Pressure characteristics in painful pes cavus feet resulting from Charcot-Marie-Tooth disease

Charcot–Marie–Tooth (CMT) disease often presents with peripheral muscle imbalance associated with a painful cavus (medial high-arched) foot deformity which becomes increasingly severe and rigid as the disease progresses. The purpose of this study was to investigate the effect of pes cavus on foot pain and dynamic plantar pressure in CMT, and to explore the relationships between plantar pressure and pain. Sixteen participants diagnosed with CMT and painful pes cavus were assessed for foot posture, ankle dorsiflexion range of motion, levels of foot pain, functional impairment, health-related quality of life and plantar pressure distribution while walking. Plantar pressure parameters (mean pressure, peak pressure, pressure–time integral) and contact duration were measured using the Novel Pedar^® in-shoe capacitance transducer system and the foot was divided into rearfoot, midfoot and forefoot regions for analysis. Increasing cavus foot deformity was associated with more widespread foot pain and increased pressure under the forefoot and midfoot regions. In contrast, peak pressure decreased under the rearfoot. Neither relationship was found between foot pain intensity and any of the pressure variables, nor was ankle dorsiflexion range of motion correlated with pain location, intensity or degree of pes cavus. Although pes cavus in CMT is associated with substantial pain and dysfunction, there is no clear link between foot pain and plantar pressure. The more severe the degree of pes cavus, however, the more pressure develops under the lateral margin of the foot; probably as a result of the changed foot–ground contact seen during gait.     

Dynamic plantar pressure patterns in children and adolescents with Charcot-Marie-Tooth disease

BackgroundThe dynamic plantar pressure patterns of children and adolescents with Charcot-Marie-Tooth (CMT) disease and its relationship to musculoskeletal alterations may help to understand the natural history of the disease and improve therapeutic interventions.Research questionThe study compared dynamic plantar pressure patterns in children and adolescents with and without CMT. It also tested the associations between isometric muscle strength (IMS), passive range of motion (ROM), foot posture and dynamic plantar pressure patterns in CMT.MethodsThis cross-sectional study compared children and adolescents (aged 8–18 years) with CMT (n = 40) with a typical group (n = 40). The plantar pressure distribution during gait was recorded, and the contact area (CA), peak pressure (PP), contact time (CT) and pressure-time integral (PTI) in five foot regions (rearfoot, midfoot lateral, midfoot medial, lateral forefoot and medial forefoot) were analysed. The IMS of the dorsiflexors and plantar flexors, passive ROM, and foot posture were also recorded.ResultsPP (medial midfoot and medial forefoot) and PTI (rearfoot, lateral midfoot and medial forefoot) were higher in children with CMT compared with the typical group. The adolescents with CMT presented a less CA (whole foot) and a higher CT (medial midfoot) when compared with typical group. For CMT, in the medial midfoot, plantar flexor IMS associated with PP (β=-11.54, p = 0.01) and PTI (β=-3.38, p = 0.04); supinated foot posture associated with PP (β = 33.89, p = 0.03) and PTI (β = 12.01, p = 0.03).SignificanceChildren with CMT showed clear changes in most of the dynamic plantar pressure variables, while adolescents with CMT showed changes mostly in CA and CT. This information together with the associations established between supinated foot, dorsiflexion ROM and plantar flexions IMS can be useful for guiding rehabilitation professionals in their therapies.     

Effects of backpack carriage on foot-ground relationship in children during upright stance

Although the scientific community widely recognizes that backpack carriage in primary school children represents a critical issue, its consequences in terms of postural alterations and possible onset of musculoskeletal pathologies are still not fully understood. In particular, little information is available on the way load carriage modifies the foot-ground relationship in terms of plantar pressure distribution. This issue is of particular relevance, because the presence of a load alters the physiological weightbearing functions and, when mechanical overloading is repeated in time, it can act as a co-factor in promoting foot discomfort or pain. On the basis of these considerations, this study analyzed plantar pressure maps of 359 children attending primary schools (6-10 years old) under static upright posture conditions, to assess the magnitude and features of effects originated by load carriage on the foot-ground relationship. The collected data showed that backpack introduces significant increases in overall contact area (up to 10%) and in the plantar pressure peaks in midfoot and forefoot regions (20-30%). A significant shift in the average position of the center of pressure towards the forefoot was also observed, as an indicator of the body's attempt to restore the initial balance conditions threatened by the load. These results suggest that heavy loads, in the case of significant exposure times, may increase the risk of foot discomfort and act as a co-factor in the onset of foot structure alterations or pathologies.     

An optimized design of in-shoe heel lifts reduces plantar pressure of healthy males

Conventional heel lift with a flat surface increases the risk of foot problems related to higher plantar pressure and decreased stability. In this study, an optimized design of in-shoe heel lifts developed to maintain the midfoot function was tested to investigate if the plantar pressure distribution was improved. The design was based on three dimensional foot plantar contour which was captured by an Infoot 3D scanning system while the heel was elevated by a heel wedge. To facilitate midfoot function, an arch support was designed to support the lateral longitudinal arch, while allowing functional movement of the medial longitudinal arch. Twenty healthy male subjects were asked to walk along an 8 m walkway while wearing high-cut footwear with and without the optimized heel lift. Peak pressure, contact area and force–time integral were measured using the Pedar insole system. Range and velocity of medial-lateral center of pressure during forefoot contact phase and foot flat phase were collected using a Footscan pressure plate. Compared to the shoe only condition, peak pressure under the rearfoot decreased with the optimized heel lift, while no increase of peak pressure was observed under the forefoot and midfoot regions, indicating improved plantar pressure distribution. The findings of this study suggest that this optimized heel lift has better biomechanical performance than a conventional flat heel lift. Results from this study may have implications for insole and shoe last design, especially for people who need additional heel height without sacrificing midfoot function.     

Foot loading patterns can be changed by deliberately walking with in-toeing or out-toeing gait modifications

The present study shows how foot loading patterns may be deliberately altered by either in-toeing or out-toeing gait during barefoot walking. The results indicate that in-toeing increasingly loads the lateral aspects of the midfoot and forefoot by as much as 61% and 49%, respectively, whereas out-toeing intensifies the load on the medial aspect, i.e. predominantly the medial midfoot and medial forefoot by as much as 72% and 52%. These findings are being discussed with respect to the potential benefits of consciously altering the gait pattern in order to off-load certain plantar regions.     

Gait, balance and plantar pressures in older people with toe deformities

Older people with toe deformities have been identified as having an increased risk of falling. Little is known, however, about the biomechanical changes that might contribute to this increased risk. Therefore, the purpose of this study was to determine whether older people with hallux valgus and lesser toe deformities displayed different gait, balance and plantar pressure characteristics compared to individuals without toe deformities. The presence of hallux valgus and lesser toe deformities were assessed for 312 community-dwelling older men and women. Spatiotemporal gait parameters were measured using the GAITrite^® system, postural sway was assessed on two surfaces using a sway-meter and dynamic plantar pressure distribution was measured using an Emed-AT4 pressure plate. The results indicated that, although there were no effects of toe deformities on spatiotemporal gait characteristics or postural sway, older people with hallux valgus (n = 36) and lesser toe deformities (n = 71) were found to display altered forefoot plantar pressure patterns. These findings suggest that toe deformities alter weight distribution under the foot when walking, but that the relationship between toe deformities and falls may be mediated by factors other than changes in spatiotemporal gait parameters or impaired postural sway.     

Forefoot pathology in relation to plantar pressure distribution in patients with rheumatoid arthritis: A cross-sectional study in the Amsterdam Foot cohort

BackgroundIn patients with rheumatoid arthritis (RA), both high and low forefoot plantar pressures have been reported. Better understanding of pathology in the forefoot associated with altered pressure distribution in patients with RA could help to better formulate and specify goals for treatment with foot orthoses or therapeutic footwear.ObjectivesTo investigate the association of plantar pressure with disease activity and deformity in the forefoot in patients with rheumatoid arthritis and forefoot symptoms.MethodsA cross sectional study, using data of 172 patients with rheumatoid arthritis and forefoot symptoms, was conducted. Peak pressure (PP) and pressure time integral (PTI) in the forefoot were measured with a pressure platform. Forefoot deformity was assessed using the Platto score. Forefoot disease activity was defined as swelling and/or pain assessed by palpation of the metatarsophalangeal joints. The forefoot was divided in a medial, central and lateral region, in which the following conditions could be present: 1) no pathology, 2) disease activity, 3) deformity or 4) disease activity and deformity. A multilevel analysis was performed using condition per forefoot region as independent variable and PP or PTI in the corresponding region as dependent variable.ResultsStatistically significant higher plantar pressures were found in forefoot regions with deformities (RR 1.2, CI 1.1-1.3, P<0.0001), compared to forefoot regions without forefoot pathology. No significant differences in plantar pressures were found when solely forefoot disease activity was present in forefoot regions.SignificanceForefoot deformities are related to higher plantar pressures measured in the corresponding forefoot regions. The absence of an association between local disease activity and plantar pressure might be explained by the low prevalence of metatarsophalangeal joint pain or swelling. Future research with sensitive imaging measures to detect disease activity is recommended to reveal the effect of forefoot disease activity on plantar pressure.     

The mechanics behind the image: foot and ankle pathology associated with gastrocnemius contracture

Contracture of the gastrocnemius musculature is a prevalent finding in the setting of foot and ankle pathology. Tightness of the posterior musculotendinous structures in the leg limits ankle range of motion and affects an equinus posture of the foot. Increased contact pressures are generated in the plantar foot with weightbearing. The resultant overload of the ligaments and the intrinsic muscles of the midfoot and forefoot is manifest in a variety of pathologic processes. The altered mechanics contributes to, among other conditions, ankle impingement, plantar fasciitis, midfoot arthritis, posterior tibial tendon dysfunction, forefoot overload, diabetic ulceration, and Charcot arthropathy. Effective management of these conditions includes addressing the underlying gastrocnemius contracture as well as the related foot and ankle pathology. Here we describe the underlying biomechanical abnormalities and radiographic findings in these pathological conditions of the foot and ankle associated with gastroequinus contracture. An awareness and understanding of the pathomechanics should enable the radiologist to better appreciate the form and function associated with the image.     

Stabilometry is a predictor of gait performance in chronic hemiparetic stroke patients

In patients with spastic hemiparesis, centre of foot pressure (CoP) is shifted toward the unaffected limb during quiet stance. We hypothesised that abnormal gait features would correlate with the degree of asymmetry during stance. In 15 patients and 17 normals we recorded CoP and body sway by a force platform and measured spatial–temporal variables of gait with pedobarography. In patients CoP was shifted toward the unaffected limb and sway was larger than in normals. CoP position was associated with the decrease in strength of the affected lower-limb muscles. Spatio-temporal variables of gait were also affected by the disease. Cadence and velocity were decreased, duration of single support on the unaffected limb and of double support were increased with respect to normals. The degree of impairment of gait variables correlated with CoP. We found a negative relationship between velocity or cadence and CoP, and a positive relationship between duration of single support and CoP in the unaffected but not in the affected limb. Duration of double support correlated positively with CoP. CoP asymmetry during both standing and walking suggests that postural and gait problems share some common neural origin in hemiparetic patients. This asymmetry affects gait performance by increasing the time and effort needed to shift body weight toward the affected limb. The degree of postural asymmetry measured by stabilometry is associated with the level of impairment of gait variables.     

Pressure-relieving properties of various shoe inserts in older people with plantar heel pain

Plantar heel pain is one of the most common musculoskeletal conditions affecting the foot and it is commonly experienced by older adults. Contoured foot orthoses and some heel inserts have been found to be effective for plantar heel pain, however the mechanism by which they achieve their effects is largely unknown. The aim of this study was to investigate the effects of foot orthoses and heel inserts on plantar pressures in older adults with plantar heel pain. Thirty-six adults aged over 65 years with plantar heel pain participated in the study. Using the in-shoe Pedar(?) system, plantar pressure data were recorded while participants walked along an 8 m walkway wearing a standardised shoe and 4 different shoe inserts. The shoe inserts consisted of a silicon heel cup, a soft foam heel pad, a heel lift and a prefabricated foot orthosis. Data were collected for the heel, midfoot and forefoot. Statistically significant attenuation of heel peak plantar pressure was provided by 3 of the 4 shoe inserts. The greatest reduction was achieved by the prefabricated foot orthosis, which provided a fivefold reduction compared to the next most effective insert. The contoured nature of the prefabricated foot orthosis allowed for an increase in midfoot contact area, resulting in a greater redistribution of force. The prefabricated foot orthosis was also the only shoe insert that did not increase forefoot pressure. The findings from this study indicate that of the shoe inserts tested, the contoured prefabricated foot orthosis is the most effective at reducing pressure under the heel in older people with heel pain.     

The effect of foot type on in-shoe plantar pressure during walking and running

The purpose of this study was to determine if low arch feet have altered plantar loading patterns when compared to normal feet during both walking and running. Fifty healthy subjects (34 normal feet, 16 flat feet) walked and ran five trials each at standard speeds. In-shoe pressure data were collected at 50 Hz. Contact area, peak pressure, maximum force, and force-time integral were analyzed in eight different regions of the foot. Foot type was determined by examining navicular height, arch angle, rearfoot angle, and a clinical score. A series of 2 x 2 repeated measures ANOVAs were used to determine statistical differences (alpha<0.05). A significant interaction existed between foot type and movement type for the maximum force in the medial midfoot. Total foot contact area, maximum force and peak pressure were significantly increased during running. Contact area in each insole area, except for the rearfoot, was significantly increased during running. Peak pressure and maximum force were significantly increased during running in each of the foot regions. However, the force-time integral was significantly decreased during running in the rearfoot, lateral midfoot, middle forefoot, and lateral forefoot. Significant differences between foot types existed for contact area in the medial midfoot and maximum force and peak pressure in the lateral forefoot. The maximum force and peak pressures were significantly decreased for the flat foot type. Therefore, individuals with a flat foot could be at a lower risk for lateral column metatarsal stress fractures, indicating that foot type should be assessed when determining an individual's risk for metatarsal stress fractures.     

Estimation of a midfoot joint center in typically developed adults using functional calibration methods

BackgroundThere are detailed findings on hip and knee joint parameters determined via functional calibration methods for use in instrumented 3D-gait analysis but these methods have not yet been addressed to the foot.Research questionAre functional calibration methods feasible for determining foot joint parameters and may they help for clinical interpretation of foot deformities?MethodsRigid segments were formed by markers on forefoot and hindfoot via a least square method. The position of the midfoot joint articulating both foot segments was then determined via a functional calibration motion. This two-stage procedure was applied on a cohort of 17 typically developed adults and one subject with severe planovalgus foot deformity for determining the location of the midfoot joint and kinematics of hindfoot and forefoot.ResultsThe position of the midfoot joint center could be estimated in the typically developed cohort and also in the demonstration case with planovalgus foot deformity. Depending on the choice of marker set for hindfoot and forefoot, the position of the joint center varied in the anatomic midfoot region with most robust results when addressing the marker on the navicular to the hindfoot.ConclusionThe presented method for joint center determination within the foot and the characteristic results of the foot joint angles appear promising for typically developed feet. However, further validation of the method is needed for application in clinical context.     

Functional characterization of plantar pressure patterns in gait of typically developing children using dynamic pedobarography

BackgroundAbnormal foot posture is a common complaint presented in pediatric and pediatric orthopedic clinics. Functional, objective assessment of foot posture, with the potential for early identification of pathologic foot deformities, has, however, been lacking to date. While quantifying functional and regional impulses via dynamic pedobarography can improve the clinical assessment of children’s feet, normative values have not yet been reported or characterized.Research QuestionThe objectives of this study were to: (1) quantify and characterize the pattern and spectrum of foot impulses in walking-aged, typically developing children; and (2) compare these to impulses from non-disabled adults.MethodsFoot impulses of 102 participants (52 female) in five pre-determined age groups (2−3, 4–6, 7–10, 11−14, 15−17 years) were examined using dynamic pedobarography. Each pressure map (3 per foot per child) was divided according to anatomical foot regions: the hallux, heel, medial forefoot, lateral forefoot, lesser toes (D2 to D5), and midfoot. The impulse was calculated for each region and used to generate regional percent impulses and impulse ratios to assess anteroposterior and mediolateral balance within the foot.ResultsThe impulse through the midfoot was highest in the youngest age group, with a corresponding lower impulse through the medial forefoot. As age advanced, the midfoot impulse decreased (p = 0.001), and the forefoot balance shifted slightly more medially (%Medial Forefoot: p = 0.004; Medial-Lateral Forefoot Balance: p = 0.019). When compared to adults, there were no significant differences between 15−17 year old children and adults in any of the regional percent impulses and impulse ratios. This indicates that skeletal maturity of the foot by late adolescence results in functional characteristics seen in adults.SignificanceThe age-standardized norms of functional and regional impulse measures in children reported in this study can be used as a comparative benchmark in the clinical assessment of children presenting with various foot deformities.     

Comparison of plantar loads during running on different overground surfaces

The objective of this study is to compare plantar loads during running on different overground surfaces. Fifteen heel-to-toe runners participated in the study. Plantar load data were collected and analyzed using an insole sensor system during running on concrete, synthetic rubber, and grass surfaces at a running speed of 3.8 m/s. Compared with running on concrete surface, running on natural grass showed a lower magnitude of maximum plantar pressure at the total foot (451.8 kPa vs. 401.7 kPa, p = 0.016), lateral midfoot (175.3 kPa vs. 148.0 kPa, p?=?0.004), central forefoot (366.3 kPa vs. 336.8 kPa, p = 0.003), and lateral forefoot (290.2 kPa vs. 257.9 kPa, p = 0.004). Moreover, running on natural grass showed a longer relative contact time compared with running on a concrete surface at the central forefoot (81.9% vs. 78.8%, p = 0.017) and lateral forefoot (75.2% vs. 73.1%, p = 0.007). No significant difference was observed in other multiple comparisons. Different surfaces affected the plantar loads while running. The differences may help us to understand potential injury mechanisms.     

Balance control in peripheral neuropathy: Are patients equally unstable under static and dynamic conditions?

The aim of this investigation was to assess the potentially different effects of impaired proprioceptive input in balance control under static and dynamic conditions in neuropathic patients. We recruited 20 normal subjects and 27 patients affected by neuropathies known to affect to a different extent large and medium size afferent fibres. The patients comprised 5 with Charcot-Marie-Tooth disease type 1A (CMT1A), 8 with CMT type 2 (CMT2) and 14 with Diabetes polyneuropathy (Diabetics). Measurement of balance during quiet stance on a stabilometric platform showed that sway area (SA) was larger in the CMT2 and Diabetics than normal subjects or in CMT1A, under both eyes open and closed conditions. The estimated conduction velocity (CV) of the group II afferent fibres was lower in CMT2 and Diabetics than in normal subjects and CMT1A. Across all patients, SA increased as a function of the slowing of group II CV. During a dynamic balance task the head A-P displacement was only slightly increased in the patient groups with respect to normals, despite the increased delay at which the head followed displacement of the feet. The unpredictably good performance of all patient groups under dynamic condition, which was at variance with their imbalance during quiet stance, may indicate that these patients learnt to exploit anticipatory postural strategies.     

Immediate effect of visual,auditory and combined feedback on foot strike pattern

BackgroundA growing body of literature supports the promising effect of real-time feedback to re-train runners. However, no studies have comprehensively assessed the effects of foots trike and cadence modification using different forms of real-time feedback provided via wearable devices.Research questionThe purpose of the present study was to determine if a change could be made in foot strike pattern and plantar loads using real-time visual, auditory and combined feedback provided using wearable devices.MethodsVisual, auditory and combined feedback were provided using wearable devices as fifteen recreational runners ran on a treadmill at self-selected speed and increased cadence. Plantar loads and location of initial contact were measured with a flexible insole system. Repeated measures ANOVAs with Bonferroni adjusted pair-wise comparisons were used to assess statistical significance.Results and significanceA significant effect of condition was noted on location of center of pressure (p < 0.01). Bonferroni-adjusted post-hoc comparisons showed that feedback conditions differed from baseline as well as the new cadence conditions, however did not differ from each other. A significant interaction effect (region x feedback) was found for plantar loads (maximum force P < 0.001). Significant effects of feedback were noted at the heel (P < 0.001), medial midfoot (P < 0.001), lateral midfoot (P < 0.001), medial forefoot (P = 0.003), central forefoot (P = 0.003), and great toe (P = 0.004) but not at the lateral forefoot (P = 0.6) or lateral toes (P = 0.507).SignificanceThe unique findings of our study showed that an anterior shift of the center of pressure, particularly when foot strike modification was combined with 10% increased cadence. We found lower heel and midfoot loads along with higher forefoot and great toe loads when foot strike modification using real-time feedback was combined with increased cadence. Our findings also suggest that auditory feedback might be more effective than visual feedback in foot-strike modification.     

Understanding the role of foot biomechanics on regional foot orthosis deformation in flatfoot individuals during walking

BackgroundFoot orthoses (FOs) are one of the most common interventions to restore normal foot mechanics in flatfoot individuals. New technologies have made it possible to deliver customized FOs with complex designs for potentially better functionalities. However, translating the individuals’ biomechanical needs into the design of customized FOs is not yet fully understood.Research questionOur objective was to identify whether the deformation of customized FOs is related to foot kinematics and plantar pressure during walking.MethodsThe kinematics of multi-segment foot and FOs contour were recorded together with plantar pressure in 17 flatfoot individuals while walking with customized FOs. The deformation of FOs surface was predicted from its contour kinematics using an artificial neural network. Plantar pressure map and deformation were divided into five anatomically based regions defined by the corresponding foot segments. Forward stepwise linear mixed models were built for each of the four gait phases to determine the feet-FOs interaction.ResultsIt was observed that some associations existed between foot kinematics and pressure with regional FOs deformation. From heel-strike to foot-flat, longitudinal arch angle was associated with FOs deformation in forefoot. From foot-flat to midstance, rearfoot eversion accounted for variation in the deformation of medial FOs regions, and forefoot abduction for the lateral regions. From midstance to heel-off, rearfoot eversion, longitudinal arch angle, and plantar pressure played significant role in deformation. Finally, from heel-off to toe-off, forefoot adduction affected the deformation of forefoot and midfoot.SignificanceThis study provides guidelines for designing customized FOs. Flatfoot individuals with excessive rearfoot eversion or very flexible medial arches require more support on medial FOs regions, while the ones with excessive forefoot abduction need the support on lateral regions. However, a compromise should be made between the level of support and the level of increase in plantar pressure to avoid stress on foot structures.     

Increased plantar foot pressure in persons affected by leprosy

Although foot pressure has been reported to be increased in people affected by leprosy, studies on foot pressure and its determinants are limited. Therefore, the aim was to assess barefoot plantar foot pressure and to identify clinical determinants of increased plantar foot pressure in leprosy affected persons. Plantar pressure in both feet was assessed using the Novel EMED-X platform in 39 persons affected by leprosy. Peak pressure was determined for the total foot and four regions: hallux, metatarsal heads, midfoot and heel. Potential determinants were: age, weight, nerve function (Neuropathy Disability Score, Pressure Perception Threshold and Vibration Perception Threshold), toe and foot deformities, joint mobility, ankle muscle strength and callus. Increased peak pressure (>600kPa) was observed in 46% of the participants. The highest peak pressure (mean) was found in the metatarsal heads region (right 549 (SD 321)kPa; left 530 (SD 298)kPa). Multilevel regression analysis showed that Neuropathy Disability Score, amputation/absorption of toes and hallux valgus independently contributed to metatarsal heads peak pressure in persons affected with leprosy. To conclude, peak pressure is increased in people affected by leprosy. The highest peak pressure is found in the forefoot region and is significantly associated to Neuropathy Disability Score, toe amputation/absorption and hallux valgus. Screening for clinical characteristics can be used to identify individual persons affected by leprosy at risk of excessive pressure.     

The effect of a long-distance run on plantar pressure distribution during running

The purpose of this study was to assess plantar pressure alterations after long-distance running. Prior to and after a 20 km run, force distribution underneath the feet of 52 participants was registered using Footscan(?) pressure plates while the participants ran shod at a constant self-selected pace. Peak force, mean force and impulse were registered underneath different zones of the foot. In addition, temporal data as total foot contact time, time of contact and end of contact were derived for these zones. Furthermore, a medio-lateral pressure distribution ratio was calculated in different phases of the roll-off. After the run, increases in the loading of the forefoot, midfoot and medial heel were noted and decreases in loading of the lateral toes. In the forefoot push off phase a more lateral pressure distribution was observed. The results of this study demonstrated plantar pressure deviations after long-distance running which could give additional information related to several running injuries.     

Intrinsic foot muscles act to stabilise the foot when greater fluctuations in centre of pressure movement result from increased postural balance challenge

BackgroundIncreased postural balance challenge is associated with more fluctuations in centre of pressure movement, indicating increased interference from the postural control system. The role of intrinsic foot muscles in balance control is relatively understudied and whether such control system interference occurs at the level of these muscles is unknown.Research QuestionDo fewer fluctuations in intrinsic foot muscle excitation occur in response to increased postural balance challenge?MethodsSurface EMGs were recorded using a grid of 13 × 5 channels from the plantar surface of the foot of 17 participants, who completed three balance tasks: bipedal stance; single leg stance and bipedal tip-toe. Centre of pressure (CoP) movement was calculated from simultaneously recorded force plate signals. Fluctuations in CoP and EMGs for each task were quantified using a sample entropy based metric, Entropy Halflife (EnHL). Longer EnHL indicates fewer signal fluctuations.ResultsThe shortest EMG EnHL, 9.27 ± 3.34 ms (median ± interquartile range), occurred during bipedal stance and the longest during bipedal tip-toe 15.46 ± 11.16 ms, with 18.80 ± 8.00 ms recorded for single leg stance. Differences were statistically significant between bipedal stance and both bipedal tip-toe (p < 0.001) and single leg stance (p < 0.001). CoP EnHL for both anterior-posterior and medial-lateral movements also differed significantly between tasks (p < 0.001, both cases). However, anterior-posterior CoP EnHL was longest for bipedal stance 259.84±230.22 ms and shortest for bipedal tip-toe 146.25±73.35 ms. Medial-lateral CoP EnHL was also longest during bipedal stance 215.73±187.58 ms, but shortest for single leg stance 113.48±83.01 ms.SignificanceFewer fluctuations in intrinsic foot muscle excitation occur in response to increased postural balance challenge. Fluctuations in CoP movement during balance must be predominantly driven by excitation of muscles extrinsic to the foot. Intrinsic foot muscles therefore likely play a greater role in stabilisation of the foot than balance control during the postural tasks studied.