Klaus Peikenkamp

Simulating the Impact During Human Jumping by Means of a 4-Degrees-of-Freedom Model With Time-Dependent Properties

Abstract The authors simulated the vertical movements of a jumper and the force time courses by means of a 4-degrees-of-freedom model consisting of 4 masses, springs, and dampers. Of the motions simulated, only that of the mass imitating the trunk corresponded to the measured data. The best fit to the measured force curves were obtained in the simulation in which time-dependent model parameters were used. From the results, the authors concluded that at the beginning of the landing, a jumper behaves like a 2-mass model in which the leg segments (thighs, shanks, and feet) effectively combine into 1 mass. After approximately 60 ms, the connections between the leg segments become more compliant and the jumper behaves like a 4-mass model with a soft coupling between the leg segments. The process is equivalent to an increase of the degrees of freedom of the movements. At the end of the ground contact phase during hopping, the jumper has to contract the muscles in order to reach the envisaged jump height. In the model, that contraction could not be satisfactorily simulated.

A new insole measurement system to detect bending and torsional moments at the human foot during footwear condition: a technical report

BackgroundStress occurring at the feet while wearing footwear is often determined using pressure measurement systems. However, other forms of stress, such as bending, torsional and shear loadings, cannot be detected in shoes during day-to-day activities. Nevertheless, the detection of these types of stresses would be helpful for understanding the mechanical aspects of various kinds of hard and soft tissue injuries. Therefore, we describe the development of a new measuring device that allows the reliable determination of bending and torsional load at the foot in shoes.MethodsThe system consists of a measuring insole and an analogue device with Bluetooth interface. The specific shape of the insole base layer, the positions of the strain gauges, and the interconnections between them have all been selected in such a way so as to isolate bending and torsional moment detections in the medial and lateral metatarsal region. The system was calibrated using a classical two-point test procedure. A single case study was executed to evaluate the new device for practical use. This application consisted of one subject wearing neutral shoes walking on a treadmill.ResultsThe calibration results (coefficients of determination R2 > 0.999) show that bending and torsional load can be reliably detected using the measurement system presented. In the single case study, alternating bending and torsional load can be detected during walking, and the shape of the detected bending moments can be confirmed by the measurements of Arndt et al. (J Biomech 35:621–8, 2002).ConclusionsDespite some limitations, the presented device allows for the reliable determination of bending and torsional stresses at the foot in shoes.

Simulation of the complex countermovement jumping by means of a simple four-degrees-of-freedom model

By means of a four-degrees-of-freedom model the vertical movements of an athlete and the time course of the ground reaction force were simulated during a countermovement jump on a concrete and a wooden surface. The model masses were connected to each other and to the surface by springs and dampers. At first the stiffness of the springs decreased in order to initiate the countermovement. Afterwards the stiffness increased like the muscle activity so that the flexion of the model ‘legs’ were decelerated before the extension starts. The best result was attained when the stiffness of the spring between the model masses ‘thighs’ and ‘trunk’ increased before the other three springs. Compared with the muscle activity this means that for a successful jump the upper body segments have to be accelerated before the segments near to the ground are accelerated. The model ‘athlete’ was connected to a model of the surface. It could be shown that the jump on a concrete surface results in a better jump height than the jump on an elastic wooden surface if the muscle activation is not adapted to the surface properties.

Probleme bei der Bestimmung der äußeren Belastung auf einem Schwingboden

Das Messen der auseren und die Berechnung der inneren Belastung der unteren Extremitaten bei Landungen war bereits haufig Gegenstand biomechanischer Untersuchungen. Dieser Untersuchungsgegenstand ist auch bzgl. einiger Hallensportarten wie z. B. Volleyball und Handball von besonderem Interesse. Hierbei ergibt sich das Problem, das die bei den Landungen auftretenden Belastungen auch von der Beschaffenheit des Hallenbodens abhangen. Wird dieser Aspekt nicht berucksichtigt und werden die Messungen lediglich unter Laborbedingungen vorgenommen, weicht die gemessene ausere Belastung von der unter realen (Hallen)Bedingungen erzeugten Belastung des Athleten ab. Gleiches gilt dann auch fur Simulationsergebnisse, wenn die unter Laborbedingungen gewonnenen Mesergebnisse als Eingabeparameter fur Modelle der unteren Extremitaten zur Bestimmung innerer Belastungsgrosen verwendet werden — unabhangig von der Qualitat des Modells.

Bending loads of the foot in forefoot offloading shoes and walkers

might be a reason why women are not as capable of resisting external stimuli like footwear. Due to a lack of methods to distinctly identify the PMP for each joint, it is not safe to say footwear in this study really forced lower extremity joints to operate outside their PMP. Shoe sensitivity is, however, an indicator of how susceptible to external stimuli a person’s running style is. The risk of injury due to wearing the wrong footwear is certainly higher in shoe-sensitive runners. That is why the choice of the right footwear design supporting the PMP gains even more importance with shoe-sensitive athletes.

Bending and torsional stress detection at the human foot during footwear conditions

Stress detection at the feet during footwear conditions is of great interest in the prevention of overstressing in orthopaedics, surgery and sports (Lieberman et al., 2010; Long et al., 2007). Until now, loads acting at the lower limb and the feet were determined with measurement systems using single pressure sensors, strips or insoles with pressure sensors. Other mechanical variables except pressure, such as bending, torsional moments and shear forces, cannot yet be detected in daily practice (Chen et al., 2010). But these loads in various forms could play an important role in the cause of disease and trauma at the lower limb and feet (Arndt, Ekenman, & Lundberg, 2002).

The use of pressure distribution for the analysis of passing and shooting techniques in soccer

An exact passing technique is a necessary precondition for success in soccer. Consequently, a techniques control represents an important part during training. However, the time of impact between f...

The influence of rocker soles on bending loads acting on the forefoot during walking and slow jogging

591 598. Fisher, D.S., Dyrby, C.O., M€undermann, A., Morag, E.M., & Andriacchi, T.P. (2007). In healthy subjects without knee osteoarthritis, the peak knee adduction moment influences the acute effect of shoe interventions designed to reduce medial compartment knee load. Journal of Orthopaedic Research, 25, 540 546. Radzimski, A.O., M€undermann, A., & Sole, G. (2012). Effect of footwear on the external knee adduction moment a systematic review. The Knee, 19, 163 175.

COMPARISON OF DIFFERENT HEEL PADS VARYING IN SHORE HARDNESS

Heel pads are commonly used for the treatment of plantar heel pain, plantar fasciitis and knee arthrosis, which might lead to discomfort during walking and running. Force plates as well as foot pressure measurement systems are well accepted for clinical examination of gait analysis. In this study the effect of three different heel pads (variation in Shore hardness) was evaluated with respect to the validation of using both measurement systems in combination.

INFLUENCES OF SPECIAL FOOTORTHOSES ON EMG AND PLANTAR PRESSURE IN PATIENTS WITH LOW BACK PAIN

Bourdiol developed an insole concept with so called Neuromuscular Operating Elements (NME). By influencing the plantar foot sensibility with NME, reflexes should activate so called muscle chain reactions and as a result of that, malposition of the whole locomotors system should be treated. New footorthoses(FO)-concepts use the NME. But they are controversially discussed, cause of the missing scientific background. In contrast to these FO, classical ones like Custom Moulded FO (CMFO) focus on lower limb problems [Collins et al]. Their effects are quiet validated [Murley et al]. So the aim of this study was to test the influences of CMFO with NME (Figure 1; total left) on muscle activation and plantar pressure distribution.