Viscoelastic Insoles Research Articles

Efecto de las botas de bombero y las plantillas viscoelásticas sobre la fuerza de impacto de la componente vertical de la fuerza de reacción del suelo

Objetivos: determinar el efecto de las botas de bombero sobre la componente vertical de la fuerza de reacción del suelo (FRS), en el contacto inicial del talón en el suelo o también denominada fuerza de impacto, así como analizar el efecto de las plantillas viscoelásticas implantadas en las botas de bombero sobre esta fuerza durante la marcha. Metodología: Se registró la magnitud de la fuerza de impacto (FZI) de la componente vertical de la FRS, el tiempo hasta la producción de esta fuerza (TZI) y su gradiente de carga (GC); 39 bomberos sin ningún tipo de patología durante los dos años previos a la toma de registros formaron parte del estudio. Se comparó la marcha en tres condiciones diferentes de calzado: 1) la marcha con botas de bombero, 2) la marcha con botas de bombero a las cuales se les había implantado unas plantillas viscoelásticas y 3) la marcha con calzado deportivo. Resultados: mostraron una mayor producción, así como una mayor magnitud de la fuerza de impacto con botas de bombero respecto a la marcha con calzado deportivo (13,1 vs. 2,6 % de producción de la fuerza de impacto y 61,39 ± 35,18% PC (peso corporal) vs. 49,38 ± 22,99% PC, respectivamente). La marcha con plantillas viscoelásticas implantadas en las botas de bombero no mostró diferencias significativas en ningún parámetro que caracteriza la fuerza de impacto respecto a la marcha sin plantillas. Conclusiones: los resultados de este estudio muestran por un lado, una menor amortiguación de la fuerza de impacto con las botas de bombero en comparación con la marcha con calzado deportivo y por otro, la ineficacia de las plantillas viscoelásticas implantadas en las botas de bombero para la mejora de la amortiguación de la fuerza de impacto durante la marcha a velocidad espontánea.

Venous Insufficiency and Foot Dysmorphism: Effectiveness of Visco-Elastic Rehabilitation Systems on Veno-Muscle System of the Foot and of the Calf

Chronic venous disease is very common and widespread. Chronic Venous Insufficiency (CVI) is a condition characterized by hypertension of the venous system of the lower limbs which manifests itself through a large range of symptoms. The main cause of CVI is hypertension of the venous system of lower limbs, which in most cases is due to reflux for the incontinence of the valvar system of veins. Other causes are related to obstruction of the venous outflow, or at a reduced venous emptying due to inefficiency of the system of the veno-muscular pumps of the calf and of the foot. The purpose of this study was to evaluate if the use of a non-invasive rehabilitative mode to improve the efficiency of the veno-muscular pumps of the foot and of the calf using photoplethysmography in reflected light. Fifty (50) patients suffering from flatfoot and ped cavus, were studied doing a stabilometric and baropodometric test to evaluate the angle of the foot and the podalic angle. Patients were evaluated by examining vascular examination and venous reography in basal condition, using corrective visco-elastic insoles for the correction of dysmorphisms that we were studying. An improvement of the angle of the Right and Left axis (p<0.05) and the podalic angle (p<0.001), using the right insole both in the flatfoot and cavus foot, was shown by the podobarographic examination. A not important tendency to improvement was also shown by the use of non-specific insole in both pathologies. The vascular examination showed an improvement of 38 percent in venous emptying capacity of the foot/calf veno-muscular pump in cavus foot with the specific B insole (p<0.002). An important improvement of 24 percent, using the specific A insole (p<0.05), was documented in flatfoot. The photoplethysmography examination documented a significant improvement of the venous emptying capacity of foot-calf veno-muscular system due to the use of specific insoles for the studied dysmorphism, with an improving tendency even with the use of non-specific insoles. The hemodynamic improvement is correlated with the improvement of the analyzed biomechanical parameters: contact time, lenght of the halfstep, podalic angle and angle of the foot. The partial normalization of biomechanical parameters allows a reorganization of relationships of forces between ground and foot, as well as the improvement of the function of the subtalar joint, causing a partial recovery of the complex physiological mechanism of activation of the veno-muscular pumps of the foot and of the calf.

Wear and Biomechanical Characteristics of a Novel Shear-Reducing Insole with Implications for High-Risk Persons with Diabetes

This study was designed to measure pressure and shear reduction of a novel insole design. We compared three multilayer viscoelastic insoles to a novel insole design (Glide-Soft, Xilas Medical, Inc., San Antonio, TX). The bottom pad of each insole was fabricated from firm-density Plastazote [Apex Foot Products (now Aetrex), South Hackensack, NJ] with an upper of Plastazote, ethyl vinyl acetate, or PORON (Langer Biomechanics Group, Inc., Deer Park, NY). The GlideSoft design used the same materials with two intervening thin sheets of a low friction material. We measured foot pressures, shear, and material stiffness prospectively as the insoles aged during daily usage in 30 healthy adults. We used the F-Scan (Tekscan, Inc., Boston, MA) to determine in-shoe foot pressures and the Automated Stress-relaxation Creep Indenter System (Xilas Medical) to measure material stiffness. To evaluate shear force, the insole was placed on the slide assembly of a custom-designed shear tester equipped with a reciprocating mechanism and force transducers. The GlideSoft exhibited 57% less peak shear force than the standard insole (P < 0.05) in laboratory testing under simulated conditions. Ethyl vinyl acetate had higher compressive stiffness values than Plastazote and PORON at all test intervals (P < 0.05). There were no statistical differences between any of the insoles for peak in-shoe pressure measurements (P > 0.05). The GlideSoft design demonstrated a significant reduction in shear while maintaining equivalent pressure reduction compared with standard insole designs with three different material combinations for up to 320,000 steps.

Biomechanical evaluation and management of the shock waves resulting from the high-heel gait: I — temporal domain study

Abstract This work analysed dynamic loading on the human musculoskeletal system while walking in high-heel-shoes. The effects of viscoelastic shoe shock absorbers on attenuation and dissipation of the high-heel-shoe-generated shock waves were also analysed. The results showed that heels higher than 12 mm actually increase the magnitude of the heel and metatarsal strike-initiated shock waves. Use of viscoelastic shoe insoles can reduce their amplitudes by as much as 29% for the 75-mm-high heel. The described methodology can be used for non-invasive, in-vivo evaluation of the shock absorbing capacity of a various high-heel shoes and viscoelastic insoles and heel plugs during walking. The main advantage of the presented technique is its capacity to account for a foot-heel plug or shoe insole interaction. The results of this study show that walking in high-heel shoes significantly increases the dynamic loading on the human musculoskeletal system, and that viscoelastic shock-absorbing devices can reduce this loading.

Biomechanics of stair walking and jumping

Physical activities such as stair walking and jumping result in increased dynamic loading on the human musculoskeletal system. Use of light weight, externally attached accelerometers allows for in-vivo monitoring of the shock waves invading the human musculoskeletal system during those activities. Shock waves were measured in four subjects performing stair walking up and down, jumping in place and jumping off a fixed elevation. The results obtained show that walking down a staircase induced shock waves with amplitude of 130% of that observed in walking up stairs and 250% of the shock waves experienced in level gait. The jumping test revealed levels of the shock waves nearly eight times higher than that in level walking. It was also shown that the shock waves invading the human musculoskeletal system may be generated not only by the heel strike, but also by the metatarsal strike. To moderate the risk of degenerative joint disorders four types of viscoelastic insoles were utilized to reduce the impact generated shock waves. The insoles investigated were able to reduce the amplitude of the shock wave by between 9% and 41% depending on the insole type and particular physical activity. The insoles were more effective in the reduction of the heel strike impacts than in the reduction of the metatarsal strike impacts. In all instances, the shock attenuation capacities of the insoles tested were greater in the jumping trials than in the stair walking studies. The insoles were ranked in three groups on the basis of their shock absorbing capacity.

Dynamic loading on flamenco dancers: A biomechanical study

The Flamenco dancer acts on the floor like a drummer. The percussive footwork during dancing generates a series of shock waves which impose unusual demands on the musculoskeletal system. This study investigated biomechanical aspects of this task and ways to reduce the amplitude of the shock waves by the in-shoe viscoelastic insoles. Using skin-mounted accelerometers, hip and knee vibrations were recorded in three female dancers. The recorded acceleration data reveal the percussive nature of the dance. Urogenital disorders, as well as back and neck pain, may be related to the shock waves generated by the Flamenco dance form. Use of the insoles seems to reduce the amplitude of dynamic loading recorded on the tibial tuberosity of the dancer by 9–29% depending on the dance and performer. Evaluation of the shock waves invading the human musculoskeletal system during Flamenco dancing is suggested as a useful tool for evaluating dancers' biomechanical behavior, as well as the effect of the floors and footwear on the dynamic loading of dancers' musculoskeletal system.

Viscoelastic Shoe Insoles: Their Use in Aerobic Dancing

To determine whether use of viscoelastic insoles would significantly decrease the frequency of musculoskeletal overuse injury in aerobic dancers, 139 high-level aerobic dancers were divided randomly into two groups. The control group received placebo foam insoles and test subjects were fitted with viscoelastic insoles. Subjects used these insoles during dance class for 15 weeks. Injury rates were low in both groups and no statistical difference was found. Pain syndromes were fewer in the group using viscoelastic insoles, but the difference was not statistically significant. About a third of dancers fitted with viscoelastic insoles and a tenth of placebo insert wearers found that the insoles made their shoes too tight to be comfortable. No conclusion can be drawn on whether shock-absorbing insoles decrease injuries from aerobic dancing, but use of viscoelastic insoles may improve comfort and provide pain relief for some high-level aerobic dancers if proper fit is achieved.