Acta of bioengineering and biomechanics最新文献

Purpose: Cutting maneuvers are important actions in multidirectional sports but associated with noncontact anterior cruciate ligament (ACL) injuries. This study aimed to investigate the effect of different foot strike patterns and cutting angles on knee kinematics and kinetics.

Methods: Twenty healthy male team sports athletes performed cuts with maximum speed at three angles (45, 90 and 135°) with different foot strike patterns (rearfoot strike [RFS] and forefoot strike [FFS]). A three-dimensional motion capture system combined with a force plate was used to collect makers trajectory and ground reaction force (GRF). Vertical GRF, and knee joint angles and moments were compared among these cutting tasks.

Results: Regardless of foot strike patterns, increased knee flexion angle, knee valgus moment, and knee internal rotation moment were observed during cutting to sharper angles (p < 0.001). At 90 and 135°, the FFS condition remained in a varus position and showed lower knee flexion moment than the RFS condition ( p ≤ 0.004). However, no significant differences in knee kinematic and kinetic variables were found between foot strike patterns during cutting to 45°.

Conclusions: These findings suggest that sharper cutting angles potentially increase the risk of ACL injury. Compared with the RFS pattern, the FFS pattern induces a slight knee varus angle and a lower knee flexion moment at sharper angles, which might further reduce the load placed on the knee.

Purpose: The aim of this experimental study was to compare the ability of polyurethane cushions of three arbitrary selected thicknesses to minimize vibrations transmitted from the wheelchair to its user.

Methods: Measurements were made during passive motion on five different surfaces often found in public spaces. Two tests were carried out during the measurements. In the first test, the sensor was located directly on the surface of the wheelchair seat. In the second test, a polyurethane cushion was placed on the seat, on which the measuring sensor was then placed.

Results: The study showed that regardless of the surface on which the wheelchair user moves, the threshold defined in the ISO standard for frequencies in the range of 4-40 Hz was exceeded. However, thanks to the use of polyurethane cushions, vibration damping was visible for frequencies ranging from 10 to 40 Hz. The impact of the user's weight on the magnitude of the perceived vibrations was also observed.

Conclusions: Studies show that wheelchair users are exposed to whole body vibration that can negatively affect their health. Cushions made of polyurethane seem to be a promising solution to reduce whole body vibration in the frequency range that is burdensome and harmful to human health.

Purpose: The aim of this work was to i nvestigate the effects of midsole thickness on non-rearfoot strike runners' redistributions of knee and ankle joint negative and positive work.

Methods: Fourteen healthy male runners wore minimalist, traditional and maximalist shoes and ran in a straight line in each shoe in the laboratory at a speed of 15 km/h, with a ±5% difference being allowed. Whole-body kinematics and ground reaction forces were recorded, and the data of eleven non-rearfoot strikers were used for the analysis. Ankle and knee joint negative and positive work was calculated by integrating each joint's torque power. Friedman test was used for statistical comparisons.

Results: Running in minimalist shoes induced significantly greater ankle joint negative and positive work than in other shoes. Running in maximalist shoes induced significantly lower ankle joint positive work and greater knee joint negative work than in other shoes, and significantly greater knee joint positive work than in minimalist shoes.

Conclusions: Our results indicated that nonrearfoot strikers redistributed joint negative and positive work from the knee to the ankle when using minimalist shoes or from the ankle to the knee when using maximalist shoes. It is recommended that future research employs more rigorous study designs, such as randomised controlled trials and longitudinal studies, to provide a more accurate assessment of the effect of these shoes on in.

Purpose: The aim of this study was to compare the effect of vision (i.e., open and closed eyes) on the kinetic and kinematic parameters of the standing back tuck somersault (SBTS) in artistic gymnasts and parkour athletes.

Methods: Eleven male parkour athletes (age 22.53 ± 2.36 years; height 1.72 ± 0.08 m; weight 69.58 ± 3.72 kg) and seven male artistic gymnasts (age 21.96 ± 2.64 years; height 1.62 ± 0.02 m; weight 63.54 ± 1.35 kg) participated in this study. Each subject was asked to perform the SBTS in the same condition (i.e., first open-eyes then closed-eyes). 2D kinetic and kinematic analysis was conducted.

Results: The results showed significant interaction (i.e., vision and sport) obtained at the take-off angle (p <0.05 and d = 1.992), horizontal displacement (p <0.05 and d = 1.906) and technical execution (p < 0.05 and d = 1.972). This interaction indicates that when vision is permitted, artistic gymnasts and parkour athletes were similar in all kinetic and kinematic parameters, and technical execution (p > 0.05). However, the elimination of vision during SBTS only affected parkour athletes (i.e., landing angle, ground reaction force, vertical velocity and technical execution, p < 0.05 and d > 1.20) while artistic gymnasts remain unchanged.

Conclusion: We conclude that the specificity of the practice in each of the two sports disciplines influences the kinetic and kinematic control of the SBTS and suggests that with closed-eyes, the integration of afferent information relating to the vestibular and proprioceptive systems is different and specific to each discipline's goal. Artistic gymnasts seem to be better skilled in the mechanical and technical control of the SBTS than parkour athletes.

Purpose: The aim of the study was to analyze the length and width of the feet and the mutual rate of growth of these features in 3-year-old girls and boys classified into age categories taking into account the semi-annual division.

Methods: The study covered 800 children (400 girls and 400 boys) aged 3. The CQ-ST podoscope was applied as the research tool. The data were analyzed based on Student's t-test for independent samples, Mann-Whitney U-test, Wilcoxon test and simple regression.

Results: There were statistically significant differences in the width of the right and left feet, for both girls (1st group: p<0.001; 2nd group: p = 0.006) and boys (1st group: p<0.001; 2nd group: p<0.001), in the absence of differences in length. In the regression models created for the results of girls and boys classified into age categories, the coefficients of determination ranged from R2= 0.24 to R2= 0.48.

Conclusions: The right and left feet of the examined girls and boys are characterized by symmetry in terms of length, while in terms of width, the left feet are larger than the right ones. In girls, the width of the foot increases proportionally by about 67-69% of the length, while in boys, the increase in foot width is 49-61% of the growth in length. In boys classified to the 2nd group, the growth of the foot in width in relation to its lenght in length is smaller than in the 1st group.

Purpose: The purpose of this study was to model and describe the processes and phenomena occurring during the sliding interaction between biometal rods (titanium alloys Ti6Al4V and Ti6Al7Nb, austenitic steel AISI 316L, alloy CoCrMo) and PE-UHMW cords, used in spine stabilization systems to treat early-onset idiopathic scoliosis.

Methods: The wear of friction joints in two lubricating solutions (acidic sodium lactate and distilled water) at stabilized temperature T = 38 °C was studied. The wear of the polymeric cords was investigated through analyses of the chemical composition of the surface of the cords and microscopic examinations of the changes occurring on this surface. In addition, microscopic examinations and EDS analyses of the wear products filtered out from the lubricating medium were carried out.

Results: Metallic particles were found to be present in both lubricating solutions at each stage of the friction process. The largest amount of metallic particles was recorded after 5000 motion cycles.

Conclusions: The presence of metallic wear products is an evidence of the wear of the harder metal rod due to its friction against the PE-UHMW cord. This means that the use of guided-growth implants poses a risk of inflammations in the peri-implant tissues.

Purpose: The primary aim of the present study was to compare the bileaflet and trileaflet aortic valves' performance during uniform blood flow model and boundary conditions. The secondary aim of the study was to determine the effect of Newtonian/non-Newtonian fluid flow assumption on blood flow directly behind the trileaflet valve.

Methods: The geometrical model of the whole system consist of the left ventricle, fragment of the aorta and mechanical valves. A representation of pulsatile flow was obtained by measuring blood flow velocity (Doppler ultrasound examination). We have assumed turbulent blood flow. We considered two blood models, Newtonian and non-Newtonian (Carreau model). The valves' performance was assessed using the reduced stress in the valves, the shear stress in the aortic wall, flow velocity field and the effective orifice area.

Results: The maximum von Mises stress for the bileaflet valve leaflets was 0.3 MPa and for the trileaflet valve - 0.06 MPa. The maximum flow velocity for the bileaflet valve was 4.52 m/s for 40° and for the trileaflet valve - 5.74 m/s. Higher shear stress was present in the bileaflet (151.5 Pa) than for the trileaflet valve (49.64 Pa).

Conclusions: The results indicate that central blood jet for the trileaflet valve contributes to more physiological blood flow and decreases the risk of haemolysis. The central flow minimises the risk of leaflet dislocation. In addition, lower stresses extend the durability of the valve. However, the trileaflet valve geometry has also disadvantages, for instance, small peripheral streams or relatively low effective orifice area.

Purpose: The symmetry of feet loading and adequate postural control are crucial aspects of proper squat performance. The study aimed to evaluate the effect of various stance widths during squat on postural control and symmetry of feet loading.

Methods: Thirty healthy individuals participated in this study. Each participant performed one type of squat with a narrow stance (NS), hip stance (HS) and wide stance (WS).

Results: A significantly higher value of CoP path length, the velocity of sways and Area95 were obtained for the WS squat compared to NS and HS. In addition, the wide feet setting significantly affected not only the feet loading symmetry but also the strategy (high LyE), the amount of irregularities (high SampEn) and the CoP time-series roughness complexity (high FD). It has been shown that as the base of support grew, the asymmetry index grew.

Conclusions: The wide squat is less stable, requiring more complex postural control behavior and more flexibility. Performing this squat significantly shifts the pressure to the dominant limb.