The Variation of Plantar Temperature and Plantar Pressure during Shod Running with Socks or not

Influence of changes in foot morphology and temperature on bruised toenail injury risk during running

Despite runners frequently suffering from dermatologic issues during long distance running, there is no compelling evidence quantitatively investigating their underlying injury mechanism. This study aimed to determine the foot morphology and temperature changes during long distance running and reveal the effect of these alterations on the injury risk of bruised toenail by measuring the subjective-perceived hallux comfort and gap length between the hallux and toebox of the shoe. Ten recreational runners participated in the experimental tests before (baseline), immediately after 5 and 10 km of treadmill running (12 km/h), in which the foot morphology was measured by a 3D foot scanner, the foot temperature was detected by an infrared camera, the perceived comfort was recorded by a visual analogue scale, and the gap length in the sagittal plane was captured by a high-speed camera. Ball width became narrower (106.39 ± 6.55 mm) and arch height (12.20 ± 2.34 mm) was reduced greatly after the 10 km run (p < 0.05). Foot temperature increased significantly after 5 and 10 km of running, and the temperature of dorsal hallux (35.12 ± 1.46 °C), dorsal metatarsal (35.92 ± 1.59 °C), and medial plantar metatarsal (37.26 ± 1.34 °C) regions continued to increase greatly from 5 to 10 km of running (p < 0.05). Regarding hallux comfort, the perceived scores significantly reduced after 5 and 10 km of running (2.10 ± 0.99, p < 0.05). In addition, during one running gait cycle, there was a significant increase in gap length at initial contact (39.56 ± 6.45 mm, p < 0.05) for a 10 km run, followed by a notable decrease upon reaching midstance (29.28 ± 6.81 mm, p < 0.05). It is concluded that the reduced ball width and arch height while increased foot temperature during long-distance running would exacerbate foot-shoe interaction, potentially responsible for bruised toenail injuries.

Finite element modelling for footwear design and evaluation: A systematic scoping review

Finite element modelling has become an efficient tool for an in-depth understanding of the foot, footwear biomechanics and footwear optimization. The aim of this paper was to provide an updated overview in relation to the footwear finite element (FE) analysis published since 2000. The paper will attempt to outline the main challenges and research gaps that need confronting in the further development of realistic and accurate models for clinical and industrial applications. English databases of the Web of Science and PubMed were used to search (‘finite element’ OR ‘FEA’ OR ‘computational model’) AND (‘shoe’ OR ‘footwear’) until 16 December 2021. Articles that conducted FE analyses on the whole foot and footwear structures were included in this review. Twelve articles met the eligibility criteria, and were grouped into three categories for further analysis, (1) finite element modelling of the foot and high-heeled shoes; (2) finite element modelling of the foot and boot; (3) finite element modelling of the foot and sports shoe. Even though most of the existing foot-shoe FE analyses were performed under certain simplifications and assumptions, they have provided essential contributions in identifying the mechanical response of the foot in casual or athletic footwear. Further to this, the results have provided information in relation to optimizing footwear design to enhance functional performance. Nevertheless, further simulations still present several challenges, including reliable data information for geometry reconstruction, the balance between accurate details and computational cost, accurate representations of material properties, realistic boundary and loading conditions, and thorough model validation. In addition, some research gaps in terms of the coverage of footwear design, the consideration of insole/orthosis and socks, and the internal and external validity of the FE design should be fully covered.

Development of a self-monitoring tool for diabetic foot prevention using smartphone-based thermography: Plantar thermal pattern changes and usability in the home environment

Thermography is a well-known risk-assessment tool for diabetic foot ulcers but is not widely used in the home setting due to the influence of the complicated home environment on thermographic images. This study investigated changes in thermographic images in complicated home environments to determine the feasibility of smartphone-based thermography in home settings. Healthy volunteers (age > 20 years) were recruited and required to take plantar thermal images using smartphone-based thermography attached to a selfie stick at different times of the day for 4 days. The thermal images and associated activities and environmental factors were then analyzed using content analysis. Areas with the highest temperature on the plantar thermal images were described and categorized. Device usability was evaluated using 10-point Likert scales, with 10 representing the highest satisfaction. A total of 140 plantar thermal images from 10 participants were analyzed. In 12 classifications, the three commonest patterns based on the highest temperature location were medial arch (42.1%), whole plantar (10.7%), and forefoot and medial arch (7.9%). The medial arch pattern is most frequently seen after awakening (67.5%) compared to other time points. Device usability was rated 7.5 out of 10 on average. This study was the first to investigate the plantar thermal patterns in the home settings, and the medial arch pattern was the most common hot area, which matches previous findings in well-controlled clinical settings. Therefore, smartphone-based thermography may be feasible as a self-assessment tool in the home setting.

Footwear outsole temperature may be more related to plantar pressure during a prolonged run than foot temperature

Objective. The temperature of the sole of the foot has been suggested as an alternative to the measurement of plantar pressure during running despite the scarce evidence about their relationship. The temperature of the footwear outsole could also be representative of plantar pressure distribution due to its less multifactorial dependence. The aim of the study was to determine if plantar pressure during a prolonged run could be related to plantar temperature, either of the sole of the foot or the footwear outsole.Approach. Thirty recreational runners (15 males and 15 females) performed a 30 min running test on a treadmill. Thermographic images of the sole of the foot and the footwear outsole were taken before and immediately after the test, and dynamic plantar pressure was measured at the end of the test. Pearson correlations and stepwise multiple linear regressions were performed.Main results.Plantar pressure percentage was related to a moderate correlation with plantar temperature percentage in forefoot and rearfoot (P < 0.05), showing a greater relationship with the footwear outsole than with the sole of the foot (r = 0.52-0.73 versusr = 0.40-0.61, respectively). Moreover, moderate correlations were also observed between footwear outsole and sole of the foot temperature variables, especially in rearfoot.Significance. Footwear outsole temperature may be better related to plantar pressure distribution than sole of the foot temperature, in the forefoot and rearfoot. The midfoot is the most sensitive and variable region to analyze, as it does not seem to have any relationship with plantar pressure.