The natural frequency of the foot-surface cushion during the stance phase of running (original) (raw)
Related papers
Parameter identification for vertical ground reaction forces on feet while running
Sports Engineering, 2015
The human foot is subjected to ground reaction forces during running. These forces have been studied for decades to reduce the related injuries and increase comfort. A four-degree-of-freedom system has been used in the literature to simulate the human body motion during the touchdown. However, there are still inconsistencies between the simulation results and experimental measurements. In this study, an optimization technique is proposed to obtain the required parameters to estimate the vertical ground reaction force using the measurements from actual runners. The touchdown velocities of the rigid and wobbling body masses were also treated as optimization variables. It was shown that the proposed parameters can be adjusted to represent a particular shoe type. Specifically, vertical ground reaction force parameters and touchdown velocities were obtained for shoes with various insole properties and cushioning technologies. The results of this study suggest that the human locomotion system reacts to the shoe properties by regulating the velocities of the body wobbling and rigid masses. The magnitude and the load rate obtained using the proposed parameters are consistent with the experimental data. It is shown that the viscoelastic properties of the shoe will significantly affect the load rate but not the load magnitude.
Journal of Biomechanics, 2010
A previously developed mass-spring-damper model of the human body is improved in this paper, taking muscle activity into account. In the improved model, a nonlinear controller mimics the functionality of the Central Nervous System (CNS) in tuning the mechanical properties of the soft-tissue package. Two physiological hypotheses are used to determine the control strategies that are used by the controller. The first hypothesis (constant-force hypothesis) postulates that the CNS uses muscle tuning to keep the ground reaction force (GRF) constant regardless of shoe hardness, wherever possible. It is shown that the constant-force hypothesis can explain the existing contradiction about the effects of shoe hardness on the GRF during running. This contradiction is emerged from the different trends observed in the experiments on actual runners, and experiments in which the leg was fixed and exposed to impact. While the GRF is found to be dependent on shoe hardness in the former set of experiments, no such dependency was observed in the latter. According to the second hypothesis, the CNS keeps the level of the vibrations of the human body constant using muscle tuning. The results of the study show that this second control strategy improves the model such that it can correctly simulate the effects of shoe hardness on the vibrations of the human body during running.
Study on estimation of peak Ground Reaction Forces using tibial accelerations in running
2013 IEEE Eighth International Conference on Intelligent Sensors, Sensor Networks and Information Processing, 2013
Ground Reaction Forces (GRF) are exerted by a surface as a reaction to a person standing, walking or running on the ground. In elite and recreational sports, GRFs are measured and studied to facilitate performance improvement and enhance injury management. Although, GRFs can be measured accurately using force platforms, such a hardware can only operate in a constrained laboratory environment and hence may limit and potentially alter a subject's natural walking or running pattern. Alternatively, a system that can measure GRFs in a more natural environment with less constraints can provide valuable insights of how humans move naturally given different gait patterns, terrain conditions and shoe types. In this regard, inertial Micro-Electrical-Mechanical-Sensors (MEMS), such as accelerometers and gyroscopes, are a promising alternative to laboratory constrained data collection systems. Kinematics of various body parts, such as their accelerations and angular velocities, can be quantified by attaching these sensors at points of interest on human body. In this paper, we investigate the relationship between the vertical GRF peaks measured by an OR6 series AMTI force plate, and accelerations along the tibial axis measured by a MEMS sensor. Our measuring system consists of two low-power wireless inertial units (ViPerform), containing one tri-axis accelerometer placed on the medial tibia of each leg. We investigate the accuracy of the measured and estimated GRF peak in 3 subjects, by means of the Root Mean Square Error (RMSE). The RMSE achieved across the speeds of 6, 9, 12, 15, 18, 21km/h and sprinting were 157 and 151N , 106 and 153N , and 130 and 162N for the left and right legs respectively for Subjects 1, 2, and 3. We achieved normalized errors of 6.1%, 5.9% and 5.4% for all the subjects.
A model-based parametric study of soft tissue vibrations during running
A lumped-parameter four-degree-of-freedom model of the human body was previously developed. Subsequently, the model was modified by such that the simulation results for the ground reaction forces matched the experimental results. In this paper, the corrected version of the above-mentioned model is used to study the effects of different model parameters and shoe hardness on the softtissue package vibrations.
Journal of Biomechanics, 2019
The purpose of this study is to examine the effect of the body's mass distribution to segments and the filtering of kinematic data on the estimation of vertical ground reaction forces from positional data. A public dataset of raw running biomechanics was used for the purposes of the analysis, containing recordings of twenty-eight competitive or elite athletes running on an instrumented treadmill at three different speeds. A grid-search on half of the trials was employed to seek the values of the parameters that optimise the approximation of biomechanical loads. Two-way ANOVAs were then conducted to examine the significance of the parameterised factors in the modelled waveforms. The reserved recordings were used to validate the predictive accuracy of the model. The cutoff filtering frequencies of the pelvis and thigh markers were correlated to running speed and heel-strike patterns, respectively. Optimal segment masses were in agreement with standardised literature reported values. Root mean square errors for slow running (2.5 m=s) were on average equal to 0.1 (body weight normalized). Errors increased with running speeds to 0.13 and 0.18 for 3.5 m=s and 4.5 m=s, respectively. This study accurately estimated vertical ground reaction forces for slow-paced running by only considering the kinematics of the pelvis and thighs. Future studies should consider configuring the filtering of kinematic inputs based on the location of markers and type of running.
Use of Ground Reaction Force Parameters in Predicting Peak Tibial Accelerations in Running
Journal of Applied Biomechanics, 1993
Ground reaction force data and tibial accelerations from a skin-mounted transducer were collected during rearfoot running at 3.3 m/s across a force platform. Five repetitive trials from 27 subjects in each of 19 different footwear conditions were evaluated. Ground reaction force as well as tibial acceleration parameters were found to be useful for the evaluation of the cushioning properties of different athletic footwear. The good prediction of tibial accelerations by the maximum vertical force rate toward the initial force peak (r2 = .95) suggests that the use of a force platform is sufficient for the estimation of shock-absorbing properties of sport shoes. If an even higher prediction accuracy is required a regression equation with two variables (maximum force rate, median power frequency) may be used (r2 = .97). To evaluate the influence of footwear on the shock traveling through the body, a good prediction of peak tibial accelerations can be achieved from force platform measurem...
The effects of footwear on impact force during running: a model-based study
A lumped-parameter model of the human body during running was previously developed. The model was used to study the effects of footwear on the impact force during running. However, the parameters of the model were considered constant regardless of the shoe type. Experimental studies have shown that the stiffness and damping of the human body are adjusted in accordance with the stiffness and damping of the shoe-ground system. In this paper, we study how the parameters of the model are adjusted, when the shoe parameters change. The original model is improved by adding a controller which resembles the function of the CNS. The effects of footwear on the impact force are studied by using the improved model. Three different bound limits are used for the model parameters to study the effects of the upper and lower parameter limits on the results. It has been shown that the model can explain the contradictory observations about the effects of footwear on the impact force.
Foot speed, foot-strike and footwear:linking gait mechanics and running ground reaction forces
Journal of Experimental Biology, 2014
Running performance, energy requirements and musculoskeletal stresses are directly related to the action-reaction forces between the limb and the ground. For human runners, the force-time patterns from individual footfalls can vary considerably across speed, footstrike and footwear conditions. Here, we used four human footfalls with distinctly different vertical force-time waveform patterns to evaluate whether a basic mechanical model might explain all of them. Our model partitions the body's total mass (1.0M b ) into two invariant mass fractions (lower limb=0.08, remaining body mass=0.92) and allows the instantaneous collisional velocities of the former to vary. The best fits achieved (R 2 range=0.95-0.98, mean=0.97±0.01) indicate that the model is capable of accounting for nearly all of the variability observed in the four waveform types tested: barefoot jog, rear-foot strike run, fore-foot strike run and fore-foot strike sprint. We conclude that different running ground reaction force-time patterns may have the same mechanical basis.
2021
The current study aimed to evaluate the effects of barefoot and shod running with two different styles on ground reaction force-frequency content in recreational runners with low arched feet. Methods: The statistical sample of this research was 13 males with Pronated Feet (PF) (Mean±SD age: 26.2±2.8 y; height: 176.1±8.4 cm; weight: 78.3±14.3 kg). A force plate (Bertec, USA) with a sample rate of 1000 Hz was used to record the reaction forces under each foot. Three test conditions in our study included shod running with rearfoot, midfoot, and forefoot patterns. Repeated-measures Analysis of Variance (ANOVA) was used for analyzing the data. Results: During forefoot running, the research subjects attained 10% higher GRF values in vertical direction, compared with rearfoot running (P˂0.001, d=2.133). Forefoot running decreased the peak vertical GRF, compared to rearfoot running (by 12%, P=0.01, d=0.826). Barefoot running decreased the peak vertical GRF, compared to shod running (by 6%, P=0.027, d=1.143). The collected results revealed a significantly lower FyMed (P<0.