue of multi-scale biomechanics. To gain insight, we performed a computational study of 16 human proximal femurs and 12 T9 vertebral bodies, comparing the whole-bone strength for the two hypothetical bounding cases of fully...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2015.02.066
更新日期：2015-05-01 00:00:00
abstract：:The carpometacarpal (CMC) joints of the hand facilitate motion of the metacarpals and are critical for functional tasks, especially tasks involving precision grasping. Despite their importance, only limited data describing metacarpal kinematics exist. In this short communication, we quantified in vivo metacarpal kinem...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2013.05.019
更新日期：2013-08-09 00:00:00
abstract：:To evaluate the efficacy of implanting a tilting disc aortic valve prosthesis in an angulated (wedged) supra-annular position, an in vitro experimental study was performed. The aortic valve prosthesis was mounted in an axi-symmetric valve chamber in a wedged position and incorporated in a mock circulatory system. Meas...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(86)90150-8
更新日期：1986-01-01 00:00:00
abstract：:Risk for injury during a fall depends on the position and velocity of the body segments at the moment of impact. One technique for reducing impact velocity is to absorb energy in the lower extremity muscles during descent, as occurs during squatting or sitting. However, the protective value of this response may depend...
journal_title：Journal of biomechanics
pub_type： 临床试验,杂志文章
doi：10.1016/j.jbiomech.2003.12.015
更新日期：2004-09-01 00:00:00
