Abstract:Biomechanics is a scientific discipline that deals with force involved in movements, medicine, biology, materials and related disciplines. It is multidisciplinary discipline as well, integrated with many science areas. Its two relevant sub-disciplines, i.e. sports biomechanics and medical biomechanics are highly application-orientated and is an important part of 'Science and Technology of Olympic Games’. This mini-review summarizes the key messages of the scientific work published by the Journal on the research and application of biomechanics in performance sports and sports medicine.

Abstract:To reveal the state of biomechanics in sports medicine and elucidate the direction of development in this field and the questions we are facing. The information of development of biomechanics in different portions of sports medicine was summarized. The main achievements and deficiencies were analysed. The main achievements and deficiencies were summarized, the direction of development in this field were bring forwarded. The biomechanics in sports medicine is developed well, and has a bright future.

Abstract:Objective To observe the effect of rabbit anterior cruciate ligament (ACL) reconstruction with irradiated Achilles tendon allograft, which was added with PDGF-BB、VEGF165 or TGFβ1 genes transduced mesenchymal stem cells(MSCs). Methods Forty male New Zealand white rabbits were divided randomly into five groups with eight animals for each:(1)control group, (2) MSCs group, (3) PDGF-BB transfected MSCs group, (4) VEGF165 transfected MSCs group, (5) TGFβ1 transfected MSCs group. The ACL was replaced with a Achilles tendon allograft. The 2×106 cells with 100 μL fibrin sealant was applied on the Achilles allograft. All animals were sacrificed 12 weeks after ACL reconstruction. Results Histologic findings showed that newly formed vessels and infiltrative fibroblasts were more abundant in VEGF165 group than other guoups. Biomechanical properties of PDGF-BB or TGFα1 groups were significantly better than B control on the max load, the stiffness, the absorbed energy and the maximum tensile strength (P<0.05). The max load, the stiffness and the absorbed energy of MSCs or VEGF165 groups were higher than that of control group,while there were no significant differences (P>0.05). The snap displacement of VEGF165 group was significantly higher than that of control group (P<0.05). The rupture site was all at the body part of the graft, normal ACL and Achilles. Conclusion VEGF165 gene transfected MSCs could significantly promote angiogenesis in the reconstructed ligament, but it did not enhance the mechanical properties of the reconstructed ligament in the rabbit model. Both PDGF-BB gene and TGFβ1 gene transfected MSCs could accelerate the remoedling of the reconstructed ligament.

Abstract:Objective To investigate the osteogenic effect of mechanical stretch on cultured flavum ligament cells derived from thoracic ossification ligament flavum patients. Method Flavum ligament cells were isolated and cultured in vitro. Under mechanical stretch, alkaline phosphatase (ALP) activity in cell layers and the mRNA expressions of osteocalcin (OC) were detected by PNPP method and real-time PCR respectively. Results The ALP activity and the mRNA expressions of osteocalcin were both increased under mechanical stretch. Conclusion These results suggest that mechanical stretch plays important roles in the progression of Thoracic ossification of ligamentum flavum(TOLF) through induction of osteogenic differentiation of TOLF cells.

Abstract:Objective To study the biomechanical characters of male weightlifter’s squat snatch technique. Methods 8 Channel EMG System, 3D force measure system and digital video were adopted to collect sEMG of 8 representative skeletal muscles, plantar force and synchronized video during male weightlifter’s squat snatch in different weights from Shanghai weightlifting team. Results The plantar force curves of weightlifter’s squat snatch in different weights are consistent. The squat snatch technique can be divided into 7 phases based on characteristic curve patterns of plantar force. During squat snatch, the active order of skeletal muscles is M. latissimus dorsi, M. erector spinaeta, M. rectus femoris, M. deltoideus, M. triceps brachii, M. tibialis anterior, M. biceps brachii and M. trapezius. The integrated EMG value of M. trapezius is largest while that of M. latissimus dorsi is smallest. With increasing of barbell weight, the integrated EMG values of M. triceps brachii and M. deltoideus increase to it maximum. Conclusion Attention shall be paid to training weightlifter’s M. trapezius, M. triceps brachii and M. deltoideus during squat snatch in order to improve the weight lifting performance.

Abstract:Objectives the aim of the study is to compare the effects of strength training below maximal load for untrained men with pneumatic variable resistance machine (PST) to the effects of strength training with traditional weight and stack units (TST) on the ratio of hamstring to quadriceps femoris maximal isometric muscle strength. Methods 30 healthy men were attributed into two groups, PST group and TST group; they were required to perform 10 weeks progressive resistance strength training with different strength training apparatus separately. Maximal isometric extension and flexion strength at 120 knee angle were measured before and after the strength training. Results after the strength training, peak isometric torque of knee flexors at 120 knee angle (MVC120-F) and ratio of hamstring to quadriceps femoris maximal isometric torque at 120 knee angle (H/Q-120) increased significantly in PST group with the significant decrease of H/Q-120 in TST group. Significant difference of H/Q-120 was found between two groups. Conclusions training within 40-90%1RM load, PST take advantage of increasing the H/Q-120 than TST while TST takes advantage of increasing muscle speed strength than PST; all results indicate a complementary effect between two types of training methods.

Abstract:Objective (1) To determine the feasibility of using fluid-structure coupled ALE(Arbitrary Lagrangian– Eulerian) method in javelin flight simulation; (2) To determine the attacking angle in the optimum thrust by ALE method. Methods A FEM model of both javelin and air was built by Femb pre-processing software; and materials and elements properties were set up. Based on the applied loads, initial and boundary conditions, the simulation was carried out for given release parameters using LS-DYNSA solver. Results The vertical and horizontal displacement of javelin tip were obtained at 30m/s release speed, 39 degree release angle and 2 meters’ height. Conclusion It is feasible to simulate javelin flight using ALE method; and the adjustment of release parameters in simulation can be controlled easily. The attacking angle is -3°obtained for the optimum throwing distance at 30m/s and 39 degree.

Abstract:Objective To develop a three-dimensional finite element model of human foot for studying stress distribution of the hind foot bones during the jumping moment. Methods CT scanning and CAD/CAM software were used to establish the hind foot bones model. By using plantar pressure of back flop high-jump and calculating the inverse muscle strength, the loads and constraints conditions were simulated. Results Stress distribution of calcaneus、talus and navicular were analyzed during the landing of heel. Stress concentration was found at subtalar joint and dorsal of talus. Conclusion This model can be applied in biomechanical studies of the hind foot bones, especially for providing analytic data to explain the mechanism of jumping-induced injury.

Abstract:Objectives The aims of the study are to evaluate kinematic characteristics of the pole valting in order to enhance the performance level of the athletes. Methods To perform biomechanical analysis on pole-valting techniques of 2 national elite women. During the experiment, the camera is in the fixed point and with the invariable focus and motions are analyzed with the APAS system. Results The loss in rate of B’s horizontal velocity at the moment of take-off in three attemps is 23%,26% and 20%, respectively; while that of As’ are lower, with 16%,23% and 18%, correspondingly. B’s times of three attempts are 0.16 s, 0.16 s and 0.18 s in the phases of long swinging; while that of As’ are correspondingly shorter with 0.12 s, 0.10 s and 0.08 s. Conclusions The kinematic analysis shows that A’s technology is superior to B’s at take-off moment, A’s technology is consistent with the character of "free taking off". The time period of A in the phase of long swing is shorter than B, what suggests adisadvantage to bend the pole, our analysis suggestions that specific strengthening exercise is needed to enhance muscle strength of specific muscle groups and prolong the time period in the phase of long swing.

Abstract:Objective To develop a three-dimensional (3-D) finite element (FE) model of the scoliotic spine. Methods The T6L1 spinal segment of a scoliosis patient was scanned by CT, and CT images were used to generate a geometrical model of the scoliotic spine using Simpleware and Geomagic software. A 3-D FE model was subsequently created and analyzed using ABAQUS. Results The 3-D geometrical model of the scoliotic spine resembled the actual spinal segments. Consisting of 232,315 elements and 356,830 nodes, the FE model could accurately determine vertebral stress and displacement distribution due to a load. Conclusion The 3-D FE model may be used for biomechanical study of scoliosis.

Abstract:Objective The effect of different geometry configurations of abdominal aortic aneurysm on hemodynamics was investigated to supply some information for clinical diagnosis on aneurysm rupture. Methods Different models of the aneurysms were established using its Image data. The flow in the aneurysm was analysed by using the method of computational fluid dynamics under the condition of pulsatile input flow, rigid wall and Newtonian blood flow. The differences of these models were compared. Results The asymmetry model would cause larger value of wall shear stress comparably and have influence on the rupture of aneurysm. The vortexes in the models with excursion of peak value and in the deflected model were changed with different geometry configurations. Conclusion The different geometry configurations of AAA(abdominal aortic aneurysm) would affect the hemodynamics in the aneurysm.

Abstract:Objective To study the properties of artery in different conditions. Method The different simulations of the aorta were made by the linear elastic model with small and large displacement, the nonlinear elastic model and the model with residual stress, respectively. We analyzed the circumference stress distributing and displacement distributing of the above four models by finite element method and made the comparison among them. Results It showed that residual stress changed the distribution of circumference stress but didn’t change the circumference stress level, and have no clear influence on the displacement of the aorta. Conclusion Because of the exist of residual stress, the stress concentration distributing along the blood wall.has obviously decreased.

Abstract:Objective To study the orientated growth of axons in three-dimensional (3D) tissues, and to explore the effects on the rates of advancing, bundling and de-bundling of the axonal growth on an uneven surface of the extracellular matrices (ECM). Methods Based on the experimental observations, it is assumed that the traction for the axonal growth is proportional to the gradient of concentration of the diffusible attractants secreted by the target cells, and the lateral bundling or de-bundling force of the axons is proportional to the gradient of concentration which is the diffusible attractants or repellents secreted by the growth cones. The attractive force points to the uphill direction of the concentration field, the repulsive force points to the downhill direction, and the concentration itself satisfies the diffusion equation. When the growth cones crawl on an uneven surface of the ECM, only the tangential components of the above mentioned forces are helpful for the migration. In this numerical computing, 3D finite difference method and the improved Euler method were employed. Results (1) The basic characteristics of the orientated growth of axons in 3D tissues are similar to those in the 2D medium that were observed by the experiments, it is merely that they are morphologically termed by 2D or 3D problems. (2) The uneven of the ECM does affect the axonal growth. With the slope increasing, the advancing speed of the growth decreases and the lateral speed increases. Conclusions (1) Many mechanisms of the axonal growth revealed by the 2D culture experiments may be still valid in the corresponding 3D cases; (2) The geometry of the ECM is one of the key factors that have impacts on the rate of the axonal growth.

Abstract:Objective To investigate the role of membrane stretch on the pacemaker current in cultured interstitial cells of Cajal. Methods ICC was isolated from murine small intestine and then cultured in the medium with stem cell factors. After 72 hours, ICC was identified by immunohistochemical technique with monoclonal antibody for labeling c-kit protein and the pacemaker current in intestinal ICC were recoded under the conventional whole-cell patch clamp configuration. The membrane stretch was achieved by the application of direct pressure through the patch pipette and perfusion of hypotonic solution. Results At the 72nd hour, 2 to 4 projections were stacked out from the body of ICC, which interconnected with neighboring cells and formed cell networks under light microscope. Immunohistochemistry showed that c-kit protein was positively expressed on the surface of ICC. The spontaneous and rhythmic inward currents (pacemaker currents) were elicited under cells were voltage clamped in the whole-cell patch-clamp configuration and held at -60 mV. The sustained inward current was activated and the amplitudes and frequencies of pacemaker currents increased by the application of membrane stretch. Conclusion The mechanical stretch can regulate basic tone and frequency of gastrointestinal smooth muscle motility via activating or potentiating ICC pacemaker currents.

Abstract:Objective To evaluate osteogenetic effectiveness of hyaluronic acid (HA) mixed with adenovirus mediated human bone morphogenetic protein-2 gene(Adv-hBMP-2) transfected bone marrow derived mesenchymal stem cells (BMSCs) in the repair of radial shaft defects of rabbits. Methods The BMSCs were collected from bone marrow of rabbits, cultured and transfected by Adv-hBMP-2 in vitro. The radial shaft defects (1.5 cm) models in 20 rabbits (40 sides) were created and then injected the cells and/or materials respectively in the following four groups(n=10): Group 1: Adv- hBMP-2 transfected BMSCs+HA; Group 2: Adv-hBMP-2 transfected BMSCs; Gourp 3: HA; Group 4: control.Roentgenography, histological exam￡?biomechanical test and histomorphometrical analysis were studied at various time points. Results The bone defects of 6 out of 8 sides in Adv-hBMP-2+HA Group in the 12th week after injection were repaired completely. At the same time, only 3 sides were repaired completely in Adv-hBMP-2 Group, and none was repaired completely in HA Group and control Group. The X-ray scoring system revealed that the average scores in each groups were 4.63±0.74, 3.38±1.60, 1.63±0.74 and 1.50±0.53, respectively. In the groups of Adv-hBMP-2+HA and Adv- hBMP-2, histological examination revealed that there were much woven callus formation in the sites of the bone defects in the 4-8th week after injection and partial bone marrow cavities were revasculized and lots of osteons were formed in the 12th week after injection; while in HA group and control group, the sites of bone defects were mainly full of fibrous tissue and no complete healing happened. Two ends of the bone defects were hardened. The histomorphometrical analysis showed that the new trabecular bone area in Adv-hBMP-2+HA group and Adv-hBMP-2 group were 16.25±3. 49mm2 and 10.39±2.02mm2, respectively, which has statistically significant difference (P<0.001). The biomechanical test showed that the maximum vertical loading and elastic modulus were (211.54±63.58) N and (113.36±56.47)MPa in Adv- hBMP-2+HA group, and (126.74±53.13 )N and (98.91±63.36)MPa in Adv-hBMP-2 group (P<0.05).The ratios of average maximum vertical loading/normal value of radial shaft in the groups of Adv-hBMP-2+HA and Adv-hBMP-2 were 75.86% and 45.45%, respectively. Conclusion The tissue-engineered bone made by HA mixed with Adv-hBMP-2 transfected BMSCs can repair the bone defects in the radial shaft of rabbits.

Abstract:Objective To explore the bone mineral density, micro-structure and biomechanical changes of the lumbar on rats induced by ovary irradiation. Methods The ovaries of rats were irradiated by 50Gy γ-ray to establish the animal model.The lumbar was got after 90 days. Dual energy X-ray absorpt metry (DEXA ) was used to measure the bone mineral density (BMD). The changes of bone microstructure characters were observed by the scanning electron microscope. Bone biomechanical properties were determined by the maximal loading obtained from the compression test. Results compared with the sham operated group, BMD of the ovary irradiated group was obviously lower(P<0.05), bone microstructure was destructive, and bone biomechanical properties were decreased(P<0.05). Conclusion Osteoporosis of the lumbar was induced by the ovary irradiation on rats.

Abstract:Large conductance, Ca2+-activated K+ channels (BK channels)are widely expressed in various cells and tissues, which have the important physiological functions. Such kind of channels also has many biophysical properties of other members' in potassium ion channels family,, including the ion selectivity, the voltage-dependent gating, the ligand - dependent (calcium-activated) gating and the stress sensitivity. The structural analysis of BK channels can help to learn more about their own gating mechanism and the gating mechanism of other family members as well. Further more, with analyzing the commonness of the whole family members and the specificity of the BK channels, it will be helpful for us to illuminate the structure and the gating mechanism of BK channels.Based on the correlative study of potassium ion channels family, an in-depth discussion about the molecular structure, function and the gating mechanism of BK channels will be given in this paper.