The interaction effect of different footwear types and static navicular drop or dynamic ankle pronation on the joint stiffness of the lower limb during running

BACKGROUND

Although the effects of footwear type on joint stiffness have previously been investigated, researchers did not consider foot flexibility. Thus, the present investigation aimed to determine the interaction effects of footwear type, static navicular drop and dynamic ankle pronation on dynamic joint stiffness in running.

RESEARCH QUESTION

Does the footwear types in interaction with the foot posture affect the stiffness of the joints of the lower limb?

METHODS

Forty-seven male individuals participated in this study. Firstly, they were divided into the high navicular, low navicular, and normal navicular drop. Secondly, they were divided into the high dynamic ankle pronation, low dynamic ankle pronation, and normal dynamic ankle pronation groups. Participants performed three running trials at 3 ± 0.2 m/s at minimalist footwear, conventional footwear, and barefoot conditions. We collected the ground reaction forces and three-dimensional kinematic data and calculated joint stiffness over the stance phase.

RESULTS

There was no significant main effect of navicular drop or dynamic ankle pronation on dynamic joint stiffness for the ankle, knee, and hip (p > 0.05). However, footwear type significantly affected dynamic joint stiffness. The pairwise comparison revealed that the ankle and hip dynamic joint stiffness magnitudes in the conventional footwear condition were greater than in the barefoot and minimalist footwear conditions (p 0.001). In contrast, the knee dynamic joint stiffness magnitude in the conventional footwear condition was lesser than in barefoot and minimalist footwear conditions (p 0.001).

SIGNIFICANCE

The navicular drop or dynamic ankle pronation did not influence lower limb joint stiffness, and there was no significant interaction between navicular drop or dynamic ankle pronation and footwear on lower limb dynamic joint stiffness. However, conventional footwear increased the ankle and hip dynamic joint stiffness while reducing knee dynamic joint stiffness, leading to changes in transfer energy, which could have implications for relative injury risk.

Custom Shoe Sole Design and Modeling Toward 3D Printing

This study introduces a design procedure for improving an individual’s footwear comfort with body weight index and activity requirements by customized three-dimensional (3D)-printed shoe midsole lattice structure. This method guides the selection of customized 3D-printed fabrications incorporating both physical and geometrical properties that meet user demands. The analysis of the lattice effects on minimizing the stress on plantar pressure was performed by initially creating various shoe midsole lattice structures designed. An appropriate common 3D printable material was selected along with validating its viscoelastic properties using finite element analysis. The lattice structure designs were analyzed under various loading conditions to investigate the suitability of the method in fabricating a customized 3D-printed shoe midsole based on the individual’s specifications using a single material with minimum cost, time, and material use.

The impact of standardized footwear on load and load symmetry

BACKGROUND

The inability to standardize footwear is a potential issue when measuring landing kinetics in non-laboratory settings. This study determined the impact of not standardizing footwear on load and load symmetry during landing. A secondary purpose of this study was to introduce the Load Analysis Program, an open-source MATLAB® user-interface for computing kinetic and kinetic symmetry from data collected using loadsol® sensors.

METHODS

Forty uninjured participants completed bilateral and unilateral landing tasks in their own preferred athletic footwear and in laboratory-standardized footwear. Peak impact force, impulse, and a limb symmetry index of both kinetic outcomes were computed using loadsol® sensors (200 Hz) for both footwear conditions, and compared between footwear conditions using intraclass correlation coefficients and Bland-Altman plots.

FINDINGS

The agreement between the preferred and standardized conditions was good to excellent for peak impact force, peak impact force limb symmetry index, and impulse limb symmetry index during the bilateral task (intraclass correlation coefficient = 0.870-0.951). The agreement was moderate to poor for unilateral limb symmetry index measures (intraclass correlation coefficient = 0.399-0.516). During the preferred footwear condition, impulse was greater for the left limb during bilateral landing, and peak impact force during unilateral landing on the right limb was decreased, when compared to the standardized footwear condition (p < 0.05).

INTERPRETATION

These results suggest that while not standardizing footwear can alter the results of certain load metrics, laboratory-relevant landing mechanics information can be obtained with participants wearing their own footwear.

Does running speed affect the response of joint level mechanics in non-rearfoot strike runners to footwear of varying longitudinal bending stiffness?

BACKGROUND

Modifying the longitudinal bending stiffness (LBS) of footwear has become a popular method to improve sport performance. It has been demonstrated to influence running economy by altering lower extremity joint level mechanics. Previous studies have only examined within-participant effects at one running speed.

RESEARCH QUESTION

Do joint level mechanics differ in response to varying footwear LBS at a range of running speeds?

METHODS

This study utilized a cross-sectional repeated measure study design using a convenience sample. Ten well trained non-rearfoot strike male distance runners ran at 3.89, 4.70, and 5.56 m/s (14, 17, 20 km/hr) in footwear of three different LBS levels. Mechanics and energetics of the metatarsophalangeal joint (MTPJ), ankle, knee, and hip joints during stance phase were assessed using an 8-camera optical motion capture system (f_s = 200 Hz), a force instrumented treadmill (f_s = 1000 Hz) and standard inverse dynamics theory.

RESULTS

Range of motion and negative work decreased and angular stiffness increased for the MTPJ with increasing LBS at all speeds (p < .001). Peak MTPJ moment did not change at any speed in response to increased LBS. Negative work at the ankle decreased in the stiff shoe at 17 km/hr (p = .036). Peak ankle plantar flexion velocity decreased with increasing LBS at all speeds (p < .05).

SIGNIFICANCE

While changes in MTPJ mechanics were consistent across speeds, decreased negative ankle work was only observed at 17 km/hr in the stiff shoe, suggesting that perhaps tuned footwear LBS may need to focus primarily on metabolically beneficial changes in ankle plantar flexor mechanical behavior to improve performance in distance runners. Tuning footwear stiffness may also be beneficial to clinical populations, as clinicians seek to optimize their patients' locomotion economy.

Foot structural factors and ground reaction force in hallux valgus grades

BACKGROUND

Little attention has been paid to foot structural factors and ground reaction force in hallux valgus. Investigating the structural factors in detail and determining their biomechanical effects can help to better manage hallux valgus.

METHODS

In this case-control study, 120 females, 90 hallux valgus and 30 healthy, were recruited. Hallux valgus grades (mild, moderate, severe), first metatarsal mobility, foot pronation, hallux rotation, and pain were assessed by clinical tests. Ground reaction forces were measured in barefoot and shod conditions for both feet and analyzed using mixed within-between MANOVA. The association between structural factors and pain with force was analyzed using Spearman correlation coefficient.

RESULTS

The frequency of foot structural factors and pain severity were reported in hallux valgus grades. A significant difference was seen in the force values between groups (P<0.001). Bonferroni post hoc test indicated that the mean of the first peak for the severe group was significantly higher than the mild group (P=0.013) and the mean of second peak for the moderate group was higher than that of the healthy group (P=0.009). The force values were affected by wearing shoe (P<0.001) but not by foot side (P=0.086). There was a medium, positive correlation between the hallux rotation and force in the moderate group (r=0.39, P=0.03) and also between the pronation and force in the severe group (r=0.36, P=0.04).

CONCLUSION

Foot structural factors, pain, and force were different in each hallux valgus grads. Similar force in both feet, and increased force by wearing shoe were seen. The relationship between the pronation and hallux rotation with force revealed the importance of these factors from the biomechanical viewpoint.

Acute responses to barefoot 5 km treadmill running involve changes in landing kinematics and delayed onset muscle soreness

BACKGROUND

Barefoot running has gained popularity among physical activity practitioners, but there is a lack of information regarding the acute adaptations to this running technique without supervision. Information about acute adaptations can help to define the best way to insert barefoot running in the routine of runners willing to, and also provide orientation for those people who want to experience this technique.

RESEARCH QUESTION

What acute adaptations can be observed among recreational runners exposed to barefoot running?

METHODS

Sagittal 2D kinematics, plantar pressure, foot sensitivity and delayed onset muscle soreness were compared between conditions of shod and barefoot running in 13 recreational runners who performed two trials of 5 km treadmill running.

RESULTS

We found an acute effect of barefoot running on foot landing that changes from a rearfoot strike to a forefoot strike pattern. This change most likely contributed to the increase in neuromuscular recruitment of calf muscles (i.e. gastrocnemius and soleus) resulting in higher perception of delayed onset muscle soreness. Barefoot running also elicited higher stride cadence. Plantar pressure before and after running revealed higher pressure in the different foot regions after barefoot running. Foot sensitivity increased after running regardless of the footwear condition.

CONCLUSION

Barefoot running has acute effects on running technique including higher perception of delayed onset muscle soreness in the 48 h following the exercise.

SIGNIFICANCE

Our results highlight the importance of following participants for days after a first session of barefoot running in order to properly manage the acute adaptation periods as well provide precise advices for those trying the barefoot technique.

Electromyography activity of triceps surae and tibialis anterior muscles related to various sports shoes

Triceps surae (TS) and tibialis anterior (TA) activation patterns have not yet been studied under different types of sport shoes. We hypothesized that sports shoes may reduce the activity patterns of these muscles in relation to barefoot condition. Thus, our main aim was to evaluate the activity patterns of TS and TA muscles in healthy people during all gait phases using five types of sport shoes with respect to barefoot condition. A total sample of thirty healthy participants, mean age 36.20 ± 8.50, was recruited in a podiatry laboratory following an observational research design. During walking and running, electromyography signals were recorded from TS and TA muscles using surface electrodes in the following experimental situations: 1.) barefoot, 2.) minimalist, 3.) pronated control, 4.) air chamber, 5.) ethyl-vinyl-acetate and 6.) boost. The TS and TA showed significant reductions (P < 0.05) in the peak amplitude of different sport shoes types with respect to the barefoot condition in different phases of the gait cycle during walking and running. Nevertheless, the boost sport shoe produced statistically significant increases in the peak amplitude of the gastrocnemius medialis muscle in comparison with the barefoot condition in the midstance phase of the gait cycle during running (P = 0.047). In addition, the pronation control and air chamber sport shoes produced statistically significant increases in the peak amplitude of the TA muscle with respect to the barefoot condition in the contact phase of the gait cycle (P = 0.021; P = 0.013), respectively, during running. Despite TS and TA muscles activity patterns seem to be reduced using different sport shoes types with respect to the barefoot condition in different phases of the gait cycle during walking and running, some sport shoes may increase this muscular activity in specific phases of the gait cycle during running.

Effect of lateral wedge length on ambulatory knee kinetics

BACKGROUND

Lateral wedge insoles (LWI) were proposed to treat medial knee osteoarthritis through reductions of the ambulatory knee adduction moment (KAM). Limited attention was however paid to the LWI length, resulting in unclear understanding of its effect on KAM reductions. The knee flexion moment (KFM) was also shown to be important in knee osteoarthritis, but little is known about the effect of LWI length on it.

RESEARCH QUESTION

This study aimed to compare the KAM and KFM of healthy subjects walking with four different lengths of LWI, explicitly without LWI and with LWI below the hindfoot (HF), below the hindfoot and forefoot (HF + FF) and below the hindfoot, forefoot and hallux (HF + FF + HX) segments.

METHODS

Nineteen healthy participants (63% male; 24 ± 3 years old) walked in an instrumented gait lab with LWI of four different lengths. Repeated one-way ANOVAs and post-hoc t-tests were used to compare knee kinetics among LWI lengths.

RESULTS

The peak value of the KAM during the first half of stance and the KAM impulse differed with respect to the LWI length (p < 0.001). A length of at least HF + FF, but not necessarily longer, was needed to decrease both KAM parameters compared to walking without LWI. The LWI length had no effect on the peak value of the KFM during the first half of stance (p = 0.86).

SIGNIFICANCE

The results in this study could contribute to better selections of LWI for medial knee osteoarthritis and suggested that the length of the LWI could be a critical factor that should be considered in future research.

Electromyographic changes in muscles around the ankle and the knee joints in women accustomed to wearing high-heeled or low-heeled shoes

OBJECTIVES

This study aimed to investigate muscle activities in the muscles around the ankle and knee joints in women accustomed to wearing high-heeled or low-heeled shoes.

METHODOLOGY

Forty young women (age: 18-40 years) participated in this comparative clinical study. Twenty of the recruited subjects were accustomed to high-heeled shoes and the other half to low-heeled shoes. Electrical activities of the ankle and knee muscles in both groups with and without wearing their accustomed shoes were studied during walking.

RESULTS

Tibialis anterior and the medial gastrocnemius muscles started contraction earlier in the high-heeled shoe group. The duration of medial gastrocnemius activity and the intensity of proneus longus activity were significantly more in the high-heeled shoe group.

CONCLUSION

Wearing high-heeled shoe for a long time could result in over work of muscles such as medial gastrocnemius and proneus longus by increasing the duration or the intensity of their contractions during walking.

The efficacy of removable devices to offload and heal neuropathic plantar forefoot ulcers in people with diabetes: a single-blinded multicentre randomised controlled trial

Non-removable offloading is the 'gold standard' treatment for neuropathic diabetic plantar forefoot ulcers. However, removable offloading is the common 'standard of care'. We compared three removable offloading devices for ulcer healing efficacy. In this multicentre, randomised controlled trial, 60 persons with neuropathic diabetic plantar forefoot ulcers were randomly assigned to wear a custom-made knee-high cast [BTCC (bivalved TCC)], custom-made ankle-high cast shoe or a prefabricated ankle-high forefoot-offloading shoe (FOS). Primary outcome was healing at 12 weeks. Dynamic plantar pressures, daily stride count and treatment adherence were assessed on a randomly selected subset (n = 35). According to intention-to-treat analysis, 58% of patients healed with BTCC [OR 0·77 (95% CI 0·41-1·45) versus FOS], 60% with cast shoe [OR 0·81 (95% CI 0·44-1·49) versus FOS] and 70% with FOS (P = 0·70). Mean ± SD peak pressure in kPa at the ulcer site was 81 ± 55 for BTCC, 176 ± 80 for cast shoe and 107 ± 52 for FOS (P = 0·005); stride count was 4150 ± 1626, 3514 ± 1380 and 4447 ± 3190, respectively (P = 0·71); percentage of 2-week intervals that patients wore the device <50% of time was 17·3%, 5·2% and 4·9%, respectively. Non-significant differences in healing efficacy between the three devices suggest that, when non-removable offloading is contraindicated or not available, each can be used for plantar forefoot ulcer offloading. Efficacy is lower than previously found for non-removable offloading maybe because suboptimal adherence and high stride count expose the patient to high repetitive stresses. These factors should be carefully considered in decision making regarding ulcer treatment.

Subject Specific Optimisation of the Stiffness of Footwear Material for Maximum Plantar Pressure Reduction

Current selection of cushioning materials for therapeutic footwear and orthoses is based on empirical and anecdotal evidence. The aim of this investigation is to assess the biomechanical properties of carefully selected cushioning materials and to establish the basis for patient-specific material optimisation. For this purpose, bespoke cushioning materials with qualitatively similar mechanical behaviour but different stiffness were produced. Healthy volunteers were asked to stand and walk on materials with varying stiffness and their capacity for pressure reduction was assessed. Mechanical testing using a surrogate heel model was employed to investigate the effect of loading on optimum stiffness. Results indicated that optimising the stiffness of cushioning materials improved pressure reduction during standing and walking by at least 16 and 19% respectively. Moreover, the optimum stiffness was strongly correlated to body mass (BM) and body mass index (BMI), with stiffer materials needed in the case of people with higher BM or BMI. Mechanical testing confirmed that optimum stiffness increases with the magnitude of compressive loading. For the first time, this study provides quantitative data to support the importance of stiffness optimisation in cushioning materials and sets the basis for methods to inform optimum material selection in the clinic.

Immediate and short-term biomechanical adaptation of habitual barefoot runners who start shod running

This study investigated the immediate and short-term effects of minimalist shoes (MS) and traditional running shoes (TRS) on vertical loading rates, foot strike pattern and lower limb kinematics in a group of habitual barefoot runners. Twelve habitual barefoot runners were randomly given a pair of MS or TRS and were asked to run with the prescribed shoes for 1 month. Outcome variables were obtained before, immediate after and 1 month after shoe prescription. Average and instantaneous vertical loading rates at the 1-month follow-up were significantly higher than that at the pre-shod session (P < 0.034, η²_p > 0.474). Foot strike angle in the TRS group was significantly lower than that in the MS group (P = 0.045, η²_p = 0.585). However, there was no significant time nor shoe effect on overstride, knee and ankle excursion (P > 0.061). Habitual barefoot runners appeared to land with a greater impact during shod running and they tended to have a more rearfoot strike pattern while wearing TRS. Lower limb kinematics were comparable before and after shoe prescription. Longer period of follow-up is suggested to further investigate the footwear effect on the running biomechanics in habitual barefoot runners.

Effects of footwear on the knee adduction moment in medial knee osteoarthritis: classification criteria for flat flexible vs stable supportive shoes

OBJECTIVE

To validate simple criteria that distinguish flat flexible from stable supportive walking shoes by comparing their effects on the knee adduction moment (KAM) in people with medial knee osteoarthritis (OA).

DESIGN

This was a cross-sectional biomechanical study. We proposed five criteria to differentiate flat flexible from stable supportive shoes, and selected three pairs of shoes representing each class for biomechanical testing. 28 participants aged ≥50 years with symptomatic medial knee OA underwent gait analysis barefoot and wearing each of the six selected shoes, in random order. Differences in the peak KAM, KAM impulse and peak knee flexion moment (KFM) across test conditions were evaluated with a two-way repeated measures analysis of variance (ANOVA). Immediate changes in walking pain between conditions were also compared.

RESULTS

Increases in KAM from barefoot were lower with each of the three flat flexible shoe styles (peak KAM: 6.1-8.9%; KAM impulse: 2.4-5.1%) compared to their stable supportive counterparts (peak KAM: 11.6-15.1%; KAM impulse 10.5-13.2%). There was a significant main effect for footwear class on peak KAM and KAM impulse, whereby stable supportive shoes increased the KAM significantly more than flat flexible shoes (P < 0.001). There were no differences in the KFM or immediate walking pain between footwear classes.

CONCLUSIONS

Our proposed criteria can be used by researchers and clinicians to select flat flexible shoes for people with medial knee OA to minimise knee loading. Future research should evaluate whether wearing shoes based on these criteria translates to improvements in knee OA symptoms and/or slows structural disease progression.

The feasibility of a modified shoe for multi-segment foot motion analysis: a preliminary study

Background

The majority of multi-segment kinematic foot studies have been limited to barefoot conditions, because shod conditions have the potential for confounding surface-mounted markers. The aim of this study was to investigate whether a shoe modified with a webbed upper can accommodate multi-segment foot marker sets without compromising kinematic measurements under barefoot and shod conditions.

Methods

Thirty participants (15 controls and 15 participants with midfoot pain) underwent gait analysis in two conditions; barefoot and wearing a shoe (shod) in a random order. The shod condition employed a modified shoe (rubber plimsoll) with a webbed upper, allowing skin mounted reflective markers to be visualised through slits in the webbed material. Three dimensional foot kinematics were captured using the Oxford multi-segment foot model whilst participants walked at a self-selected speed.

Results

The foot pain group showed greater hindfoot eversion and less hindfoot dorsiflexion than controls in the barefoot condition and these differences were maintained when measured in the shod condition. Differences between the foot pain and control participants were also observed for walking speed in the barefoot and in the shod conditions. No significant differences between foot pain and control groups were demonstrated at the forefoot in either condition.

Conclusions

Subtle differences between pain and control groups, which were found during barefoot walking are retained when wearing the modified shoe. The novel properties of the modified shoe offers a potential solution for the use of passive infrared based motion analysis for shod applications, for instance to investigate the kinematic effect of foot orthoses.

The influence of footwear on functional outcome after total ankle replacement, ankle arthrodesis, and tibiotalocalcaneal arthrodesis

BACKGROUND

Gait analysis after total ankle replacement and ankle arthrodesis is usually measured barefoot. However, this does not reflect reality. The purpose of this study was to compare patients barefoot and with footwear.

METHODS

We compared 126 patients (total ankle replacement 28, ankle arthrodesis 57, and tibiotalocalcaneal arthrodesis 41) with 35 healthy controls in three conditions (barefoot, standardized running, and rocker bottom shoes). Minimum follow-up was 2 years. We used dynamic pedobarography and a light gate.

MAIN OUTCOME MEASURES

relative midfoot index, forefoot maximal force, walking speed.

FINDINGS

The relative midfoot index decreased in all groups from barefoot to running shoes and again to rocker bottom shoes (p<0.001). The forefoot maximal force increased wearing shoes (p<0.001), but there was no difference between running and rocker bottom shoes. Walking speed increased by 0.06 m/s with footwear (p<0.001). Total ankle replacement and ankle arthrodesis were equal in running shoes but both deviated from healthy controls (total ankle replacement/ankle arthrodesis smaller RMI p=0.07/0.017; increased forefoot maximal force p=0.757/0.862; slower walking speed p<0.001). In rocker bottom shoes, this ranking remained the same except the relative midfoot index merged to similar values. Tibiotalocalcaneal arthrodesis were inferior in both shoes.

INTERPRETATION

Runners are beneficial and the benefit is greater for fusions and replacements. Rocker bottom shoes have little added benefit. Total ankle replacement and ankle arthrodesis were equal but inferior to healthy controls. Tibiotalocalcaneal arthrodesis has an inferior outcome.

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

Background

Stress 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.

Methods

The 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.

Results

The 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).

Conclusions

Despite some limitations, the presented device allows for the reliable determination of bending and torsional stresses at the foot in shoes.

A method to investigate the effect of shoe-hole size on surface marker movement when describing in-shoe joint kinematics using a multi-segment foot model

To investigate in-shoe foot kinematics, holes are often cut in the shoe upper to allow markers to be placed on the skin surface. However, there is currently a lack of understanding as to what is an appropriate size. This study aimed to demonstrate a method to assess whether different diameter holes were large enough to allow free motion of marker wands mounted on the skin surface during walking using a multi-segment foot model. Eighteen participants underwent an analysis of foot kinematics whilst walking barefoot and wearing shoes with different size holes (15 mm, 20mm and 25 mm). The analysis was conducted in two parts; firstly the trajectory of the individual skin-mounted markers were analysed in a 2D ellipse to investigate total displacement of each marker during stance. Secondly, a geometrical analysis was conducted to assess cluster deformation of the hindfoot and midfoot-forefoot segments. Where movement of the markers in the 15 and 20mm conditions were restricted, the marker movement in the 25 mm condition did not exceed the radius at any anatomical location. Despite significant differences in the isotropy index of the medial and lateral calcaneus markers between the 25 mm and barefoot conditions, the differences were due to the effect of footwear on the foot and not a result of the marker wands hitting the shoe upper. In conclusion, the method proposed and results can be used to increase confidence in the representativeness of joint kinematics with respect to in-shoe multi-segment foot motion during walking.