Muscle activity during crouched walking.

OBJECTIVES: Muscle activity during crouched walking has been previously studied in the context of the evolution of hominin bipedalism and human movement disorders. However, crouched walking could also be used in approach hunting where postural height (actual height of the body from the ground to the top of the head during locomotion) is the limiting factor. Here, we aim to analyze the relationship between relative postural height (%stature), kinematics, and muscle activity during crouched walking. MATERIALS AND METHODS: Adult males (n = 19) walked with extended limbs and at three degrees of crouch while their 3D motion capture kinematics and lower limb muscle electromyography were recorded. We measured activation of tibialis anterior, soleus, gastrocnemius medialis, gastrocnemius lateralis, vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus. We analyzed the effects of postural height on kinematics and muscle activation using linear mixed effects model. RESULTS: Flexion angles, individual muscle activation (except for medial gastrocnemius), and total muscle activation were negatively related to relative postural height, that is, were greater at more crouched postures. Relative postural height had a stronger effect on the activation of the thigh and gluteal muscles compared to shank muscles. DISCUSSION: General increase in lower limb muscle activation at lower postural heights suggests a negative relationship between relative postural height and fatigue, and may indicate a possible mechanism by which short stature could benefit the hunter in approach hunting. Greater activation of thigh and gluteal muscles relative to shank muscles may help to identify crouched walking in past human populations.

Pedestrian Safety in Frontal Tram Collision, Part 1: Historical Overview and Experimental-Data-Based Biomechanical Study of Head Clashing in Frontal and Side Impacts.

This article represents the first paper in a two-part series dealing with safety during tram-pedestrian collisions. This research is dedicated to the safety of trams for pedestrians during collisions and is motivated by the increased number of lethal cases. The first part of this paper includes an overview of tram face development from the earliest designs to the current ones in use and, at the same time, provides a synopsis and explanation of the technical context, including a link to current and forthcoming legislation. The historical design development can be characterised by three steps, from an almost vertical front face, to leaned and pointed shapes, to the current inclined low-edged windshield without a protruding coupler. However, since most major manufacturers now export their products worldwide and customisation is only of a technically insignificant nature, our conclusions are generalisable (supported by the example of Berlin). The most advantageous shape of the tram's front, minimising the effects on pedestrians in all collision phases, has evolved rather spontaneously and was unprompted, and it is now being built into the European Commission regulations. The goal of the second part of this paper is to conduct a series of tram-pedestrian collisions with a focus on the frontal and side impacts using a crash test dummy (anthropomorphic test device-ATD). Four tram types approaching the collision at four different impact speeds (5 km/h, 10 km/h, 15 km/h, and 20 km/h) were used. The primary outcome variable was the resultant head acceleration. The risk and severity of possible head injuries were assessed using the head injury criterion (HIC15) and its linkage to the injury level on the Abbreviated Injury Scale (AIS). The results showed increasing head impacts with an increasing speed for all tram types and collision scenarios. Higher values of head acceleration were reached during the frontal impact (17-124 g) compared to the side one (2-84 g). The HIC15 values did not exceed the value of 300 for any experimental setting, and the probability of AIS4+ injuries did not exceed 10%. The outcomes of tram-pedestrian collisions can be influenced by the ATD's position and orientation, the impact speed and front-end design of trams, and the site of initial contact.

Pedestrian Safety in Frontal Tram Collision, Part 2: Laminated Glass as a Crucial Part of the Absorption and Deformation Zone-Its Impact Test and Analysis.

As was shown in the previous part of the study, windshields are an important part of the passive safety means of modern low-floor trams with an extraordinary effect on pedestrian safety in a pedestrian-tram collisions. Therefore, maximum attention must be paid to the definition of tram windshield characteristics. This article describes a windshield crash test, from which data are obtained to verify the feasibility of the applied computational approaches. A developed analytical model is utilised for a simple description of the energy balance during collision with an illustrative definition of the important parameters of laminated glass as well as their clear physical interpretations. The finite element analysis (FEA) performed in Ansys software using two versions of material definition, namely a simpler (*MAT_ELASTIC with nonlocal failure criterion) and a more complex (*MAT_GLASS with brittle stress-state-dependent failure) material model, which are presented as suitable for obtaining a detailed description of the shattering process of laminated glass, which can also be used effectively in windshield engineering.

Patellofemoral pain syndrome assessed by Lysholm score, radiological and biorheometric measurements.

INTRODUCTION: The aim of In this study was to verify the relationship among clinical indicators of patellofemoral pain syndrome (PFPS) and the results of modifying radiological investigation. Previous research suggests that there is a poor association between them. Therefore we have employed a technique for the functional evaluation of PFPS based on measuring the stiffness of the knee joint during passive flexion (biorheometry). METHOD: The correlation between clinical examination and a standardized Lysholm score, radiological and biorheometric measures was investigated in the 28 knee joints of 14 subjects exhibiting clinical features of PFPS. A modified axial radiological projection of the patellofemoral articulation in 90° of flexion provided the parameters quantifying the anatomical - morphological arrangement of the patellofemoral joint. The biorheometric properties of the knee were evaluated using a custom made measuring apparatus during passive flexion and extension of the knee. RESULTS: Our results confirm that the link between the clinical findings and the X-ray imaging examinations was not evident. On the contrary, the biorheometric examination proved to correlate well with the clinical symptoms of PFPS. Parameters were identified which can characterize the biorheograms of people suffering PFPS. CONCLUSIONS: Analysis of the relationship among the clinical, radiological and biorheometric examinations leads to the recommendation that biorheometric examination is an effective method for the objective assessment of PFPS.

Principal Component Analysis can Be Used to Discriminate Between Elite and Sub-Elite Kicking Performance.

Contemporary descriptions of motor control suggest that variability in movement can be indicative of skilled or unskilled performance. Here we used principal component analysis to study the kicking performance of elite and sub-elite soldiers who were highly familiar with the skill in order to compare the variability in the first and second principal components. The subjects kicked a force plate under a range of loaded conditions, and their movement was recorded using optical motion capture. The first principal component explained >92% of the variability across all kinematic variables when analyzed separately for each condition, and both groups and explained more of the variation in the movement of the elite group. There was more variation in the loading coefficient of the first principal component for the sub-elite group. In contrast, for the second principal component, there was more variation in the loading coefficient for the elite group, and the relative magnitude of the variation was greater than for the first principal component for both groups. These results suggest that the first principal component represented the most fundamental movement pattern, and there was less variation in this mode for the elite group. In addition, more of the variability was explained by the hip than the knee angle entered when both variables were entered into the same PCA, which suggests that the movement is driven by the hip.

Low Concentrated Fractionalized Nanofibers as Suitable Fillers for Optimization of Structural-Functional Parameters of Dead Space Gel Implants after Rectal Extirpation.

Dead space after rectal resection in colorectal surgery is an area with a high risk of complications. In this study, our goal was to develop a novel 3D implant based on composite hydrogels enriched with fractionalized nanofibers. We employed, as a novel approach in abdominal surgery, the application of agarose gels functionalized with fractionalized nanofibers on pieces dozens of microns large with a well-preserved nano-substructure. This retained excellent cell accommodation and proliferation, while nanofiber structures in separated islets allowed cells a free migration throughout the gel. We found these low-concentrated fractionalized nanofibers to be a good tool for structural and biomechanical optimization of the 3D hydrogel implants. In addition, this nano-structuralized system can serve as a convenient drug delivery system for a controlled release of encapsulated bioactive substances from the nanofiber core. Thus, we present novel 3D nanofiber-based gels for controlled release, with a possibility to modify both their biomechanical properties and drug release intended for 3D lesions healing after a rectal extirpation, hysterectomy, or pelvic exenteration.

Kinematic Determinants of Front Kick Dynamics Across Different Loading Conditions.

INTRODUCTION: The efficiency of front kick is related to the kicking technique. Thus, the aim of this study was to find the kinematic determinants of front kick dynamics across different performance and loading levels (no load to 45-kg load). MATERIALS AND METHODS: Twenty-four elite and sub-elite professional military personnel (26.8 ± 10.1 years, 84.2 ± 5.4 kg, 181.1 ± 6.4 cm) performed six front kicks into a force plate across five different loading conditions. Three-dimensional kinematics of the kicks was quantified and included velocity of the hip (Vhip), velocity of the knee (Vknee), velocity of the shoulder (Vshoulder), velocity of the foot (Vfoot), angular velocity of the knee (AVknee), and angular velocity of the hip (AVhip). RESULTS: The main kinematic differences between the two groups were that the sub-elite group had an increased kick time for all loading conditions (P < .001) and a lower Vfoot (P = .05) and a decreased Vhip and Vshoulder (P < .05) in the highest load condition. Vhip and AVhip were the best predictors (up to R2 = 0.58; P = .020) of peak force and impact force during no-load or loaded kicking at the elite level. Typical predictors of impulse in the elite group were AVhip, Vhip, and Vshoulder and those in the sub-elite group were AVknee and Vfoot. CONCLUSIONS: The kinematic variables provide good predictions of kicking dynamics; however, the best predictor varies with the loading conditions and performance levels. Hip motion is the main differentiating factor.

Selected biomechanical aspects of the asymmetrical loading of the human postural system when riding the C1 speed canoe and their influence on the development of muscular imbalances.

OBJECTIVES: The main aim of this study was to analyse selected biomechanical aspects of the asymmetrical loading of the human postural system when riding the C1 speed canoe and their influence on the development of muscular imbalances. METHODS: 3D kinematic analysis of a simulated forward stroke of the canoeist in a pool with a counter-current (N = 9) and analysis of MRI data with selected individuals (N = 5), videoanalysis of actual paddling top athletes (N = 12), the kinesiological analysis of movement. RESULTS: Can be stated that when riding a C1 speed canoe the postural system is exposed to two types of asymmetric loading. In the first place, there is lateral asymmetry, which stems from the very nature of the one-sided paddling on this type of vessel. The canoeist has to compensate for the consequent instability by shifting the body's centre of gravity higher above the kneeling lower limb. This effect is achieved by the so-called pelvic lateralisation from the paddling side and by this side's skewing to the kneeling lower limb. Another asymmetry is connected to the forward-backward body movement and its time-dependent deviation from the neutral posture. A significant disproportion between generally fixation movements of the lower part of the body and phasic movements of the upper part of the body has been confirmed. These asymmetrical positions result in a significant unilateral overloading of the quadratus lumborum on the side of the supporting lower limb (side without the paddle), as well as an overloading of the spine straighteners in the lumbar area, in particular on the part of a supporting lower limb, and bilateral yet asymmetric overloading of m. iliopsoas, which in addition takes place in different isometries. The analysis of MRI data indicates that, during longitudinal training, lateral disproportion in the volume and intensity of postural system loading is the cause of different cross sections of the iliopsoas muscle and quadratus lumborum muscle on the side of the kneeling and supporting lower limbs. With both muscles, larger cross sections with a statistical significance level α = 0.05 and thus also strength on the side of the supporting lower limb can be expected. CONCLUSION: When canoeing on the C1, a significant unilateral overloading occurs with m. quadratus lumborum on the part of the supporting lower limb (side without paddle). Furthermore, spine straighteners in the lumbar area are overloaded, in particular in the part of the supporting lower limb. Last but not least however, the bilateral asymmetric overloading of m. iliopsoas occurs.

The effect of breathing technique on sticking region during maximal bench press.

The intrathoracic pressure and breathing strategy on bench press (BP) performance is highly discussed in strength competition practice. Therefore, the purpose of this study was to analyze whether different breathing techniques can influence the time and track characteristics of the sticking region (SR) during the 1RM BP exercise. 24 healthy, male adults (age 23 ± 2.4 yrs., body mass 85 ± 9.2 kg, height 181 ± 5.4 cm) performed a 1 repetition BP using the breathing technique of Valsalva maneuver (VM), hold breath, lung packing (PAC), and reverse breathing (REVB), while maximum lifted load and concentric phase kinematics were recorded. The results of ANOVA showed that the REVB breathing decreased absolute (p < 0.04) and relative lifted load (p < 0.01). The VM showed lower (p = 0.01) concentric time of the lift than the other breathing techniques. The VM and PAC showed lower SR time than other breathing techniques, where PAC showed a lower SR time than VM (p = 0.02). The PAC techniques resulted in shorter SR and pre-SR track than other breathing techniques and the REVB showed longer SR track than the other considered breathing techniques (p = 0.04). Thus, PAC or VM should be used for 1RM BP lifting according to preferences, experiences and lifting comfort of an athlete. The hold breath technique does not seem to excessively decrease the lifting load, but this method will increase the lifting time and the time spend in the sticking region, therefore its use does not provide any lifting benefit. The authors suggest that the REVB should not be used during 1 RM lifts.

Load Measurement of the Cervical Vertebra C7 and the Head of Passengers of a Car While Driving across Uneven Terrain.

The article deals with the measurement of dynamic effects that are transmitted to the driver (passenger) when driving in a car over obstacles. The measurements were performed in a real environment on a defined track at different driving speeds and different distributions of obstacles on the road. The reaction of the human organism, respectively the load of the cervical vertebrae and the heads of the driver and passenger, was measured. Experimental measurements were performed for different variants of driving conditions on a 28-year-old and healthy man. The measurement's main objective was to determine the acceleration values of the seats in the vehicle in the vertical movement of parts of the vehicle cabin and to determine the dynamic effects that are transmitted to the driver and passenger in a car when driving over obstacles. The measurements were performed in a real environment on a defined track at various driving speeds and diverse distributions of obstacles on the road. The acceleration values on the vehicle's axles and the structure of the driver's and front passenger's seats, under the buttocks, at the top of the head (Vertex Parietal Bone) and the C7 cervical vertebra (Vertebra Cervicales), were measured. The result of the experiment was to determine the maximum magnitudes of acceleration in the vertical direction on the body of the driver and the passenger of the vehicle when passing a passenger vehicle over obstacles. The analysis of the experiment's results is the basis for determining the future direction of the research.

Isokinetic Strength of Rotators, Flexors and Hip Extensors is Strongly Related to Front Kick Dynamics in Military Professionals.

Achieving the maximum possible impact force of the front kick can be related to the isokinetic lower limb muscle strength. Therefore, we aimed to determine the regression model between kicking performance and the isokinetic peak net moment of hip rotators, flexors, and hip extensors and flexors at various speeds of contraction. Twenty-five male soldiers (27.7 ± 7.2 yrs, 83.8 ± 6.1 kg, 180.5 ± 6.5 cm) performed six barefoot front kicks, where impact forces (N) and kick velocity (m∙s-1) were measured. The 3D kinematics and isokinetic dynamometry were used to estimate the kick velocity, isokinetic moment of kicking lower limb hip flexors and extensors (60, 120, 240, 300°âˆ™s-1), and stance lower limb hip internal and external rotators (30, 90°âˆ™s-1). Multiple regression showed that a separate component of the peak moment concentric hip flexion and extension of the kicking lower limb at 90°âˆ™s-1 can explain 54% of the peak kicking impact force variance (R2 = 0.54; p < 0.001). When adding the other 3 components of eccentric and concentric hip internal and external rotations at 30°âˆ™s-1, the internal and external hip rotation ratios at 30°âˆ™s-1 on the stance limb and the concentric ratio of kicking limb flexion and extension at 300°âˆ™s-1 that explained the variance of impact force were 75% (p = 0.003). The explosive strength of kicking limb hip flexors and extensors is the main condition constraint for kicking performance. The maximum strength of stance limb internal and external rotators and speed strength of kicking limb hip flexors and extensors are important constraints of kicking performance that should be considered to improve the front kick efficiency.

In vivo assessment of time dependent changes of T2* in medial meniscus under loading at 3T: A preliminary study.

Due to the internal structure of the knee joint, the ability to characterize and quantify the dynamic response of the meniscal tissue directly in vivo is highly problematic. The main purpose of this study was to investigate the behaviour of the meniscus under loading conditions. Four healthy young females were included. To obtain T2* values in the meniscus, the vTE sequence was used with 10 echoes ranging from 0.8 to 10.1 ms. Submilisecond first echo time is a great advantage of vTE sequence allowing for precise mapping of relatively short T2*. The two-parametric least squares fitting procedure was used to calculate T2* pixel-wise. A custom-made diamagnetic apparatus was developed to simulate stress conditions on the lower limb in a conventional MR scanner. vTE T2* was performed in five consecutive scans, 6:10 min apart. Three different compartments of the medial and lateral meniscus were segmented. The differences at the different time-points were calculated. A constant increase of T2* times after compression was statistically significant in the anterior horn of the medial meniscus. T2* mapping with variable echo time sequence might be a satisfactorily sensitive technique to detect the changes of meniscus physiology under loading conditions in vivo.

Kinetic and Kinematic Differences in a Golf Swing in One and Both Lower Limb Amputees.

Amputee golfers need to cope with the absence of sole proprioception, a decreased range of swing motion and other factors which should be recognized for training purposes. The aim of this study was to determine the kinetic and kinematic differences in the golf swing in one leg and two legs amputees. The participants consisted of two males and one female at a professional or amateur level with a different degree of disability. Each participant was taped by 3D markers and performed five golf swings with the iron 6. The intraclass correlation coefficient (ICC) did not vary between individuals in kinematics, however, it was low in kinetic variables of two leg amputees. The Kendal rank correlation showed a significant relationship between the level of amputation and a large number of kinetic and kinematic variables such as X factor, O factor, S factor and individual body angles. The fluency and similarity of the golf swing did not depend on the level of amputation. One lower limb amputation did not seem to increase movement variability contrary to two lower limb amputation. The most variable parameter was a weight-shift in all golfers. The takeaway and horizontal force angle depended on the level of amputation rather than individual technique, thus, their modification by training may be difficult. Estimation of golf swing "mistakes" in amputees in respect to the leading arm in an early follow or late follow position appeared to be useless.

Kinematic and dynamic biomechanical values in relation to muscle activity during contact head impact.

OBJECTIVE: For the evaluation of neck injury the relative distance was observed between a marker placed on the forehead and a marker placed on the shoulder and also by change of the angle. To compare the severity of head injury a value of maximum head acceleration was used, HIC and a 3 ms criterion. All criteria were related to the activity of musculus sternocleidomastoideus and musculus trapezius in a situation of expected or unexpected contact impact. MATERIALS AND METHODS: The situation was recorded using a Qualisys system, head acceleration of probands in three axes was recorded using the accelerometer, activity of neck muscles was monitored by a mobile EMG. RESULTS: Maximum head acceleration was 5.61 g for non-visual and 5.03 g for visual. HIC36 was 6.65 non visual and 5.97 for visual. 3-ms criterion was 5.37 g for non-visual and 4.89 g for visual and max. force was 291 N for non-visual and 314 N for visual. The average time of muscle activation of the observed group without visual perception is 0.355 s after hitting an obstacle, with visual perception 0.085 s before the crash. CONCLUSIONS: Kinematic values indicate more favourable parameters for neck injuries for visual. Head injury criteria show an average decrease of about 10% for visual. We can conclude that the visual perception means a significant increase in pre-activation of the observed muscle group of almost 745% and lower activation in following phase of approximately 90%.

Pre-activation and muscle activity during frontal impact in relation to whiplash associated disorders.

OBJECTIVE: For the evaluation of neck injury the relative distance was observed between a marker placed on the forehead and a marker placed on the shoulder and also by change of the angle. To compare the severity of head injury a value of maximum head acceleration was used, HIC and a 3 ms criterion. All criteria were related to the activity of musculus sternocleidomastoideus and musculus trapezius in a situation of expected or unexpected impact. MATERIALS AND METHODS: The situation was recorded using a Qualisys system, head acceleration of probands in three axes was recorded using the accelerometer, activity of neck muscles was monitored by a mobile EMG. RESULTS: Maximum head acceleration was 12.1 g for non-visual and 8.2 g for visual. HIC36 was 5.7 non visual and 4.0 for visual. 3-ms criterion was 11.5 g for non-visual and 7.8 g for visual. The average time of muscle activation of the observed group without visual perception is 0.027 s after hitting an obstacle, with visual perception 0.127 s before the crash. CONCLUSIONS: Kinematic values indicate more favourable parameters for neck injuries for visual. Head injury criteria show an average decrease of about 30% for visual. We can conclude that the visual perception means a significant increase in pre-activation of the observed muscle group of almost 400% and lower activation in both following phases of approximately 40%.

Influence of SYSADOA group chemicals on progression of human knee joint osteoarthritis: new objective evaluation method - measuring of rheological properties in vivo.

OBJECTIVES: This study seeks to demonstrate the influence of pharmacological substances from the SYSADOA group on the progression of osteoarthritis in the human knee. The quantification methods were direct measurement of the rheological properties of the knee joints in vivo and standard WOMAC index questionnaires. MATERIALS AND METHODS: The drugs were administered orally to 34 probands with second degree gonarthrosis for 13 weeks. The untreated control group consisted of 10 probands. The rheological properties of the joints were determined by a biorheometer, and subjective assessment of the knees by patients (WOMAC) before and after medication, and for a further 13 weeks. Changes in the calculated parameters over time were compared. RESULTS: During the audited perioda slight deterioration in all of the parameters was observed in the untreated group. The treated group, however, improved in all the parameters and some indicators showed statistically significant differences. The positive effects of the SYSADOA persisted for 3 months after the end of treatments. Partial correlation was found between the results of the WOMAC questionnaire and the rheological measurements. CONCLUSIONS: This study shows the positive effects of the preparation on arthritic changes in the knee joint, but due to the large variance of the collected data, this conclusion is on the borderline of statistical significance. The method of measuring the rheological properties of the joints is suitable for evaluating the progression of OA.

Changes in attenuation characteristics of axial system of pregnant drivers detected by the TVS method.

OBJECTIVES: During a longer car drive there are changes in rheological properties of driver's or passenger's connective tissues taking place as a consequence of monotonous and vibration load. These changes show more among the pregnant drivers, whose motion system is under heavier demands due to pregnancy. To asses these changes we have used the TVS (transfer vibration through the spine) method. METHODS: The TVS is based on application of γ excitation pulses with half-length 5 ms and then harmonic excitation continuously periodically changing from 5 Hz to 160 Hz on C7 and L5 vertebrae. This wave is transferred along the axial system and the acceleration of all the spinous tips of the vertebrae, along which the waves spread between C7 and S1, is detected by accelerometric sensors. The measurement was carried out on three drivers before and after a 4-hours driving. The same measurements of wave transfer along the spine with just one pregnant woman were carried out in th 16th, 26th and 32nd week of pregnancy. Consequently we constructed a simplified model of the spine in order to analyze gathered data by discovering elementary properties of the measured system. RESULTS: After both vibration and physical load there is a more significant dampening of the spinal tissues apparent, i.e. lower acceleration amplitude and the tissues resonance frequency also shifts towards the lower frequencies. On the other hand after long lasting relaxation on a bed an opposite tendency showed, the acceleration amplitude was higher, tissues were relaxed and dampening was lower. The same tendency manifested among the pregnant women. The influence of progressing pregnancy on the spinal segment transfer function showed through a shifting of peaks above 20Hz. Their size also changes monotonously. An absorption area moves towards higher frequencies, rigidity of axial system connections grows. CONCLUSION: The results say that drivers, including pregnant women, show changes in mechanical properties of examined tissues before and after vibration or other type of load. Or conversely before and after relaxation on a bed. Results of this work will be further analyzed, verified and evaluation procedures will be improved. We expect to find dependencies between excitation and resonance frequencies during the transfer via the axial system, the rheological properties of the axial system components and the physical nature of the load of the axial system. They are then going to be applicable for the prevention of injuries of the axial system, physiotherapy practices in the rehabilitation of post-operative conditions, the dosage of training loads of athletes, in determining the effects of job stress regimes and their prevention.

Biomechanical factors influencing the beginning and development of osteoarthritis in the hip joint.

Osteoarthritis (OA) can be used as a common name for a group of overlapping pathological conditions when the balance between the processes of degradation and synthesis, in individual parts of the cartilage, is disturbed and leads to gradual cartilage destruction. A preventive approach toward OA helps with a timely diagnosis and subsequent treatment of this disease. One of the significant risk factors affecting development of hip joint OA is the mechanism and magnitude of mechanical loading on the joint. The main motivation for this work was to verify the hypothesis involving a pathologic cycle (overloading - change of locomotion - overloading) as contributory to the development of OA and whether it can be stopped, or at least partly decelerated, by a suitable change of movement stereotypes. Providing that there is a natural balance of muscular action, from the beginning of OA, the development of OA can be significantly decelerated. The return to a natural force balance can be achieved using suitable exercise and strengthening of muscular structures. In order to verify the hypothesis, we undertook experimental measurements of gait kinematics and a computational analysis of the hip joint using the Finite Element Method.

Women with incorrect pelvic floor statics: a biomechanical answer to the mechanical loading of the vagina-endopelvic fascia complex.

OBJECTIVE: This work focuses on finding method for detecting the elementary mechanical characteristics of the vagina-endopelvic fascia complex, aimed at providing results for use in optimizing solutions for stability defects of the pelvic floor. MATERIALS AND METHODS: Two experiments have already been carried out that have enabled monitoring of the reaction of tissue complex samples to a selected load. The elastic properties of samples under a simple pull load were evaluated. The monitored property in the first experiment was the maximum reference tension at the moment of rupture of the sample in relation to the non-deformed section. We evaluated data from measurements on 11 samples within the scope of the first experiment. For data processing from the second experiment we used a linear-elastic model of the sample, formed by parallel connection of basic mechanical elements - springs - that represented the endopelvic fascia and the vaginal wall. The relevant rigidities were used for a description of their properties. Five samples were used for this experiment. RESULTS: An important discovery was that the endopelvic fascia tears apart after a longer period of time than the vaginal wall during the pull test. The results show considerable variability among individuals, but the pattern of curves is similar in all test cases. In all measured data we found a rigidity increase zone, a maximum rigidity zone and a gradual rigidity decrease zone before terminal damage in the response. CONCLUSIONS: The results presented here show quite broad interindividual variability of the mechanical properties of the vaginal wall-endopelvic fascia complex. It appears that the mechanical properties of the tissue complex change with number of pregnancies, and are affected by diseases, by physical load or by the presence of other factors, e.g. obesity.

Forensic biomechanical analysis of falls from height using numerical human body models.

This article describes the method of using human body models developed originally for the use in automotive safety in forensic reconstructions of falls from height. The MADYMO(®) software package and multibody human body models were used in forensic analyses of two real cases--a fatal fall from a window c. 13.8 m above the ground and a fall into a c. 2.5-m deep cellar pit resulting in isolated ankle joint injury. The performed series of numerical simulations helped to reconstruct the events and to resolve legally relevant questions concerning various aspects of the falls. The benefits as well as limitations and potential biases associated with the use of numerical simulation in forensic biomechanical settings are discussed. The method has proven to be effective under specific circumstances, though the cost (both financial and temporal) still prevents it from wider use.