Search

Background: The gait variable minimum toe clearance (MTC) has been investigated concerning trip-related fall research in older adults. However, comparing studies is difficult due to the different methods used to measure MTC and shoe conditions, which may affect agreement. Measurement methods can include using a single virtual point (SVP), multiple virtual points (MVPS), or metatarsal head markers (marker-based). The shoe types used in MTC studies include standard shoes (SS), personal shoes (PS), and barefoot (BF) conditions., Research Question: What is the agreement, inter and intra-rater reliability, and repeatability for the 3 commonly used methods of measuring MTC (SVP, MVPS, marker-based) under the 3 shoe conditions for optical motion capture systems (SS, PS, BF)?, Methods: Twelve healthy young adults (mean [SD] 23.8 [1.9] years,7 males) participated in this observational study. In a randomized order, participants completed 25 walking trials at self-selected normal and slow speeds in SS, PS, and BF conditions while infrared cameras recorded the maker trajectories. Each participant performed a familiarization trial for at least 1 minute before collecting data on each shoe condition. Statistical analyses included Bland-Altman 95 % limits of agreement (LOA) analyses, interclass correlation coefficient (ICC) analyses for inter- and intra-rater reliability, and the repeatability coefficient (RC)., Results: The SVP and MVPS had a tighter 95 % LOA than the marker-based method, particularly under SS and BF conditions. The inter-rater reliability was good to excellent under these shoe conditions. Intra-reliability for all methods under all shoe conditions was excellent (ICC >.90). The RC was very similar for each method, with none exceeding 1.02 cm., Significance: The study provides estimates of the agreement between MTC methods and suggests that only SVP or MVPS produced similar results in SS/BF conditions. Additionally, a "true" change in MTC requires a difference greater than 1.02 cm., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Toe flexor strength is generated primarily by the flexor hallucis longus (FHL) of the extrinsic foot muscles (EFMs) and the plantar intrinsic foot muscles (PIFMs) of the great toe. Toe flexion methods can be broadly classified into toe grip (TG) and toe push-down (TP). Additionally, TP's interphalangeal joint (IPJ) position may influence the FHL and PIFMs activity ratios. This study aimed to elucidate the differences in the muscle activity and muscle activity ratios of the FHL and AbdH during TG, TP with IPJ flexion (TPIF), and TP with IPJ extension (TPIE). Surface electromyography and a custom-made instrument were used to measure the FHL and AbdH muscle activity during TG, TPIF, and TPIE of the great toe in 28 healthy men. The muscle activity and AbdH/FHL muscle activity ratio in the three conditions were statistically compared. The FHL activity was significantly higher during TG and TPIF than during TPIE. The AbdH muscle activity was significantly higher during TPIF and TPIE than that during TG. The AbdH/FHL muscle activity ratio was significantly higher for TPIE, TPIF, and TG in that order. This study showed that the FHL and AbdH muscle activity differed depending on the TG and TP of the great toe, and that the AbdH/FHL muscle activity ratio was different in the IPJ position. These results suggest that selecting a toe flexion method according to the target muscle when measuring and training the great toe flexor strength is important., Competing Interests: Declaration of Competing Interest There are no conflicts of interest regarding this study., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background and Objectives: Injuries involving ankle stability and range of motion are among the most frequent in athletes and in the general population. In response, this study aimed to assess the immediate effects of toe separators on dynamic stability and ankle range of motion in healthy young individuals., Methods: Among the 68 eligible participants, 50 healthy and active subjects completed all trials. The impact of the intervention was evaluated using the Weight Bearing Lunge Test and Y-Test. The control condition performed the tests without toe separators, while the experimental condition performed the tests with toe separators. All participants performed both conditions with a wash-out period of at least 7 days between trials., Results: Statistical analysis revealed no significant differences in dynamic balance ( p  > 0.05) and range of motion ( p  > 0.05) between the two conditions. Additionally, no asymmetries were detected between the lower limbs in both tests ( p  > 0.05)., Conclusions: The results of this pilot study indicate that using toe separators does not have an immediate effect on ankle range of motion and dynamic balance in young, healthy individuals. Future research should consider evaluating intervention programs of longer duration and exploring different populations.

Aims: This study explored the reliability, validity and perceived comfort of a novel thumb pressure measure and calculation of a toe-thumb index to identify their suitability as an adjunct or alternatives to ankle-brachial and toe-brachial indices., Methods and Results: Repeated manual thumb and toe systolic blood pressures were conducted using two raters, over two time points, on 34 healthy participants. Concurrent automated toe, thumb and brachial systolic blood pressures as well as comfort ratings for these measures (using a 10 mm visual analogue scale) were captured once by a research assistant. Automated thumb and brachial measures showed fair correlation (ρ = 0.36, p = 0.03) and a toe-thumb index and toe-brachial index good correlation (ρ = 0.62, p < 0.01). Intraclass correlation coefficients (ICC) identified moderate intra-rater reliability for manual thumb pressures for Rater 1 and 2 (ICC 0.57, 95% CI [0.14, 0.79] and ICC 0.74, 95% CI [0.49, 0.87], respectively), while inter-rater reliability was poor (ICC = 0.16, 95% CI [-0.85, 0.47]). Concurrent validity comparing manual and automated measures for thumb pressure was also poor (ICC -0.05, 95% CI [-1.06, 0.72] and ICC 0.42, 95% CI [-0.16, 0.72] Rater 1 and 2 respectively). Thumb measures were significantly more comfortable than brachial measures (5 mm, p < 0.00)., Conclusion: Thumb systolic pressures are correlated with brachial systolic pressures, with reasonable intra-rater reliability, however, correlation is only fair and measurement error wider than clinically acceptable. Furthermore, manual measures are poorly correlated with automated units. Consequently, caution is required in applying these techniques. As thumb measures were perceived as significantly more comfortable than brachial measures and have an advantage where brachial pressures cannot, or should not, be obtained, further evaluation is warranted., (© 2024 The Author(s). Journal of Foot and Ankle Research published by John Wiley & Sons Australia, Ltd on behalf of Australian Podiatry Association and The Royal College of Podiatry.)

Chatogekko amazonicus is a miniaturized gecko from northern South America and is among the smallest of toe pad bearing lizards. The toe pads of C. amazonicus are miniscule, between 18% and 27% of the plantar surface area. We aimed to investigate the relationship between adhesive toe pad morphology, body size, and adhesive capabilities. Using scanning electron microscopy, we determine that the adhesive pads of C. amazonicus exhibit branched setae similar to those of other geckos, but that are generally much smaller. When compared with other gecko taxa, we show that C. amazonicus setae occupy a similar range of seta length: snout-vent length ratio and aspect ratio as other gekkonoid species (i.e. Gekkonidae, Phyllodactylidae, and Sphaerodactylidae). We demonstrate that C. amazonicus-even with its relatively small toe pads-is capable of climbing a smooth glass surface at a nearly vertical angle. We suggest that sphaerodactylids like C. amazonicus offer an excellent system for studying toe pad morphology and function in relation to miniaturization., (© 2024 The Author(s). The Anatomical Record published by Wiley Periodicals LLC on behalf of American Association for Anatomy.)

This research introduces an adaptive control algorithm designed to determine gait phase in real-time using an inertial measurement unit (IMU) affixed to the shank. Focusing on detecting specific gait events, primarily initial contact (IC) and toe-off (TO), the algorithm utilizes dynamic thresholds and ratios that facilitate accurate event determination adaptively across a range of walking speeds. Built-in safety checks further ensure precision and minimize false detections. We validated the algorithm with eight participants walking at varying speeds. The algorithm demonstrated promising results in detecting IC and TO events with mean lead of 8.95 ms and 4.42 ms and detection success rate of 100% and 99.72%, respectively. These results are consistent with benchmarks from established algorithms (Hanlon and Anderson, 2009, "Real-Time Gait Event Detection Using Wearable Sensors," Gait Posture, 30(4), pp. 523-527; Maqbool et al., 2017, "A Real-Time Gait Event Detection for Lower Limb Prosthesis Control and Evaluation," IEEE Trans. Neural Syst. Rehabil. Eng.: Publ. IEEE Eng. Med. Biol. Soc., 25(9), pp. 1500-1509). Moreover, the algorithm's self-adaptive nature ensures it can be used in scenarios of varying movement, offering a promising solution for real-time gait phase detection., (Copyright © 2024 by ASME.)

Great toe strength (GTS) weakness is linked to declines in balance and mobility. Accurately assessing GTS, particularly great toe extension strength (GTES), is often neglected in clinical evaluations due to cumbersome and subjective methods. This study aims to characterize the force development curve output from the ToeScale and examine GTES variations with age, sex, BMI, and grip strength (GS) using traditional analyses and machine learning (ML). We conducted a pilot, cross-sectional feasibility study with convenience samples. We assessed GS using a hand-grip dynamometer and GTES using the ToeScale. The data analysis included descriptive statistics, correlations, independent samples t -tests, and accuracy and area under the curve (AUC) scores for three ML models. Thirty-one participants (males: 9; females: 22), 14 young (18-24 years) and 17 older (>65 years) adults, participated in the study. Males had significantly higher peak GTES than females in both age groups. The associations of GTES parameters with BMI and GS varied by age and sex. The ML model accuracies and AUC scores were low-moderate but aligned with traditional analyses. Future studies with larger samples and optimized ML models are needed.

Gravitational forces can induce deviations in body posture from desired configurations in multi-legged arboreal robot locomotion with low leg stiffness, affecting the contact angle between the swing leg's end-effector and the climbing surface during the gait cycle. The relationship between desired and actual foot positions is investigated here in a leg-stiffness-enhanced model under external forces, focusing on the challenge of unreliable end-effector attachment on climbing surfaces in such robots. Inspired by the difference in ceiling attachment postures of dead and living geckos, feedforward compensation of the stance phase legs is the key to solving this problem. A feedforward gravity compensation (FGC) strategy, complemented by leg coordination, is proposed to correct gravity-influenced body posture and improve adhesion stability by reducing body inclination. The efficacy of this strategy is validated using a quadrupedal climbing robot, EF-I, as the experimental platform. Experimental validation on an inverted surface (ceiling walking) highlights the benefits of the FGC strategy, demonstrating its role in enhancing stability and ensuring reliable end-effector attachment without external assistance. In the experiment, robots without FGC only completed 3 out of 10 trials, while robots with FGC achieved a 100% success rate in the same trials. The speed was substantially greater with FGC, achieving 9.2 mm s -1 in the trot gait. This underscores the proposed potential of the FGC strategy in overcoming the challenges associated with inconsistent end-effector attachment in robots with low leg stiffness, thereby facilitating stable locomotion even at an inverted body attitude., (Creative Commons Attribution license.)

This pilot study sought to determine the feasibility of quantifying sensory processing, postural control, motor skill development and participation in daily life in children with idiopathic toe walking (ITW) compared to children without ITW. A nonrandomized, prospective case-control design was employed. Twenty participants were recruited. Computerized weight bearing and postural control data was successfully collected. Differences were found in forefoot/rearfoot weight bearing, balance, sensory-motor abilities and parent reported participation challenges. Sensory processing results were inconclusive. Findings can inform standardized assessment and treatment of ITW.

Background: Physical decline due to aging has been associated with the risk of falls. Minimum toe clearance (MTC) is a gait parameter that might play a role in the mechanism of tripping and falling. However, it is unclear if there are any sex-related effects regarding MTC as people age. The present study investigated if there are sex-related differences in MTC in older active adults., Methods: Twenty-three females and 23 males (F: 65.5 ± 4.8 years; M: 61.9 ± 5.2 years) walked on a treadmill at a preferred walking speed, while kinematic data were obtained at a sampling frequency of 100 Hz and up-sampled to 120 and 240 Hz. MTC was calculated from the kinematics data and evaluated concerning its magnitude (ie, MTC and MTC/leg length), the time between left/right MTC (ie, T-MTC), amount of variability (ie, coefficient of variation [CV] and coefficient of variation modified [CVm]), and temporal structure of variability, that is, the complexity of the time series (ie, MTC α, T-MTC α)., Results: No sex effects were found for MTC/leg length, for the amount of variability (ie, CV and CVm), and for the complexity of the time series (MTC α, T-MTC α). However, females exhibited significantly lower MTC and T-MTC after adjusting for walking speed, mass, and age as covariates., Conclusions: The reduced MTC in females suggests a potential sex-related disparity in the risk of tripping and falling among active older adults., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Predictive neuromuscular simulations are a powerful tool for studying the biomechanics of human walking, and deriving design criteria for technical devices like prostheses or biorobots. Good agreement between simulation and human data is essential for transferability to the real world. The human foot is often modeled with a single rigid element, but knowledge of how the foot model affects gait prediction is limited. Standardized procedures for selecting appropriate foot models are lacking. We performed 2D predictive neuromuscular simulations with six different foot models of increasing complexity to answer two questions: What is the effect of a mobile arch, a toe joint, and the coupling of toe and arch motion through the plantar fascia on gait prediction? and How much of the foot's anatomy do we need to model to predict sagittal plane walking kinematics and kinetics in good agreement with human data? We found that the foot model had a significant impact on ankle kinematics during terminal stance, push-off, and toe and arch kinematics. When focusing only on hip and knee kinematics, rigid foot models are sufficient. We hope our findings will help guide the community in modeling the human foot according to specific research goals and improve neuromuscular simulation accuracy., (© 2024. The Author(s).)

Despite the growing interest, information regarding the psychometric properties of maximal voluntary isometric toe plantarflexion force and rate of force development (RFD) is lacking. Hence, we investigate the test-retest reliability and measurement error of these outcome measurement instruments measured with a custom-built dynamometer. Twenty-six healthy adults participated in a crossed design with four sessions separated by 5-7 days. RFD was quantified using manual onset and calculating the impulse and the slope in the following time windows: 0-50 ms, 0-100 ms, 0-150 ms, 0-200 ms, 0-250 ms. We estimated the systematic bias of the mean, the intraclass correlation coefficient (ICC) and standard error of measurement (SEM) from the agreement and consistency models. The ICC and the SEM agreement for maximal voluntary isometric toe plantarflexion force along the perpendicular axis were respectively 0.87 (95%CI: 0.76, 0.93) and 27 N (22, 32), while along the resultant of the perpendicular and anterior posterior axis they were 0.85 (0.73, 0.92) and 29 N (23, 35). The results of the consistency model were similar as the estimated variance for session was closer to zero. A systematic bias of the mean between session 1 and 3 was found. For the RFD variables, the ICC agreement ranged from 0.35 to 0.65. The measurement process was found to be reliable to assess maximal voluntary isometric toe plantarflexion force but not RFD. However, a familiarization session is mandatory and these results need to be confirmed in less coordinated (e.g. aging population) individuals., Competing Interests: Declaration of Competing Interest none., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: It has recently been recommended that Rate of Force Development (RFD) be evaluated in addition to maximal muscle strength. There are no studies on RFD of toe pressure strength, and its importance in older adults and the extent to which it is associated with aging needs to be clarified. This study purpose was to examine the association between the RFD of toe pressure strength and timed up and go test (TUG) in an age-specific study., Methods: This study is a cross-sectional study. Participants in the study included 159 younger adults (26.3 ± 13.1 years, 52% male) and 88 older adults (75.0 ± 6.2 years, 26% male). The RFD of toe pressure strength was determined from the force-time curve obtained during the toe pressure strength assessment, and the ability to exert maximum muscle force in the shortest possible time was assessed. Regression analysis was performed for each group to test the association between RFD of toe pressure strength and TUG by age., Results: Younger adults showed no association between TUG and RFD of toe pressure strength, and significant association between TUG and RFD of toe pressure strength was found only in the older adults (standard regression coefficient =  - 0.19, p = 0.048)., Conclusion: This study showed a significant association between TUG and RFD of toe pressure strength in older adults. These findings show that RFD is one of the functions that should be assessed, particularly in older adults. Furthermore, it was suggested that approaching RFD could improve gait, standing, and sitting movements., (© 2024. The Author(s), under exclusive licence to European Geriatric Medicine Society.)

Background: The vertical toe position at minimum toe clearance (MTC) in the swing phase is critical for walking safety. Consequently, the joints involved should be strictly controlled and coordinated to stabilize the foot at MTC. The uncontrolled manifold (UCM) hypothesis framework has been used to determine the existence of synergies that stabilize relevant performance variables during walking. However, no study investigated the presence of a multi-joint synergy stabilizing the foot position at MTC and the effects of age and walking speed on this synergy., Research Questions: Is there a multi-joint synergy stabilizing MTC during treadmill walking? Does it depend on the persons' age and walking speed?, Methods: Kinematic data from 23 young and 15 older adults were analyzed using the UCM approach. The participants walked on a treadmill at three speeds: slow, self-selected, and fast. The sagittal and frontal joint angles from the swing and stance legs and pelvis obliquity were used as motor elements and the vertical toe position at MTC was the performance variable. The variances in the joint space that affected (V ORT , 'bad' variance) and did not affect (V UCM , 'good' variance) the toe position at MTC and the synergy index (ΔV) were computed., Results: The ΔV>0 was revealed for all subjects. Walking speed did not affect ΔV in older adults, whereas ΔV reduced with speed in young adults. ΔV was higher for older than for young adults at self-selected and fast speeds, owing to a lower V ORT in the older group., Significance: The vertical toe position at MTC was stabilized by a strong multi-joint synergy. In older adults, this synergy was stronger, as they were better at limiting V ORT than young adults. Reduced V ORT in older adults could be caused by more constrained walking, which may be associated with anxiety due to walking on a treadmill., Competing Interests: Declaration of Competing Interest The authors of the manuscript declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The human toe, characterized by its rigid-flexible structure comprising hard bones and flexible joints, facilitates adaptive and stable movement across varied terrains. In this paper, we utilized a motion capture system to study the adaptive adjustments of toe joints when encountering obstacles. Inspired by the mechanics of toe joints, we proposed a novel design method for a rigid-flexible coupled wheel. The wheel comprises multiple elements: a rigid skeleton, supporting toes, connecting shafts, torsion springs, soft tendons, and damping pads. The torsion springs connect the rigid frame to the supporting toes, enabling them to adapt to uneven terrains and pipes with different diameters. The design was validated through kinematic and dynamic modeling, rigid-flexible coupled dynamics simulation, and stress analysis. Different stiffness coefficients of torsion springs were compared for optimal wheel design. Then, the wheel was applied to a sewer robot, and its performance was evaluated and compared with a pneumatic rubber tire in various experiments, including movement on flat surfaces, overcoming small obstacles, adaptability tests in different terrains, and active driving force tests in dry and wet pipelines. The results prove that the designed wheel showed better stability and anti-slip properties than conventional tires, making it suitable for diverse applications such as pipeline robots, desert vehicles, and lunar rovers., (© 2024 IOP Publishing Ltd.)

Background: This study aimed to investigate whether lower limb joints mutually compensate for each other, resulting in motor synergy that suppresses toe vertical position fluctuation, and whether walking speeds affect lower limb synergy., Methods: Seventeen male university students walked at slow (0.85 ± 0.04 m/s), medium (1.43 ± 0.05 m/s) and fast (1.99 ± 0.06 m/s) speeds on a 15-m walkway while lower limb kinematic data were collected. Uncontrolled manifold analysis was used to quantify the strength of synergy. Two-way (speed × phase) repeated-measures analysis of variance was used to analyze all dependent variables., Results: A significant speed-by-phase interaction was observed in the synergy index (SI) (P  < .001). At slow walking speeds, subjects had greater SI during mid-swing (P  < .001), while at fast walking speeds, they had greater SI during early-swing (P  < .001). During the entire swing phase, fast walking exhibited lower SI values than medium (P  = .005) and slow walking (P  = .027)., Conclusion: Kinematic synergy plays a crucial role in controlling toe vertical position during the swing phase, and fast walking exhibits less synergy than medium and slow walking. These findings contribute to a better understanding of the role of kinematic synergy in gait stability and have implications for the development of interventions aimed at improving gait stability and reducing the risk of falls., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

This study investigates the relationship between ankle and toe strength and functional stability in young adults, with a sample comprising sixteen females and fourteen males. The research employed force platform data to determine the center of foot pressure (COP) and calculated the forward functional stability index (FFSI) through foot anthropometric measurements. Strength measurements of toe and ankle muscles, during maximal isometric flexion and extension, were conducted using force transducers. Notable positive correlations were found between toe flexor strength and FFSI (left flexor: r = 0.4, right flexor: r = 0.38, p < 0.05), not influenced by foot anthropometry. Contrarily, no significant correlation was observed between ankle muscle strength and FFSI, despite a positive correlation with the COP range. The moderate correlation coefficients suggest that while toe flexor strength is a contributing factor to functional stability, it does not solely determine functional stability. These findings highlight the critical role of muscle strength in maintaining functional stability, particularly during forward movements and emphasize the utility of FFSI alongside traditional COP measures in balance assessment. It is recommended to employ a multifaceted approach is required in balance training programs., (© 2024. The Author(s).)

Introduction: Dancing en pointe requires ballet dancers to stand on the tips of their toes while wearing a structured pointe shoe. Understanding the effect of pointe shoes on ballet dancers' biomechanics, function, symptoms and skin health is essential to guide shoe development and ultimately improve dancer performance. Therefore, the purpose of this scoping review was to map the evidence and identify knowledge gaps related to the effect of wearing pointe shoes on professional and recreational ballet dancers. Method: A scoping review was conducted by searching 6 electronic databases and the International Association for Dance Medicine and Science Bibliography. Results: Thirty-five studies were grouped into 5 categories: pointe shoe factors (eg, toe box and shank, pointe shoe status; 9 studies), shoe types (eg, flat shoes vs demi pointe vs pointe; 10 studies), ballet movements (11 studies), symptoms (5 studies), and intrinsic dancer factors (eg, foot type/toe length; 7 studies). Studies were published between 1979 and 2023, with 72% (n = 23) published between 2006 and 2020. Most (86%) of the studies were cross-sectional. Most studies explored biomechanical outcomes and the most common data collection device was force plates (19 studies). Overall, there was an insufficient volume of evidence for specific research aims. Significant gaps in knowledge exist regarding functional and performance-based outcomes, injury outcomes including exploration of factors such as shoe age/usage, and pointe shoe treatment factors. Conclusions: Currently the field of research suffers from threats to ecological validity, with many study methods not reflecting ballet-specific demands or environments. The impact of pointe shoes on ballet dancers is a developing research area, and this scoping review can help guide future research decisions. Studies need to target the knowledge gaps and employ rigorous ecologically valid study designs and ensure that findings inform shoe design and dancer education to minimize injury and maximize comfort and performance., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Most cases of toe walking in children are idiopathic. We used pathology-specific neuromusculoskeletal predictive simulations to identify potential underlying neural and muscular mechanisms contributing to idiopathic toe walking., Methods: A musculotendon contracture was added to the ankle plantarflexors of a generic musculoskeletal model to represent a pathology-specific contracture model, matching the reduced ankle dorsiflexion range-of-motion in a cohort of children with idiopathic toe walking. This model was employed in a forward dynamic simulation controlled by reflexes and supraspinal drive, governed by a multi-objective cost function to predict gait patterns with the contracture model. We validated the predicted gait using experimental gait data from children with idiopathic toe walking with ankle contracture, by calculating the root mean square errors averaged over all biomechanical variables., Findings: A predictive simulation with the pathology-specific model with contracture approached experimental ITW data (root mean square error = 1.37SD). Gastrocnemius activation was doubled from typical gait simulations, but lacked a peak in early stance as present in electromyography. This synthesised idiopathic toe walking was more costly for all cost function criteria than typical gait simulation. Also, it employed a different neural control strategy, with increased length- and velocity-based reflex gains to the plantarflexors in early stance and swing than typical gait simulations., Interpretation: The simulations provide insights into how a musculotendon contracture combined with altered neural control could contribute to idiopathic toe walking. Insights into these neuromuscular mechanisms could guide future computational and experimental studies to gain improved insight into the cause of idiopathic toe walking., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: The intrinsic foot muscles play an important role in medial longitudinal arch support, as well as several extrinsic foot muscles. While various strength training methods specific to intrinsic foot muscles have been conducted, these exercises are associated with certain concerns regarding their effectiveness and difficulty. We developed a new exercise for the intrinsic muscles (MTP flexion exercise)., Objective: The aim was to compare the shear modulus of the toe flexors as the muscle contraction activity during MTP flexion and short-foot exercises using ultrasound shear wave elastography., Methods: Eleven healthy participants were included in this study. The shear modulus of the toe flexor muscles was measured during MTP flexion and short-foot exercises using ultrasound shear wave elastography. The muscle shear modulus was statistically compared between the resting phase, and during the two exercises., Results: The shear modulus during MTP flexion exercise was significantly greater than in the resting phase in the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, quadratus plantae, and flexor digitorum longus. The flexor digitorum longus showed greater shear modulus during MTP flexion exercise than during short-foot exercise., Conclusion: MTP flexion exercise showed equivalent or greater contraction activity in certain intrinsic and extrinsic foot muscles when compared with short-foot exercise. This exercise is considered one of the training options for strengthening the intrinsic muscles of the foot.

Background: Toe function is characterised by the strength and dexterity of toe motion. However, previous studies have mostly focused on the importance of toe strength., Objective: This study aimed to investigate the relationships between flexion strength and dexterity of the toes and physical performance., Methods: Twenty healthy participants were included in this study. The flexion force of each toe was measured using a digital force gauge, and the toe dexterity was evaluated using the marble pick-up and rock-paper-scissors tests. These parameters were statistically analysed in relation to physical performance, including repeated side step and balance ability, which was evaluated using centre of pressure (COP) data during single-leg standing, tiptoe standing, and single-leg drop-jumping., Results: A significant correlation was found between the first toe flexion force and the total trajectory length of the COP during one-leg standing and between the time required for marble pick-up and the rock-paper-scissors score and the COP during single-leg drop-jumping., Conclusion: The results underscore the importance of flexion strength and dexterity of the toes in human physical performance and the necessity for the evaluation and improvement of both functions.

Idiopathic toe-walking (ITW) refers to persistent walking without heel contact for unknown reasons. An underexplored area is the relationship of sensory processing to ITW. This study presents methods to assess sensory differences in individuals with ITW and summarizes results from a pilot testing of the measures. This pilot study included nine children and one young adult with ITW. Ten age-matched controls were recruited to provide a comparison group when norms were not available in the literature. The measures included in this study were as follows: sensory questionnaires; electrodermal activity response to sensory stimuli; monofilaments; biothesiometer; gait on different surfaces; NeuroCom® SMART Balance Master® Sensory Organization Test and Adaptation Test; and ankle position matching. All study procedures were completed in about 3 hours. Children as young as 4 years were able to complete the measures. We observed overall differences in sensory processing, specifically, higher Sensory Processing Measure scores (p = .011), higher resting electrodermal activity (p = .012), increases in heel-toe walking on novel surfaces (p = .034), and more falls with balance perturbation (p = .007) in individuals with ITW. A subset of individuals also showed tactile hyposensitivity (5 out of 10 in the ITW group) and poor equilibrium scores in the Sensory Organization Test (4 out of 9 in the ITW group, 1 unable to complete the test). Our results confirmed the heterogeneity in the etiology of ITW. We propose that further testing in sensory modulation, tactile processing, and vestibular processing is needed to fully explore the impact of sensory processing on children with ITW.

Background: The primary motion of the toes is flexion and extension. The motion results from activity of multiple muscles, and toe disorders may result from muscle dysfunction. The relationships of specific muscles related to toe function is underreported. The purpose of this study was to quantitatively evaluate three-dimensional toe motion resulting from specific muscle contraction using cadavers., Methods: Three-dimensional joint movements of the 1st, 2nd, and 5th toe were produced by applying traction of individual muscles using six Thiel-embalmed cadaver legs. The traction increments were 3 mm, 6 mm, and 9 mm, during which the angle of the distal bone with respect to the proximal bone of each toe joint was measured using a magnetic tracking system., Results: As tendon traction distance increased, the angular measure of the distal bone with respect to the proximal bone at each toe joint increased linearly and three-dimensionally. The flexor hallucis brevis significantly pronated and abducted the 1st toe compared to the extensor hallucis longus and brevis. The flexor digitorum brevis significantly supinated and adducted the 2nd toe compared to the flexor digitorum longus and quadratus plantae, while the extensor digitorum brevis demonstrated significant pronation and abduction compared to the extensor digitorum longus., Conclusions: Three intrinsic muscles produced significant toe motion in frontal and horizontal planes. Our results revealed that there was a proportional relationship between tendon excursion and joint angle, and an antagonistic relationship of muscles acting on the toes. These results can be considered regarding pathogenesis of toe disorders or deformity and regarding treatment such as exercise therapy or tendon transfer., Level of Evidence: V, cadaveric study., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Kota Watanabe reports financial support was provided by a Grant-in-Aid for Scientific Research. Kota Watanabe reports a relationship with a Grant-in-Aid for Scientific Research that includes: funding grants., (Copyright © 2023. Published by Elsevier Ltd.)

Purpose: This study examined physiological and perceptual parameters related to cold-induced vasodilation (CIVD) in the fingers and toes of people with paraplegia and compared them with responses observed in able-bodied individuals., Methods: Seven participants with paraplegia and seven able-bodied individuals participated in a randomized matched-controlled study involving left-hand and -foot immersion in cold water (8 ± 1 °C) for 40 min during exposure to cool (16 ± 1 °C), thermoneutral (23 ± 1 °C), and hot (34 ± 1 °C) ambient conditions., Results: Similar CIVD occurrence was observed in the fingers in the two groups. In toes, three of the seven participants with paraplegia revealed CIVDs: one in cool, two in thermoneutral, and three in hot conditions. No able-bodied participants revealed CIVDs in cool and thermoneutral conditions, while four revealed CIVDs in hot conditions. The toe CIVDs of paraplegic participants were counterintuitive in several respects: they were more frequent in cool and thermoneutral conditions (compared to the able-bodied participants), emerged in these conditions despite lower core and skin temperatures of these participants, and were evident only in cases of thoracic level lesions (instead of lesions at lower spinal levels)., Conclusion: Our findings demonstrated considerable inter-individual variability in CIVD responses in both the paraplegic and able-bodied groups. While we observed vasodilatory responses in the toes of participants with paraplegia that technically fulfilled the criteria for CIVD, it is unlikely that they reflect the CIVD phenomenon observed in able-bodied individuals. Taken together, our findings favor the contribution of central over peripheral factors in relation to the origin and/or control of CIVD., (© 2023. The Author(s).)

Purpose: Humans are amongst few animals that step first on the heel, and then roll on the ball of the foot and toes. While this heel-to-toe rolling pattern has been shown to render an energetic advantage during walking, the effect of different foot contact strategies, on the neuromuscular control of adult walking gaits has received less attention. We hypothesised that deviating from heel-to-toe rolling pattern affects the energy transduction and weight acceptance and re-propulsive phases in gait along with the modification of spinal motor activity., Methods: Ten subjects walked on a treadmill normally, then placed their feet flat on the ground at each step and finally walked on the balls of the feet., Results: Our results show that when participants deviate from heel-to-toe rolling pattern strategy, the mechanical work increases on average 85% higher (F = 15.5; p < 0.001), mainly linked to a lack of propulsion at late stance. This modification of the mechanical power is related to a differential involvement of lumbar and sacral segment activation. Particularly, the delay between the major bursts of activation is on average 65% smaller, as compared to normal walking (F = 43.2; p < 0.001)., Conclusion: Similar results are observable in walking plantigrade animals, but also at the onset of independent stepping in toddlers, where the heel-to-toe rolling pattern is not yet established. These indications seem to bring arguments to the fact that the rolling of the foot during human locomotion has evolved to optimise gait, following selective pressures from the evolution of bipedal posture., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: A method has been developed to assess toe pressure strength in the standing position, taking into account concerns about toe grip strength., Research Question: Which is more associated to postural control capability, the conventional toe grip strength or the newly devised toe pressure strength in the standing position, which is close to the actual movement?, Methods: This study is a cross-sectional study. This study included 67 healthy adults (mean age, 19 ± 1 years; 64% male). The postural control capability was measured using the center-of-pressure shift distance in the anterior-posterior axis. Toe pressure strength in the standing position was assessed using a toe pressure measuring device to evaluate the force of pressure on the floor surface by all toes. During measurement, care is taken to ensure that the toes do not flex. However, toe grip strength in the sitting position was measured using muscle strength for toe flexion in a conventional manner. Statistical analysis was conducted by performing a correlation analysis between each of the measured items. Additionally, multiple regression analysis was used to examine the functions associated with postural control capability., Result: Pearson's correlation analysis revealed that the postural control capability was correlated with toe pressure strength in the standing position (r = 0.36, p = 0.003). Multiple regression analysis demonstrated that only toe pressure strength in the standing position was significantly associated with the postural control capability, even after adjusting for covariates (standard regression coefficient: 0.42, p = 0.005)., Significance: The results of this study indicated that toe pressure strength in the standing position was more strongly associated with the postural control capability in healthy adults than toe grip strength in the sitting position. It has been suggested that a rehabilitation program for toe pressure strength in the standing position would help improve postural control capability., Competing Interests: Declaration of Competing Interest No conflicts of interest to disclose for this study., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Adaptive gait involves the ability to adjust the leading foot in response to the requirement of dynamic environments during walking. Accurate adjustments of the minimum toe clearance (MTC) height and step length can prevent older people from falling when walking and responding to hazards. Although older people with diabetes fall more frequently than healthy older adults, no previous studies have quantified their adaptive gait abilities. This study aimed to investigate the effects of diabetes mellitus on step length and MTC height adjustments using a non-immersive virtual-reality system., Methods: Sixteen young adults (26 ± 5 years, 7 females), 16 healthy older adults (68 ± 5 years, 6 females), and 16 older adults with diabetes (70 ± 5 years, 6 females) completed adaptability tests while walking on a treadmill. A computer system visualised a continuous real-time signal of absolute step length and MTC on a monitor. Each person responded to four discrete participant-specific step length and MTC visual targets that were presented on the same signal. Tasks were to match the peaks of interest on each signal to presented targets. Targets were 10% longer or shorter than the mean baseline step length, and 2.5 cm, and 3.5 cm higher than the mean baseline MTC. When a target was displayed, it remained unchanged for 10 consecutive foot displacement adaptation attempts. Then, the target was removed and a new target or the same target was present after 10 consecutive steps and remained for 10 steps. Each target was randomly presented three times (3 × 10). Step length and MTC height adjustments in response to targets were measured and compared among groups., Results: Mean preferred walking speeds were not different among groups significantly when no targets were presented on the monitor in baseline walking. However, when participants walked on a treadmill while attempting to match step lengths or MTC heights to displayed targets on the monitor, the group with diabetes had reduced step length and MTC adjustments compared with other groups significantly. They showed greater errors (differences between their step lengths/MTC heights and presented targets) on the monitor., Conclusions: This study quantified reduced abilities for older individuals with diabetes to adjust both step length and MTC in response to stimuli compared to healthy older counterparts. Reduced step length and MTC height adjustments can increase falls in at risk populations. The presented virtual-reality system has merits for assessing and training step and MTC adaptation., (© 2023. Crown.)

Background: Idiopathic toe-walking (ITW) is a persistent gait pattern with no known etiology characterized as premature heel rise or no heel contact. We investigated the effects of functional bandaging in children with ITW on heel contact during stance phase and on gait quality., Methods: Nineteen children aged 4 to 16 years with ITW and ten age-matched healthy children were included in the study. Elastic adhesive bandages were applied to children with ITW to assist with dorsiflexion. Before bandaging (T0) and immediately (T1) and 1 week (T2) after initial bandaging, the initial contact, loading response, and midstance subphases of gait were analyzed using light pressure sensors and the Edinburgh Visual Gait Score (EVGS). Ten age-matched children with typical gait participated for comparison in T0. The data were analyzed with Friedman and Wilcoxon signed rank tests for within-group comparisons and Mann-Whitney U tests for between-group comparisons., Results: In T0, for the ITW group, no heel contact was observed during stance. In T1, all of the participants achieved heel contact at initial contact and loading response and 56.8% at midstance. In T2, all of the heels continued contact at initial contact and loading response and 54.3% at midstance. The EVGS significantly improved. The Friedman test showed that there were noteworthy improvements between T0-T1 and T0-T2 in video-based observational gait analysis and EVGSs (P < .001), although no difference was found between T1-T2 in video-based observational gait analysis (P = .913) and EVGSs (P = .450)., Conclusions: In children with ITW, dorsiflexion assistive functional bandaging was an effective tool to help achieve heel contact on the ground and improve walking quality for a short period after application. Further studies with longer follow-up and larger sample sizes are required to confirm the long-term therapeutic effects of this promising functional bandaging.

Background: Intrinsic foot muscle exercises are used in clinical and sports practice to improve performance. Force generation during toe flexion is greater in the standing posture than in the sitting posture; nonetheless, the mechanism underlying the activation of intrinsic foot muscles during force generation and whether there exists a difference between these two postures still remain unclear., Research Question: Are the activities of intrinsic foot muscles affected by standing and sitting postures during gradual force generation?, Methods: Seventeen men participated in the laboratory based cross-sectional study. Each participant performed a force ramp-up toe flexion task from 0% to 80% of the maximal toe flexor strength (MTFS) in sitting and standing postures. High-density surface electromyography signals obtained during the task were determined by calculating the root mean square (RMS). Additionally, modified entropy and coefficient of variation (CoV) were calculated at 20-80 % MTFS for each 10 % MTFS., Results: The RMS between the two postures indicated an interaction effect (p < 0.01). Post-hoc analyses revealed that intrinsic foot muscle activity during the ramp-up task was significantly higher in the standing posture than in the sitting posture at 60 % MTFS (67.53 ± 15.91 vs 54.64 ± 19.28 % maximal voluntary contraction [MVC], p = 0.03), 70 % MTFS (78.11 ± 12.93 vs 63.28 ± 18.65 % MVC, p = 0.01), and 80 % MTFS (81.78 ± 14.07 vs 66.90 ± 20.32 % MVC, p = 0.02). In the standing posture, the modified entropy at 80 % MTFS was lower than that at 20 % MTFS (p = 0.03), and the CoV at 80 % MTFS was higher than that at 20 % MTFS (p = 0.03)., Significance: These results indicated that posture selection is important for high-intensity exercises of the intrinsic foot muscles, such as resistance training. Thus, improving performance related to toe flexor strength might be more effective when conducted under adequate weight-bearing situations, such as in the standing posture., Competing Interests: Declaration of interest The authors declare no conflicts of interest related to this work., (Copyright © 2023 Elsevier B.V. All rights reserved.)

This study investigated whether an increase in toe flexor strength influenced postural control during static upright standing after 12 weeks of multicomponent exercise training in healthy young men. Twelve men (18-23 yrs) performed multicomponent exercise 3 days per week for 12 weeks. Twelve additional age-matched men were recruited for the untrained control group. The multicomponent exercise training consisted of strengthening and balance exercises for the foot and leg muscles. Toe flexor strength, foot arch height and postural control were assessed before, during, and after exercise training. Postural control was evaluated using the path of the centre of pressure, which was obtained with a force plate under three standing conditions: double-leg standing with eyes open, double-leg standing with eyes closed, and single-leg standing with eyes open. The dominant leg was used for single-leg standing. After exercise training, toe flexor strength increased by approximately 32% ( p  < 0.01), whereas the foot arch height did not change. The centre of pressure variables during double-leg standing did not change after exercise training; however, these variables decreased during single-leg standing. None of the variables in the control group changed after exercise training. The relative increase in toe flexor strength was not correlated with the relative improvement in the centre of pressure variables during single-leg standing after 12 weeks of exercise training (total length, r = 0.1734; mean velocity, r = 0.1734; sway area, r = -0.1372). These findings suggest that increased toe flexor strength has no significant effect on static postural control ability after exercise training in young men. Highlights Twelve weeks of multicomponent exercise training aimed at strengthening foot and leg muscles increased toe flexor strength.Multicomponent exercise training did not alter postural stability during double-leg standing, but improved postural stability during single-leg standing.Increased toe flexor strength did not relate to altered postural stability during static upright standings after 12 weeks of exercise training.

Background: Idiopathic toe walking (ITW) is an exclusionary diagnosis given when children toe walk without a medical reason. Treatment effectiveness studies rarely collect data other than ankle range of motion or presence of toe walking., Research Question: To develop a set of outcome measures identified by health professionals for use when providing treatment with children who have ITW, to understand if parents agreed with this set, and if parents believed they could perform these measures in clinician absence., Methods: Study 1 developed consensus and agreement on outcome measures for children receiving treatment for ITW through the modified Delphi technique with 10 expert health professionals. Parents of children who toe walked were invited to participate in an online survey for the second study, in which they were asked to rate the importance of these measures and if they believed they may be able to collect the data about their child without the health professional being present., Results: Ten health professionals developed nine questions and assessments through consensus and agreement over the three rounds. There were 34 parents providing information about satisfaction with toe walking assessments and treatments. Of these, 27 provide detailed responses about the outcome questions and assessments. The majority (91 % of 24 parents) in support of the outcome measures identified by experts. Parents expressed a willingness to self-complete questions or be taught assessments to monitor their child's progress., Significance: Use of these clinically based measures may enable consistent data collection regardless of the setting and provide the foundation for large data pooling in future treatment research., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Introduction: This study investigated how toe flexor muscles are related to postural stability in 11 ballet dancers and 12 non-dancers.
Methods: Toe flexor strength (TFS), cross-sectional areas (CSA) of the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, flexor hallucis longus (FHL), and flexor digitorum longus, and center of pressure (COP) displacement during single-leg demi-pointe were measured. Correlations between toe flexor strength and COP displacement and between CSA and COP displacement within each group were calculated using Pearson's correlation coefficient or Spearman's correlation coefficient.
Results: The dancers showed smaller COP displacement than the non-dancers (p < 0.05). Toe flexor strength in dancers was moderately negatively correlated with COP displacement in the anterior-pos- terior direction (r = -0.54, p < 0.01) and total COP displacement (r = -0.57, p < 0.01). Only the CSA of the FHL in dancers exhibited a significant negative correlation with COP displacement in the anterior-posterior direction (r = -0.42, p < 0.05) and total COP displacement (r = -0.52, p < 0.01).
Conclusion: The present study found a relationship between the toe flexor strength and COP displacement and CSA of toe flexor muscles and COP displacement during one-legged demi-pointe standing. These results suggest that the development of the toe flexor muscles may be involved in the balance control of dancers.

Background: The aim of this study is to examine the age-related changes in the toe grip strength and its differences from hand grip strength and knee extension strength using cross-sectional data., Methods: Of participants aged 65 years over who underwent health checkups for lifestyle-related diseases in 2018, 307 men and women met the criteria. Toe grip strength, hand grip strength, and knee extension strength were also measured as optional tests. The participants were divided into five groups categorized by every 5 years of age (Group 65-85). The data were analyzed with multiple comparisons using the linear mixed multilevel model to examine the following categories: association between age and muscle strength, differences in the pattern of change, and gender, using the 65-69 years group as a reference., Results: In men, there were interaction effects between the factors of age and muscle, but in women there were not. Toe grip strength was significantly lower in Group 70, 75, 80, and 85 in men, lower in Group 85 than in 65 in women. Hand grip strength was significantly lower in Group 85 than in 65 in both men and women. There was no significant difference in knee extension strength among the age groups for both men and women., Conclusions: The decline in toe grip strength may occur earlier and in a different pattern from hand grip strength and knee extension strength in men., (© 2022. The Author(s).)

The mechanical output at the ankle provides key contribution to everyday activities, particularly step/stair ascent and descent. Age-related decline in ankle functioning can lead to an increased risk of falls on steps and stairs. The rising up-on-the-toes (UTT) 30-second test (UTT-30) is used in the clinical assessment of ankle muscle strength/function and endurance; the main outcome being how many repetitive UTT movements are completed. This preliminary study describes how inertial measurement units (IMUs) can be used to assess the UTT-30. Twenty adults (26.2 ± 7.7 years) performed a UTT-30 at a comfortable speed, with IMUs attached to the dorsal aspect of each foot. Use of IMUs' angular velocity signal to detect the peak plantarflexion angular velocity (p-fAngVel peak ) associated with each repeated UTT movement indicated the number of UTT movements attempted by each participant. Any UTT movements that were performed with a p-fAngVel peak 2SD below the mean were deemed to have not been completed over a sufficiently 'full' range. Findings highlight that use of IMUs can provide valid assessment of the UTT 30-second test. Their use detected the same number of attempted UTT movements as that observed by a researcher (average difference, -0.1 CI, -0.2 - 0.1), and on average 97.6 ± 3.1% of these movements were deemed to have been completed 'fully'. We discuss the limitations of our approach for identifying the movements not completed fully, and how assessing the consistency in the magnitude of the repeated p-fAngVel peak could be undertaken and what this would indicate about UTT-30 performance., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Idiopathic toe walking (ITW) is a diagnosis given to children who walk with an absence or limitation of heel strike in the contact phase of the gait cycle, that are otherwise typically developing. There is emerging evidence that this gait pattern may occur in children who experience tactile sensory processing challenges. This feasibility study aimed to determine if children were able to respond to a sensory stimulus during a fMRI. Children aged between 8-16 years of age, with and without idiopathic toe walking were recruited from general public advertising. Participants were required to perform a two-point discrimination test (task block) and press a button without being tested (control block) during an fMRI using a standard block design. Activation differences were examined in the left frontal pole, left supramarginal gyrus, left parahippocampal gyrus, left paracingulate gyrus and the right superior temporal. Five children were in the typically developing (TD) group and three were in the ITW group. There were between-group activation differences in the decision-making block compared to the control block in the left frontal lobe, parahippocampal gyrus and the right superior temporal gyrus. There was greater variation in activation in the left supramarginal gyrus and the left paracingulate gyrus in the ITW group compared to the typically developing group. Based on this study a future sample size of 15 children per group will be required to detect an adequate effect across chosen regions of interest Conducting fMRI using two-point discrimination testing on this population is feasible. Further research is required with larger population sizes to determine if brain activation patterns during the sensory input decision-making process are different in this population.

Background: Floating toe (FT): inadequately in contact with the ground and flexible flat foot (FFF) are frequently seen in children. According to some reports, inadequate foot muscle strength may cause FT or FFF.Therefore, a relationship may exist between arch formation, FT, and pedal muscle strength. This study aimed to evaluate the correlation of FT with plantar arch posture and body composition, including overall muscle mass., Methods: We conducted our own cohort study in addition to the Japan Environment and Children's Study conducted by the Ministry of the Environment, Japan. Out of 705 eight-year-old children participating in this adjunct study, 578 with recorded footprints were included. Body composition (body weight, body fat percentage, and predicted muscle mass) was assessed using body composition analyzer. Presence of FT or FFF was evaluated using foot pressure plate. We calculated the FT score (small FT score indicates insufficient ground contact of the toes) and the Chippaux-Smirak Index (CSI) using images of the plantar footprint., Results: The FT score (an indicator of FT) showed no significant correlation with CSI (an indicator of plantar arch posture). Moreover, no significant correlations between the predicted muscle mass, FT score, and CSI were observed., Conclusions: This is the first report that assessed the relationship of FT with plantar arch posture and body composition in children. This study indicated that muscle strength might not be a major factor for FT and FFF development in children., Competing Interests: Declaration of interest none., (Copyright © 2022 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Background: Idiopathic toe walking (ITW) is an exclusionary diagnosis. There has been limited exploration of lower limb active range of motion and strength measures in children with ITW. This researched aimed to determine any differences in lower limb muscle active range of motion and strength in children who have ITW, compared to normative data collected from children who displayed typical gait., Methods: Children were recruited with had a diagnosis of ITW, aged between 4 and 10 years, and no recent treatment. Data collected included parent reported data such as time spent toe walking, percentage of time spent toe walking, and clinician collected data such as age, height and weight. Joint ranges of motion and strength measures were collected by an experience clinician. Active and weight bearing joint ranges of motion were evaluated with a goniometer or digital inclinometer. Lower limb muscle strength measures were evaluated with a hand-held dynamometer. Published normative data sets were used for comparison. Measures were analysed with regression analyses to determine differences between groups in different measures, considering measures known to impact range and strength. Odds ratios (OR), 95% confidence intervals (CI) and p values were reported., Results: Twenty-six children with ITW participated. Reduced weight bearing ankle range of motion, when measured with the knee bent, was associated with being in the ITW group (p = 0.009), being older (p < 0.001) and weighing less (p < 0.001). Reduced ankle plantar flexion range was only associated with being in the ITW group (p = 0.015). For all lower limb strength measures, excluding hip external rotation, children who displayed greater strength, did not toe walk (p < 0.002), were older (p < 0.001) and weighed more (p < 0.014). with ITW., Conclusion: Children with ITW displayed reduced overall plantar and dorsiflexion at the ankle, compared to non-toe walking children. Reduced plantarflexion is children with ITW has not been described before, however reduced dorsiflexion is commonly reported. Children with ITW were weaker in many lower limb measures, even when age and weight were considered. This should lead clinicians and researchers to pay greater attention to lower limb strength measures in this population., (© 2022. The Author(s).)

Purpose: The effective mechanical advantage (EMA) of the plantarflexor muscles is important for gait function and is likely different from typical in equinus gait. However, this has never been quantified for children who idiopathically toe-walk (ITW), despite being routinely altered through clinical intervention., Methods: This study quantified the Achilles tendon and ground reaction force (GRF) moment arms, and the plantarflexor EMA of 5 children who ITW and 14 typically developing (TD) children, whilst walking on an instrumented treadmill., Results: There was no difference in the Achilles tendon moment arm length throughout stance between groups (p > 0.05). Children who ITW had a significantly greater GRF moment arm length in early stance (20-24% p = 0.001), but a significantly shorter GRF moment arm length during propulsion (68-74% of stance; p = 0.013) than TD children. Therefore, children who ITW had a greater plantarflexor EMA than TD children when active plantarflexion moments were being generated (60-70% of stance; p = 0.007). Consequently, it was estimated that children who ITW required 30% less plantarflexor muscle force for propulsion., Conclusion: Clinical decision making should fully consider that interventions which aim to restore a typical heel-toe gait pattern risk compromising this advantageous leverage and thus, may increase the strength requirements for gait., (© 2022. The Author(s).)

Geckos show versatility by rapidly maneuvering on diverse complex terrain because they benefit from their distributed, setae-covered toes and thus have the ability to generate reliable and adaptive attachment. Significant attention has been paid to their adhesive microstructures (setae), but the effectiveness of the gecko's adaptive attachment at the level of toes and feet remains unclear. In order to better understand the geckos' attachment, we first focused on the deployment of toes while challenging geckos to locomote on varying inclines. When the slope angle was less than 30°, their feet mainly interacted with the substrate using the bases of the toes and generated anisotropic frictional forces. As the slope angle increased to 90°, the participation of the toe bases was reduced. Instead, the setae contribution increased for the middle three toes of the front feet and for the first three toes of the hind feet. As the incline changed from vertical to inverted, the adhesive contribution of the toes of the front feet became more equal, whereas the effective adhesion contact of the hind feet gradually shifted to the toes oriented rearwards. Second, a mathematical model was established and then suggested the potential advantages of distributed control among the toes to regulate foot force. Finally, a physical foot model containing five compliant, adjustable toes was constructed and validated the discoveries with regard to the animals. Using the gecko toes' control strategies, the artificial foot demonstrated diverse behavior regulating attachment forces. The success of the foot prototype not only tested our understanding of the mechanism of biological attachment, but also provided a demonstration for the design and control of gecko-inspired attachment devices, grippers and other manipulators., (Creative Commons Attribution license.)

Background: It is unclear whether the toe grip force (TGF) of the dominant foot (DF) and the lower limb function asymmetry (LLFA) in older adults are associated with fall risk. Therefore, this study aimed to investigate the effect of lower limb properties (such as TGF, muscle strength, and plantar sensation) on the risk of falls in older adults, while considering the foot dominance and asymmetry of lower limb function., Methods: This study was a cross-sectional study. We determined whether the lower limb function of the DF and non-dominant foot (non-DF) and LLFA had any effect on the fall risk in 54 older adults (mean ± standard deviation: 72.2 ± 6.0, range: 60-87 years). We examined the participants' fall history, Mini-Mental State Examination (MMSE) score, lower limb function, and LLFA. To determine fall risk factors, we performed logistic regression analysis, with presence or absence of falls as the dependent variable., Results: The independent variables were age, sex, MMSE score, two-point discrimination of the heel (non-DF) as plantar sensation index, and the TGF of both feet. Only the TGF of the DF was identified as a risk factor for falls (p < 0.05)., Conclusions: In older adults, clinicians should focus on the TGF of the DF as a risk factor for falls., Trial Registration: This study was retrospectively registered. https://center6.umin.ac.jp/cgi-bin/ctr/ctr&#95;up&#95;rec&#95;f1.cgi ., (© 2022. The Author(s).)

Background: The size of the plantar intrinsic and extrinsic foot muscles has been shown to be associated with toe flexor strength (TFS). Previous studies adopted the size of limited plantar intrinsic foot muscles or a compartment containing several muscles as an independent variable for TFS. Among the plantar intrinsic and extrinsic foot muscles, therefore, it is unclear which muscle(s) primarily contributes to TFS production. The present study aimed to clarify this subject., Methods: In 17 young adult men, a series of anatomical cross-sectional area of individual plantar intrinsic and extrinsic foot muscles was obtained along the foot length and the lower leg length, respectively, using magnetic resonance imaging. Maximal anatomical cross-sectional area (ACSA max ) and muscle volume (MV) for each constituent muscle of the plantar intrinsic foot muscles (flexor hallucis brevis; flexor digitorum brevis, FDB; abductor hallucis; adductor hallucis oblique head, ADDH-OH; adductor hallucis transverse head, ADDH-TH; abductor digiti minimi; quadratus plantae) and extrinsic foot muscles (flexor hallucis longus; flexor digitorum longus) were measured. TFS was measured with a toe grip dynamometry., Results: TFS was significantly associated with the ACSA max for each of the ADDH-OH (r = 0.674, p = 0.003), ADDH-TH (r = 0.523, p = 0.031), and FDB (r = 0.492, p = 0.045), and the MV of the ADDH-OH (r = 0.582, p = 0.014). As for the ADDH-OH, the correlation coefficient with TFS was not statistically different between ACSA max and MV (p = 0.189). Stepwise multiple linear regression analysis indicated that ACSA max and MV of the ADDH-OH alone explained 42 and 29%, respectively, of the variance in TFS., Conclusion: The ADDH-OH is the primary contributor to TFS production among the plantar intrinsic and extrinsic foot muscles as the result of the stepwise multiple linear regression analysis., (© 2022. The Author(s).)

Toe muscular strength plays an important role in enhancing athletic performance because the forefoot is the only part of the body touching the ground. In general, muscular strength increases with age throughout adolescence, and sex-related difference in muscular strength becomes evident during childhood and adolescence. However, toe muscular strength is known to be levelled off after late adolescence in both sexes. For adolescent populations, therefore, the association of toe muscular strength with physical performance might differ with age and/or sex. This study aimed to investigate differences in relationships between toe muscular strength and vertical jump performance across sex and age in adolescent populations. The maximum isometric strength of the toe muscles and vertical jump height (VJ) were assessed in 479 junior high school students (JH) aged 12-14 years (243 boys and 236 girls) and 465 high school students (HS) aged 15-18 years (265 boys and 200 girls). Two types of measurements were performed to evaluate the toe muscular strength: toe gripping strength (TGS) with the metatarsophalangeal joint in the plantar flexed position and toe push strength (TPS) with the metatarsophalangeal joint in the dorsiflexed position. TGS and TPS were normalized to body weight. Two-way ANOVA showed that TGS had significant main effects of sex (boys > girls) and age (HS > JH) while TPS only had a significant main effect of sex (boys > girls). When the effects of sex and age were separately analyzed, VJ was significantly correlated with TGS in JH girls, HS girls, and JH boys (r = 0.253-0.269, p < 0.05), but not in HS boys (r = 0.062, p = 0.3351). These results suggest that toe muscular strength is relatively weakly associated with vertical jump performance in adolescent boys and girls, but the association would not be established in high school boys., Competing Interests: The authors have declared that no competing interests exist.

In mammals, multi-tissue regeneration is largely restricted to the distal portion of the digit tip and involves the formation of a blastema, a transient, proliferating cell mass that reforms the diverse tissues of the digit. Historically little was known about the mammalian blastema but with recent advances in single cell transcriptomic approaches and genetic lineage tracing, a more precise understanding of this critical structure has begun to emerge. In this review we summarise the cellular mechanisms underlying adult mammalian digit tip regeneration. We posit that understanding how some mammals naturally regenerate complex tissues will lead to strategies for enhancing regenerative abilities in humans., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

New Findings: What is the central question of this study? What are the in vivo operating lengths of the gastrocnemius muscle in children who idiopathically toe-walk? What is the main finding and its importance? Children who idiopathically toe-walk operate at more plantarflexed positions but at longer fascicle lengths than typically developing children during gait. However, these ranges utilised during gait correspond to where children who idiopathically toe-walk are optimally strong. This should be considered when prescribing clinical treatments to restore typical gait., Abstract: Children who idiopathically toe-walk (ITW) habitually operate at greater plantarflexion angles than typically developing (TD) children, which might result in shorter, sub-optimal gastrocnemius fascicle lengths. However, currently no experimental evidence exists to substantiate this notion. Five children who ITW and 14 TD children completed a gait analysis, whilst gastrocnemius fascicle behaviour was simultaneously quantified using ultrasound. The moment-angle (hip, knee and ankle) and moment-length (gastrocnemius) relationships were determined from isometric maximum voluntary contractions (MVC) on an isokinetic dynamometer combined with ultrasound. During gait, children who ITW operated at more plantarflexed angles (Δ = 20°; P = 0.013) and longer muscle fascicle lengths (Δ = 12 mm; P = 0.008) than TD children. During MVC, no differences in the peak moment of any joint were found. However, peak plantarflexor moment occurred at significantly more plantarflexed angles (-16 vs. 1°; P = 0.010) and at longer muscle fascicle lengths (44 vs. 37 mm; P = 0.001) in children who ITW than TD children. Observed alterations in the moment-angle and moment-length relationships of children who ITW coincided with the ranges used during gait. Therefore, the gastrocnemius muscle in children who ITW operates close to the peak of the force-length relationship, similarly to TD children. Thus, this study indicates that idiopathic toe-walking is truly an ankle joint pathology, and children who ITW present with substantial alterations in the gastrocnemius muscle functional properties, which appear well adapted to the characteristic demands of equinus gait. These findings should be considered when prescribing clinical treatments to restore typical gait., (© 2021 The Authors. Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Background: This study aimed to investigate the differences in plantar pressure during various athletic activities on natural grass and artificial turf., Methods: Twenty-one athletes were fitted with properly sized soccer shoes and corresponding F-Scan system insoles and performed walking, running, vertical jumping and cutting activities to the right and left sides on both natural and artificial turf., Results: There were no statistically significant differences between natural grass and artificial turf in peak pressure, maximum force and force-time integral during all the athletic activities (P˃0.05). On both turfs, the highest peak pressure and maximum force values occurred during running and cutting to the right, and the highest force-time integral value occurred during cutting to the right. There were no statistically significant differences between the two turfs in peak pressure in the various anatomical regions during any of the athletic activities (P˃0.05). The peak pressure was the highest on the first metatarsal and the hallux during all five activities. A clinically meaningful difference between the surfaces in peak pressure on the second to fifth metatarsals was found during walking, indicating more loading on artificial turf than on natural grass. There was more loading on artificial turf than on natural grass during cutting left and at hallux and third toe on natural grass during cutting right. However, these differences were not statistically significant (P˃0.05)., Conclusions: The results of this study suggest that it is important to limit or prevent athletes from undertaking certain activities that increase the risk of re-injury during rehabilitation.

Controlling minimum toe clearance (MTC) is considered an important factor in preventing tripping. In the current study, we investigated modifications of neuro-muscular control underlying toe clearance during steady locomotion induced by repeated exposure to tripping-like perturbations of the right swing foot. Fourteen healthy young adults (mean age 26.4 ± 3.1 years) participated in the study. The experimental protocol consisted of three identical trials, each involving three phases: steady walking (baseline), perturbation, and steady walking (post-perturbation). During the perturbation, participants experienced 30 tripping-like perturbations at unexpected timing delivered by a custom-made mechatronic perturbation device. The temporal parameters (cadence and stance phase % ), mean, and standard deviation of MTC were computed across approximately 90 strides collected during both baseline and post-perturbation phases, for all trials. The effects of trial (three levels), phase (two levels: baseline and post-perturbation) and foot (two levels: right and left) on the outcome variables were analyzed using a three-way repeated measures analysis of variance. The results revealed that exposure to repeated trip-like perturbations modified MTC toward more precise control and lower toe clearance of the swinging foot, which appeared to reflect both the expectation of potential forthcoming perturbations and a quicker compensatory response in cases of a lack of balance. Moreover, locomotion control enabled subjects to maintain symmetric rhythmic features during post-perturbation steady walking. Finally, the effects of exposure to perturbation quickly disappeared among consecutive trials., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

Floating toe (FT) is a frequently seen condition in which a toe is inadequately in contact with the ground. Although toes play an important role in stabilizing standing posture and walking, many aspects of the effects of FT on the body remain unclear. To our knowledge, there have been no reports about the relationship between FT and postural stability, especially in children. This study aimed to clarify the prevalence of FT and its relationship with static postural stability in children. Of the 400 children aged 8 years who participated in our cohort study, 396, who were examined for static postural stability, were included in this study. Postural stability and FT were assessed using a foot pressure plate. The sway path length of the center of pressure and the area of the ellipse defined as the size of the area marked by the center of pressure, were measured as an evaluation of static postural stability. We calculated the "floating toe score (FT score: small FT score indicates insufficient ground contact of the toes)" using the image of the plantar footprint obtained at the postural stability measurement. The rate of FT was elevated at more than 90%, and the FT score in the eyes-closed condition was significantly higher than that in the eyes-open condition in both sexes. The FT score significantly correlated with the center of pressure path and area. Our results suggest that ground contact of the toes is not directly related to static postural stability in children, but it may function to stabilize the body when the condition becomes unstable, such as when the eyes are closed., Competing Interests: The authors have declared that no competing interests exist.

Background: Stronger toe flexor muscles improve performance outcomes in children, including balance, sprinting, jumping and side stepping. Toe flexor strength (TFS) is recommended as part of the clinical assessment of foot function in children. Fixed dynamometry, rather than handheld, is the gold standard of measurement; however, it can be prohibitively costly. No fixed dynamometer reliability studies on toe flexion have been conducted in children to date., Research Questions: Does the novel fixed hand-held dynamometer (HHD) protocol provide reliable intra-rater and test-retest measurements of toe flexor strength in children aged 10 to 12?, Methods: Two trials were recorded from 14 healthy children (10-12 years), 7-14 days apart by the same rater. A Lafayette HHD (model 01163) measured peak force. The HHD was secured in a mobile custom mould below a step with a strap, which secured the foot of the participant. The receptor pads of the HHD were level with the upper surface of the step, maintaining neutral toe joints at rest. The participant was seated on an adjustable stool to ensure the hip, knee and ankle were each at 90° flexion, with the testing foot flat on the upper surface of the step. The averages of three maximal five second efforts were used for data analysis using a two-way mixed effects model with repeated measures ANOVA (intraclass correlation coefficient ICC 3,3). Standard error of measurement (SEM) was calculated to determine the absolute between trial variability., Results: The novel fixed HHD protocol provided excellent test-retest reliability with small measurement error for hallux (ICC 3,3 = 0.93, 95 % CI 0.78-0.98, SEM = 4.31 N) and lesser toe flexor strength testing (ICC 3,3 = 0.96, 95 % CI 0.87-0.99, SEM = 1.86 N)., Significance: The fixed HHD protocol described in this study has excellent reliability for the test-retest evaluation of children's toe flexor strength., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Mammalian epimorphic regeneration is rare and digit tip regeneration in mice is the best-studied model for a multi-tissue regenerative event that involves blastema formation. Digit tip regeneration parallels human fingertip regeneration, thus understanding the details of this response can provide insight into developing strategies to expand the potential of human regeneration. Following amputation, the digit stump undergoes a strong histolytic response involving osteoclast-mediated bone degradation that is spatially and temporally linked to the expansion of blastema osteoprogenitor cells. Blastemal differentiation occurs via direct intramembranous ossification. Although robust, digit regeneration is imperfect: The amputated cortical bone is replaced with woven bone and there is excessive bone regeneration restricted to the dorsal-ventral axis. Ontogenetic and phylogenetic analysis of digit regeneration in amphibians and mammals raise the possibility that mammalian blastema is a product of convergent evolution and we hypothesize that digit tip regeneration evolved from a nonregenerative precondition. A model is proposed in which the mammalian blastema evolved in part from an adaptation of two bone repair strategies (the bone remodeling cycle and fracture healing) both of which are conserved across tetrapod vertebrates. The view that epimorphic regeneration evolved in mammals from a nonregenerative precondition is supported by recent studies demonstrating that complex regenerative responses can be induced from a number of different nonregenerative amputation wounds by specific modification of the healing response., (© 2020 Wiley Periodicals, Inc.)