Dynamic response of human foot and ankle system to vertical vibration (original) (raw)
Related papers
Transmission of Vertical Vibration to the Human Foot and Ankle
Annals of Biomedical Engineering, 2013
The load absorbing capability of the foot and ankle system (FAS) was characterized by measuring the transmissibility and the phase delay at the medial malleolus and the tibial tuberosity. The FAS of twenty subjects were exposed to sinusoidal vertical excitation (10-50 Hz with 5 Hz increments and peak to peak acceleration of 17.9 m/s 2 ) while sitting as a function of the external mass (0, 2.3, and 4.5 kg) and the foot postures (midstance, plantarflexion, and dorsiflexion). The results showed that the FAS plays important role in vibration transmission of lower leg. Adding extra mass affected a resonant frequency at the medial malleolus: 15-25, 30-35, and 35 Hz for with no additional mass, 2.3, and 4.5 kg, respectively. However, the changed postures of the FAS did not show significant effect on the resonant frequency. The applied mass affected the stiffness increase of the FAS and consequently resulted in the increase of the resonant frequency. This result supports the assertion that the resonant frequency of overweight or obese persons is similar to the major frequency component (25-35 Hz) of the heel strike.
Universal Journal of Public Health
The intra-subject variability is evaluated by a deterministic acceleration model in the frequency content between walking and running activities. The usefulness of this research is to explore the dependence of peak acceleration of foot on different pedestrian's velocity. Method: The mathematical model can be represented in time domain as a sum of Fourier harmonic components. The mathematical approach is applied to fit the accelerations of the foot, acquired during the impact shock of the human body on treadmill during walking and running activities at different speeds. Spectral analysis evaluates the frequency field of impact shock during walking and running activities. Results: The fitting of experimental data, by a mathematical approach, offers the analysis of the peak force of the foot on the ground, the dynamic acceleration factor (DAF) and the activity rate harmonics during walking and running activities. Conclusion: Marked differences in vertical accelerations are illustrated between walking and running activities. Recommendations could be deducted with regard to the dose of impacts that can be beneficial or detrimental to human health.
Natural Shock Absorption of the Leg Spring
Journal of Biomechanics, 2012
When a human being runs, muscles, tendons, and ligaments together behave like a single linear spring. This ''leg spring'' can be described remarkably well by spring/mass models. Although leg-stiffness during running (and logically, therefore, in hopping) has been shown to be adjusted in line with the individual characteristics of the external contact surface, the relative contribution of each of the subcomponents of the leg spring to the mechanics of running is unclear.
Impact shock frequency components and attenuation in rearfoot and forefoot running
Journal of Sport and Health Science, 2014
Background: The forefoot running footfall pattern has been suggested to reduce the risk of developing running related overuse injuries due to a reduction of impact related variables compared with the rearfoot running footfall pattern. However, only time-domain impact variables have been compared between footfall patterns. The frequency content of the impact shock and the degree to which it is attenuated may be of greater importance for injury risk and prevention than time-domain variables. Therefore, the purpose of this study was to determine the differences in head and tibial acceleration signal power and shock attenuation between rearfoot and forefoot running. Methods: Nineteen habitual rearfoot runners and 19 habitual forefoot runners ran on a treadmill at 3.5 m/s using their preferred footfall patterns while tibial and head acceleration data were collected. The magnitude of the first and second head acceleration peaks, and peak positive tibial acceleration were calculated. The power spectral density of each signal was calculated to transform the head and tibial accelerations in the frequency domain. Shock attenuation was calculated by a transfer function of the head signal relative to the tibia. Results: Peak positive tibial acceleration and signal power in the lower and higher ranges were significantly greater during rearfoot than forefoot running (p < 0.05). The first and second head acceleration peaks and head signal power were not statistically different between patterns (p > 0.05). Rearfoot running resulted in significantly greater shock attenuation for the lower and higher frequency ranges as a result of greater tibial acceleration (p < 0.05). Conclusion: The difference in impact shock frequency content between footfall patterns suggests that the primary mechanisms for attenuation may differ. The relationship between shock attenuation mechanisms and injury is not clear but given the differences in impact frequency content, neither footfall pattern may be more beneficial for injury, rather the type of injury sustained may vary with footfall pattern preference.
Dose-Response
The aim of this study was to characterize acceleration transmission and neuromuscular responses to rotational vibration (RV) and vertical vibration (VV) at different frequencies and amplitudes. Methods: Twelve healthy males completed 2 experimental trials (RV vs VV) during which vibration was delivered during either squatting (30 ; RV vs VV) or standing (RV only) with 20, 25, and 30 Hz, at 1.5 and 3.0 mm peak-to-peak amplitude. Vibrationinduced accelerations were assessed with triaxial accelerometers mounted on the platform and bony landmarks at ankle, knee, and lumbar spine. Results: At all frequency/amplitude combinations, accelerations at the ankle were greater during RV (all P < .03) with the greatest difference observed at 30 Hz, 1.5 mm. Transmission of RV was also influenced by body posture (standing vs squatting, P < .03). Irrespective of vibration type, vibration transmission to all skeletal sites was generally greater at higher amplitudes but not at higher frequencies, especially above the ankle joint. Acceleration at the lumbar spine increased with greater vibration amplitude but not frequency and was highest with RV during standing. Conclusions/Implications: The transmission of vibration during whole-body vibration (WBV) is dependent on intensity and direction of vibration as well as body posture. For targeted mechanical loading at the lumbar spine, RV of higher amplitude and lower frequency vibration while standing is recommended. These results will assist with the prescription of WBV to achieve desired levels of mechanical loading at specific sites in the human body.
Vibration transmission to lower extremity soft tissues during whole-body vibration
Journal of Biomechanics, 2014
In order to evaluate potential risks of whole-body vibration (WBV) training, it is important to understand the transfer of vibrations from the WBV platform to the muscles. Therefore, the purpose of this study was to quantify the transmissibility of vibrations from the WBV platform to the triceps surae and quadriceps soft tissue compartments.
How human musculoskeletal system deals with the heel strike initiated shock waves
2016
The objective for this work was to investigate how the human musculoskeletal system deals with propagation and attenuation of the shock wave initiated at the heel strike. An experiment was designed to evaluate amplitude of the shock wave arriving at both tibial tuberosities and forehead due to the heel strike. By analyzing data collected from the experiments, this work aimed to find how the human body could attenuate the heel strike initiated shock waves and to protect the head from overloading. 10 young healthy volunteers participated in this study. Each subject was walking and running on the treadmill at four different progressive speeds for 30 seconds at each speed. The heel strike induced shock waves were recorded by externally attached accelerometers on both tibial tuberosities and forehead. The data analysis reveals that the heel strike induced shock waves recorded on both tibial tuberosities and forehead increases when the walking or running speed increases. However, the hee...
Transmission of Vertical Whole Body Vibration to the Human Body
2000
According to experimental studies, low-amplitude high-frequency vibration is anabolic to bone tissue, whereas in clinical trials, the bone effects have varied. Given the potential of whole body vibration in bone training, this study aimed at exploring the transmission of vertical sinusoidal vibration to the human body over a wide range of applicable amplitudes (from 0.05 to 3 mm) and frequencies
PLoS ONE, 2013
Increased muscle activation during whole-body vibration (WBV) is mainly ascribed to a complex spinal and supraspinal neurophysiological mechanism termed the tonic vibration reflex (TVR). However, TVR has not been experimentally demonstrated during low-frequency WBV, therefore this investigation aimed to determine the expression of TVR during WBV. Whilst seated, eight healthy males were exposed to either vertical WBV applied to the leg via the plantar-surface of the foot, or Achilles tendon vibration (ATV) at 25Hz and 50Hzfor 70s. Ankle plantarflexion force, tri-axial accelerations at the shank and vibration source, and surface EMG activity of m. soleus (SOL) and m. tibialis anterior (TA) were recorded from the unloaded and passively loaded leg to simulate body mass supported during standing. Plantar flexion force was similarly augmented by WBV and ATV and increased over time in a load-and frequency dependent fashion. SOL and TA EMG amplitudes increased over time in all conditions independently of vibration mode. 50Hz WBV and ATV resulted in greater muscle activation than 25Hz in SOL when the shank was loaded and in TA when the shank was unloaded despite the greater transmission of vertical acceleration from source to shank with 25Hz and WBV, especially during loading. Low-amplitude WBV of the unloaded and passively loaded leg produced slow tonic muscle contraction and plantar-flexion force increase of similar magnitudes to those induced by Achilles tendon vibration at the same frequencies. This study provides the first experimental evidence supporting the TVR as a plausible mechanism underlying the neuromuscular response to whole-body vibration.