plantar pressure
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The use of minimalist shoes (MS) in running involves changes in running mechanics compared to conventional shoes (CS), but there is still little research analysing the effects of this footwear on plantar pressure, which could help to understand some risk injury factors. Moreover, there are no studies examining the effects of a prolonged running and foot strike patterns on baropodometric variables in MS. Therefore, the aim of this study was to analyse the changes produced using MS on plantar pressure during a prolonged running, as well as its interaction with the time and foot strike pattern. Twenty-one experienced minimalist runners (age 38 ± 10 years, MS running experience 2 ± 1 years) ran with MS and CS for 30 min at 80% of their maximal aerobic speed, and mean pressure, peak pressure, contact time, centre of pressure velocity, relative force and contact area were analysed using a pressure platform. Foot strike pattern and time were also considered as factors. The multivariable linear regression mixed models showed that the use of MS induced, at the end of a prolonged running, higher peak pressure (p = 0.008), lower contact time (p = 0.004) and lower contact area (p < 0.001) than using CS. Also, runners with forefoot strike pattern using MS, compared to midfoot and rearfoot patterns, showed higher mean and peak pressure (p < 0.001) and lower contact time and area (p < 0.05). These results should be considered when planning training for runners using MS, as higher peak pressure values when using this type of footwear could be a risk factor for the development of some foot injuries.

Footprint recognition and parameter measurement are widely used in fields like medicine, sports, and criminal investigation. Some results have been achieved in the analysis of plantar pressure image features based on image processing. But the common algorithms of image feature extraction often depend on computer processing power and massive datasets. Focusing on the auxiliary diagnosis and treatment of foot rehabilitation of foot laceration patients, this paper explores the image feature analysis and dynamic measurement of plantar pressure based on fusion feature extraction. Firstly, the authors detailed the idea of extracting image features with a fusion algorithm, which integrates wavelet transform and histogram of oriented gradients (HOG) descriptor. Next, the plantar parameters were calculated based on plantar pressure images, and the measurement steps of plantar parameters were given. Finally, the feature extraction effect of the proposed algorithm was verified, and the measured results on plantar parameters were obtained through experiments.

Anterior cruciate ligament (ACL) lesion represents one of the most dramatic sport injuries. Even though clinical screenings aiming at identifying subjects at risk of injuries are gaining popularity, the use of sophisticated equipment still represents a barrier towards their widespread use. This study aimed to test both reliability and repeatability of a new methodology to assess lower limb joints kinematics and kinetics directly on field with the aid of video cameras and plantar pressure insoles. Ten athletes and one case study (post ACL surgery) were assessed in a gait laboratory, while performing double leg squats, through the simultaneous acquisition of stereophotogrammetry, force plates, commercial video cameras and plantar pressure insoles. Different sources of errors were investigated and both reliability and repeatability analysis performed. Minimum and maximum RMSE values of 0.74% (right knee joint center trajectory) and 64.51%, respectively (ankle dorsi-plantarflexion moment), were detected. Excellent to good correlation was found for the majority of the measures, even though very poor and inverse between-trials correlation was found on a restricted number of trials especially for the ankle dorsi-plantarflexion moment. These findings could be used in combination with already available screening tools in order to provide more repeatable results.

A method for estimating ground reaction force (GRF) with plantar pressure was proposed in this paper. The estimation model was constructed to approximate the nonlinear relationships between GRF and the plantar pressure according to the linear combinations of Gaussian kernel functions. Partial least squares regression (PLSR) was adopted to obtain model parameters and eliminate multicollinearity among the pressure components. The general model and subject-specific models were constructed for 12 male and 4 female subjects. Moreover, a data expansion method was introduced for the establishment of subject-specific model, which is implemented by searching and adopting the data with consistent statistical characteristics in a pre-established database. That approach is particularly meaningful for the group whose walking ability is limited or clinic where the force platform is not available. The NRMSEs (%) for general model were 5.27–7.85% (GRF_V), 7.35–8.53% (GRF_ML), and 8.82–10.54% (GRF_AP). The maximum NRMSEs (%) for subject-specific models were 5.02% (GRF_V), 9.91% (GRF_ML), and 10.23% (GRF_AP). Results showed that both general and subject-specific models achieved higher accuracy than existing methods such as linear regression and neural network methods.

Background: A better understanding of plantar pressure while standing and walking would help in improving balance and gait performance across different age ranges. Objective: To clarify the differences of plantar pressure while standing and walking among children, adults, and the elderly. Materials and Methods: Fifty-three participants including eleven aged 3 to 8 years, thirty aged 20 to 40 years, and twelve aged 60 to 90 years were included in the present study. Plantar pressure and related parameters while quiet standing and walking with self-selected speed were assessed. Results: In static plantar pressure, no significant differences were observed of mean different pressure and mean different contact area between dominant and non-dominant limbs among the three groups, while center of pressure (COP) displacement was shown as significantly greater between children and adults (p<0.05). For dynamic plantar pressure, no significant differences in COP velocity were found among the three groups. The elderly showed significant lower normalized maximum plantar pressure in areas of the second and third metatarsal, and internal heel compared with the young adults (p<0.05). Additionally, normalized maximum plantar pressures among children seemed to differ from adults. Conclusion: Plantar pressure characteristics could indicate that children develop gait ability in braking and propulsion phases with greater heel and toe function, while the ability of braking and propulsion declined with aging. These could reflect balance ability while standing or walking. Keywords: Foot pressure; Children; Elderly; Normalization

Among people with diabetes mellitus (DM), the two common strategies for decreasing peak plantar pressure (PPP) to reduce diabetic foot ulcers (DFUs) risks are to modify walking speeds and to change insole materials. This study reviewed the PPP reduction based on various walking speeds and insole materials. The articles were retrieved from four major scientific databases and manual search. We identified 1585 articles, of which 27 articles were selected for full-text analysis. We found that in faster walking speeds, the forefoot PPP was higher (308 kPa) than midfoot (150 kPa) and rearfoot (251 kPa) PPP. The appropriate walking speed for reducing the forefoot PPP was about 6 km/h for non-DM and 4 km/h for DM people. The forefoot PPP in DM people was 185% higher than that of non-DM people. Ethylene–vinyl acetate (EVA) insole material was the most popular material used by experts (26%) in the forefoot and reduced 37% of PPP. In conclusion, the suitable walking speed for DM was slower than for non-DM people, and EVA was the most common insole material used to decrease the PPP under the forefoot. The clinicians might recommend DM people to walk at 4 km/h and wear EVA insole material to minimize the DFUs.

Background: Plantar fasciopathy (PF) is usually related to changes in foot arch, foot shape and rearfoot posture. However, little research has been implemented by using large-scale datasets, and even less has been conducted centering on plantar pressure distributions (PPDs) of different genders of PF athletes. This study aimed to investigate the relationships among the arch index (AI), the PPDs and the rearfoot postural alignment in hundreds of college athletes with PF during static standing and walking. Methods: Cross-sectional study of 100 male and 102 female athletes with PF was undertaken. The PF athletes’ pain assessment and self-reported health status were examined for evaluating their musculoskeletal painful areas. Results: The PF athletes’ PPDs mainly concentrated on inner feet in static standing, and transferred to lateral forefeet during the midstance phase of walking. The males’ PPDs from the static standing to the midstance phase of walking mainly transferred to anterolateral feet. The females’ PPDs mainly transferred to posterolateral feet. The PF athletes’ static rearfoot alignment matched the valgus posture pattern. The medial band of plantar fascia and calcaneus were the common musculoskeletal pain areas. Conclusions: Characteristics of higher plantar loads beneath medial feet associated with rearfoot valgus in bipedal static stance could be the traceable features for PF-related foot diagrams. Higher plantar loads mainly exerted on the lateral forefoot during the midstance phase of walking, and specifically concentrated on outer feet during the transition from static to dynamic state. Pain profiles seem to echo PPDs, which could function as the traceable beginning for the possible link among pronated low-arched feet, PF, metatarsalgia, calcanitis and Achilles tendinitis.

Diabetic foot syndrome refers to heterogeneous clinical and biomechanical profiles, which render predictive models unsatisfactory. A valuable contribution may derive from identification and descriptive analysis of well-defined subgroups of patients. Clinics, biology, function, gait analysis, and plantar pressure variables were assessed in 78 patients with diabetes. In 15 of them, the 3D architecture of the foot bones was characterized by using weight-bearing CT. Patients were grouped by diabetes type (T1, T2), presence (DN) or absence (DNN) of neuropathy, and obesity. Glycated hemoglobin (HbA1c) and plantar lesions were monitored during a 48-month follow-up. Statistical analysis showed significant differences between the groups for at least one clinical (combined neuropathy score, disease duration, HbA1c), biological (age, BMI), functional (joint mobility, foot alignment), or biomechanical (regional peak pressure, pressure-time integral, cadence, velocity) variable. Twelve patients ulcerated during follow-up (22 lesions in total), distributed in all groups but not in the DNN T2 non-obese group. These showed biomechanical alterations, not always occurring at the site of lesion, and HbA1c and neuropathy scores higher than the expected range. Three of them, who also had weight-bearing CT analysis, showed >40% of architecture parameters outside the 95%CI. Appropriate grouping and profiling of patients based on multi-instrumental clinical and biomechanical analysis may help improve prediction modelling and management of diabetic foot syndrome.