Toe Flexor Research Articles

Contributions of flexor hallucis longus and brevis muscles to isometric toe flexor force production

Purpose Morphological differences between the two primary great toe flexors – flexor hallucis longus (FHL) and flexor hallucis brevis (FHB) – likely drive differences in how these muscles contribute to functional toe flexion torque production. The aim of the study was to investigate FHL and FHB activation in two isometric toe flexion tasks – one called a “toe-pushing” task with the metatarsophalangeal (MTP) joints extended and the interphalangeal (IP) joints in neutral and another called a “toe-gripping” task with the MTP joints in neutral and flexed IP joints. Methods Twenty participants’ FHL and FHB muscles were instrumented with intramuscular electromyography electrodes. Muscle activation was normalized to a maximum voluntary contraction and compared between the two isometric toe flexor force production tasks. Results Overall, participants utilized these two toe flexors completely differently in the two tasks. In the toe-gripping task, the FHL was activated to a much greater extent than the FHB. In fact, 18 our of 20 participants activated FHL at more than seventy percent maximum voluntary contraction and half of participants activated FHB at less than ten percent. In contrast, muscle activation during the toe-pushing task appeared more reliant on the FHB for most participants. Conclusions Different contributions from the FHL and FHB to toe flexor force production in these two tasks are potentially driven by differences in muscle functional length among other factors. These findings help to inform the selection of rehabilitation and training exercises meant to preferentially target intrinsic or extrinsic foot musculature.

Botulinum toxin-A injection improves motor recovery in patients with stroke

Aim: Spasticity that occurs after a stroke may contribute to disability. Botulinum toxin type-A (BTX-A) injections are commonly used to manage spasticity. This study sought to determine the effectiveness of BTX-A injections on spasticity and motor recovery in patients with stroke. Materials and Methods: Twenty-five patients with stroke scheduled for BTX-A injection for spasticity were included in the study. The patients were analyzed in two groups: upper limb and lower limb group. A single dose of BTX-A was applied to the patients. Before, 2, and 12 weeks after BTX-A injections, motor function was assessed using Brunnstrom recovery stages, and spasticity was evaluated according to Modified Ashworth Scale (MAS). The lower limb group additionally underwent the Functional Ambulation Classification (FAC) and 10-meter walking test. Results: Mean age of patients was 54.96 ± 12.84 years. Eighteen patients were enrolled in the upper limb group and 23 in the lower limb group. Clinical evaluation of the upper limb group two weeks after injections demonstrated a significant decrease in shoulder adductor muscle MAS, elbow, wrist, and finger flexor muscles MAS, and a significant improvement in Brunnstrom recovery stages for the upper limb and hand (p<0.05). At week 12, spasticity decreased only for the shoulder adductor muscles. In the lower limb group, clinical evaluation at week 2 showed a decrease in the knee extensor and toe flexor muscles MAS. Assessment of the patients at week 12 found a significant improvement in Brunnstrom recovery stage for the lower limbs (p<0.05). There was no statistically significant recovery in the FAC and 10-meter walking test (p>0.05). Conclusion: This study supports that BTX-A injections are effective for improving spasticity and motor function in patients with stroke.

REPERCURSSÕES DO TREINO DE RESISTÊNCIA DO CORE SOBRE O DESEMPENHO DOS JOGADORES DE FUTEBOL

ABSTRACT Introduction: Soccer players are athletes who need to develop advanced characteristics of strength and speed. The resistance training of the muscles involved in the core is a new training theory applicable to modern sports that is gaining prominence due to its amazing results. It is of great value for researchers to integrate the strengths of core strengthening into soccer training, improve their protocols, and compensate for their limitations. Objective: This study aimed to analyze the relationship between core strength training and physical conditioning in soccer players. At the same time, this article discusses the influence of core muscle strength characteristics on athletes’ physical performance. Methods: This article selects advanced soccer players as research subjects. Volunteers were randomly divided into two groups (control and experimental groups). The experimental group received core muscle strength training, while the control group received daily training. This paper analyzed the muscle strength characteristics of the two groups of volunteers. Then, this paper conducts a statistical and mathematical analysis of the muscle strength level data in two groups of athletes. Results: The experimental group showed significant differences in bilateral hip and ankle joint flexors after core muscle strength training (P<0.01). The relative peak moment of flexion and extension of the left hip was lower than that of the right hip, a factor justified by the predominant motor laterality principle on the players. The muscle strength of the left knee and ankle joints was greater than that of the right. Both experimental and control groups showed that the strength of the ankle flexors was better than the ankle extensors (knee toe flexors). The data were very significantly different (P<0.01). Conclusion: Muscular endurance training can help improve the physical conditioning of soccer players. Athletes can reinforce core strength training in their daily training. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Investigation of the Relationship Between the Morphology of the Toe Flexor Muscles in Ballet Dancers and the Postural Stability During Standing on Demi-Pointe: A Cross-Sectional Study.

This study investigated how toe flexor muscles are related to postural stability in 11 ballet dancers and 12 non-dancers.<br/> 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.<br/> 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).<br/> 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.

Relationship between foot morphology, muscle strength, and physical performance test in women aged 65 years and older: a cross-sectional study

BackgroundHallux valgus is a foot deformity that may affect gait, thus increasing the risk of falls among older people. We investigated the relationship between foot morphology, muscle strength, and physical performance.MethodsIn this study, community-dwelling older people aged ≥65 years were included. A three-dimensional footprint automatic measurement apparatus was used to measure the hallux valgus angle, arch height ratio, and heel-floor angle. Furthermore, the toe flexor strength and ankle plantar flexion strength were measured. Physical performance tests included the five-repetition sit-to-stand test, one-leg standing time, maximal step length, functional reach test, and 5-m fastest walking time (walking time). The relationship between the hallux valgus angle and foot morphology and muscle strength was examined. In addition, factors affecting physical performance testing were assessed. Two-group comparisons, correlation, and multiple comparisons were used for statistical analyses.ResultsOf the 133 women (age 77.7 ± 6.2 years), 57 had hallux valgus and 76 had no hallux valgus. There was a significant difference in the arch height ratio and heel-floor angle between women with and without hallux valgus (p < 0.001). A correlation was found between the hallux valgus angle and the heel-floor angle (r = 0.468, p < 0.001) and arch height ratio (r = − 0.337, p < 0.001), respectively. Multiple regression analysis showed that the hallux valgus angle was related to functional reach (β = − 0.162, p = 0.042), and toe flexor strength was related to five-repetition sit-to-stand (β = − 0.182, p = 0.036), maximal step length (β = 0.328, p < 0.001), and walking time (β = − 0.219, p = 0.006).ConclusionsA relationship was found between the hallux valgus angle, arch height rate, and inward inclination angle of the calcaneus. Functional reach was predicted based on the hallux valgus angle, whereas the five-repetition sit-to-stand, maximal step length, and walking time were predicted based on toe flexor strength. Hallux valgus predicted not only the forefoot but also the foot morphology and was related to physical performance. From the perspective of motor function and fall prevention, efforts should be made to better understand and prevent the onset and progression of hallux valgus.

Effects of intervention combining transcranial direct current stimulation and foot core exercise on sensorimotor function in foot and static balance

ObjectiveThis study aimed to examine the effects of combining transcranial direct current stimulation (tDCS) and foot core exercise (FCE) on the sensorimotor function of the foot (i.e., toe flexor strength and passive ankle kinesthesia) and static balance.MethodsIn this double-blinded and randomized study, 30 participants were randomly assigned into two groups: tDCS combined with FCE and sham combined with FCE (i.e., control group). The participants received 2 mA stimulation for 20 min concurrently with FCE over 4 weeks (i.e., three sessions per week). After the first two groups completed the intervention, a reference group (FCE-only group) was included to further explore the placebo effects of sham by comparing it with the control group. Foot muscle strength, passive ankle kinesthesia, and static balance were assessed at baseline and after the intervention.ResultsCompared with the control group and baseline, tDCS combined with FCE could increase toe flexor strength (p < 0.001) and decrease the passive kinesthesia threshold of ankle eversion (p = 0.002). No significant differences in static balance were observed between tDCS + FCE and control groups. The linear regression models showed an association towards significance between the percent changes in metatarsophalangeal joint flexor strength and the anteroposterior average sway velocity of the center of gravity in one-leg standing with eyes closed following tDCS + FCE (r2 = 0.286; p = 0.057). The exploratory analysis also showed that compared with FCE alone, the sham stimulation did not induce any placebo effects during FCE.ConclusionParticipating in 4 weeks of intervention using tDCS in combination with FCE effectively enhances toe flexor strength and foot–ankle sensory function.

Effects of 4Weeks of High-Definition Transcranial Direct Stimulation and Foot Core Exercise on Foot Sensorimotor Function and Postural Control.

Objective: This study aimed to examine the effects of 4 weeks of high-definition transcranial direct current stimulation (HD-tDCS) and foot core exercise (FCE) on foot sensorimotor function (i.e., toe flexor strength and passive ankle kinesthesia) and postural control. Methods: In total, 36 participants were randomly assigned into three groups as follows: HD-tDCS, FCE, and the control group. A total of 12 training sessions were performed over 4 weeks (i.e., three sessions per week) in the laboratory. The HD-tDCS group received 20-min HD-tDCS with a current density of 2 mA, and the FCE group completed short foot exercise, towel curls, toe spread and squeeze, and balance board training. Participants in the control group just maintained the activities what they usually did and did not receive any interventions. Foot muscle strength, passive ankle kinesthesia, and postural control were assessed at baseline and post-intervention. Results: HD-tDCS induced a greater decrease in the percentage changes in the passive kinesthesia thresholds of ankle inversion (p < 0.001) and eversion (p = 0.013) than the control group. Compared with the control group, a significant increase in the percentage change in the metatarsophalangeal joint flexor strength was found in the HD-tDCS group (p = 0.008) and the FCE group (p = 0.027), and a significant increase in the percentage change in toe flexor strength was observed in the FCE group (p = 0.015). Moreover, FCE induced a greater reduction in the percent changes in the medial–lateral average center of gravity sway velocity in one-leg standing with eyes open (p = 0.033) and the anteroposterior average center of gravity sway velocity in one-leg standing with eyes closed (p < 0.001) than control. Conclusion: This study demonstrated that 4 weeks of HD-tDCS and FCE induced distinct benefits on foot sensorimotor function and the standing postural control performance in healthy young adults. HD-tDCS could improve the metatarsophalangeal joint flexor strength and the passive kinesthesia thresholds of ankle inversion and eversion. Meanwhile, FCE could also enhance foot muscle strength and enhance postural control performance in one-leg standing.

The mechanical role of the metatarsophalangeal joint in human jumping.

This study investigated the mechanical role of metatarsophalangeal (MTP) joints in human jumping. Eighteen healthy young men performed three types of single-leg jumps (SJ: squat jump; CMJ: countermovement jump; HJ: standing horizontal jump) on a force plate under barefoot (BARE) and forefoot immobilisation (FFIM) conditions. For FFIM, the forefoot was immobilised around the MTP joints of the dominant leg by a custom-made splint. Force-time components and the centre of pressure (COP) trajectory were measured from the ground reaction force (GRF) in the take-off phase of jumping. The vertical jump heights calculated from the net vertical impulse were lower under FFIM than under BARE during the CMJ (p < 0.05). The HJ distance under FFIM was significantly shorter than that under BARE (p < 0.01). The relative net vertical impulse was lower under FFIM than under BARE during the CMJ (p < 0.05). During the HJ, all the horizontal GRF variables were significantly lower under FFIM than under BARE (p < 0.01), but none of the vertical GRF variables differed between the two conditions. The horizontal relative GRF in the 90–95% of the final take-off phase during the HJ was significantly lower under FFIM than under BARE (p < 0.01). Under FFIM, the COP range in the antero-posterior direction in the take-off phase of the HJ decreased (p < 0.05), whereas its range in the anterior direction for the SJ and CMJ increased (p < 0.05). The results of this study indicate that MTP joint motion can play an important role in regulating force-generating capacities of toe flexor muscles in the take-off phase of human jumping, especially in the horizontal direction of horizontal jumping.

Contributions of Intrinsic and Extrinsic Foot Muscles during Functional Standing Postures.

Purpose Maintaining balance during static standing postures requires the coordination of many neuromuscular mechanisms. The role of the intrinsic and extrinsic foot muscles in this paradigm has yet to be clearly defined. The purpose of this study was to explore foot muscle activation during static phases on common weight-bearing tasks of varying loads and balance demands. Methods Twenty healthy young adults performed 6 standing postures (single-limb and double-limb stand, squat, and heel raise) with one foot on a force plate. Muscle activity was recorded from the abductor hallucis, flexor hallucis longus and brevis, and tibialis posterior using intramuscular electrodes; surface electrodes were used to record activity from the peroneus longus and tibialis anterior. Two-way repeated measures ANOVA (2 loading conditions × 3 postures) were run to compare muscle activation and center of pressure velocity. Results Intrinsic foot muscle activity increased as loading and postural demand increased; however, the specific effects varied for each of the extrinsic foot muscles. Conclusions These results suggest that the intrinsic foot muscles play an important role in maintaining static balance. Strengthening intrinsic and extrinsic foot muscles may help increase stability in people who have weak toe flexors or who suffer from a variety of foot pathologies.

Toe flexion movement with tendon excursion based on anatomical variation: A cadaver study

Background/Purpose To investigate the relationship between anatomical variation of the toe flexor muscles and the resulting variation of toe flexion angle from tendon excursion. Methods Six cadaveric lower extremities preserved by Thiel’s embalming method were evaluated. The toe flexor muscles were distracted individually and toe flexion angles measured. The anatomic variation were observed by gross anatomical dissection. Results The toes with tendinous slips of flexor hallucis longus (FHL) showed similar flexion angles between the FHL and flexor digitorum longus. However, there were differences observed regarding toe flexion and tendon excursion of the flexor digitorum muscle and quadratus plantae due to the anatomic variations. Conclusion The anatomical variation of the toe flexor muscles should be taken into account when evaluating toe function and applying exercise therapy for foot disorders.

Increased toe flexor strength does not relate to altered postural sway during static upright standing after 12 weeks of multicomponent exercise training

ABSTRACT 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.

Evaluating the Function of the Foot Core System in the Elderly.

As a complex structure to link the body and the ground, the foot contributes to postural control in human static and dynamic activities. The foot core is rooted in the functional interdependence of the passive, active, and neural subsystems, which combine into the foot core system controlling foot motion and stability. The foot arch (passive subsystem), responsible for load, is considered the functional core of the foot, and its stability is necessary for normal foot functions. The functional abnormalities of the foot have been widely reported in the elderly, such as weakness of toe flexor muscles, abnormal foot postures, and decreased plantar sensory sensitivity. In this paper, a comprehensive approach is introduced for evaluating the foot function based on foot core subsystems. The strength and morphology of the foot intrinsic and extrinsic muscles were used to evaluate the foot muscle (active subsystem) function. The doming strength test was applied to determine the function of foot intrinsic muscles, while the toe flexion strength test focused more on the function of extrinsic muscles. The navicular drop test and foot posture index were applied to evaluate foot arch (passive subsystem) function. For the neural subsystem, the plantar light touch threshold test and two-point discrimination test were used to assess plantar tactile sensitivity at nine regions of the foot. This study provides new insights into the foot core function in the elderly and other populations.

Associations between the size of individual plantar intrinsic and extrinsic foot muscles and toe flexor strength

BackgroundThe 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.MethodsIn 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 (ACSAmax) 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.ResultsTFS was significantly associated with the ACSAmax 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 ACSAmax and MV (p = 0.189). Stepwise multiple linear regression analysis indicated that ACSAmax and MV of the ADDH-OH alone explained 42 and 29%, respectively, of the variance in TFS.ConclusionThe 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.

Foot arch height, toe flexor strength, and dynamic balance ability in collegiate female dancers and non-dancers.

[Purpose] To characterize the foot arch height, toe flexor strength, and dynamic balance ability of collegiate female dancers and age-matched non-dancers. [Participants and Methods] This study included 20 healthy college-aged female dancers (21.6 ± 0.8 years) and 20 age-matched females (19.7 ± 1.0 years) with no previous experience in sports as non-dancers. Foot arch height was determined by measuring the height of the navicular tuberosity in the standing position using a ruler. Toe flexor strength was measured while seated on a chair using a toe grip dynamometer. Dynamic balance ability was evaluated based on the reach distance measured using a professional Y-balance test kit. [Results] The collegiate dancers had higher foot arches, greater toe flexor strength, and longer Y-balance test reach distance than the non-dancers. [Conclusion] The foot arch height, toe flexor strength, and dynamic balance ability of collegiate female dancers were adapted through years of training and were superior to those of non-dancers.

Effectiveness of Plantar and Toe Flexor Movement in Warm-Up

Effectiveness of Plantar and Toe Flexor Movement in Warm-Up

The long-term effects of wearing moderate minimalist shoes on a child’s foot strength, muscle structure and balance: A randomised controlled trial

BackgroundFrom retrospective research, it is believed that children who predominantly spend their time shod have poorer foot strength and performance than those who are predominantly barefoot. Children’s foot motion has been shown to be adversely affected by standard school shoes; however, the long-term effect of moderate minimalist shoes on foot strength, muscle structure and balance in children is unknown. Research questionDoes wearing moderate minimalist shoes, compared to stiff shoes, benefit a child’s foot strength, muscle structure and performance over time? MethodsSeventy healthy children (9–12 yr) were randomly assigned to wear standard (control), or minimalist shoes (experimental) at school, for nine months. Cross-sectional areas (CSA) of Abductor Hallucis (AH) and Flexor Digitorum Brevis (FDB) muscles, and toe flexor strength (TFS) of hallux and lesser toes separately, were primary outcome measures. Single leg balance (SLB), Y-balance test (YBT) and standing long jump (SLJ) were secondary outcome measures. Pre- and post-intervention measurements were analysed for between group differences with ANCOVA. ResultsMinimalist shoes resulted in moderate but statistically non-significant increases in muscle CSA (AH η2p =.04, FDB η2p =.05) and TFS (hallux η2p =.05, lesser toes η2p =.04). Significant moderate to large improvements in YBT in the experimental group were found in the postero-medial (P = .04, η2p =.07) and postero-lateral (P = .01, η2p =.10) directions. YBT (anterior, postero-medial and postero-lateral) was correlated with hallux TFS (R =.29,.27 and.33 respectively), lesser toes TFS (R =.28,.35 and.38 respectively) and SLJ (R =.30,.39 and.57 respectively). CSA of FDB was correlated with SLJ (R =.34) and SLB (R =.42). SignificanceWearing moderate minimalist shoes long-term improves balance in children. TFS is correlated with better balance and SLJ. Moderate minimalist school shoes are recommended for children.

How Important is the Big Toe?: Functional Anatomy of Hallux Flexion

Introduction Bipedalism is a unique characteristic of homo sapiens allowing us the ability to stand and walk. Many muscles required for bipedalism have been studied with a focus on large superficial leg muscles. However, the functional anatomy of deeper muscles with unique foot function have not been explored. The flexor hallucis longus (FHL) of the posterior leg and flexor hallucis brevis (FHB) of the foot function to flex the big toe, are required for optimal locomotion, and have an important role in upright balance and gait. Furthermore, the FHL has been used in tendon transfers such as Achilles reconstruction. The loss of function of the FHL, including impairments in balance and walking, have been noted but not comprehensively explored. Thus, the purpose of this study was to assess the relative activation of these muscles (FHL and FHB) in toe flexion and postural movements by using indwelling electromyography (EMG) recordings. Methods In six healthy participants to date (4 males and 2 females) ages 22-25 years, indwelling fine wires were inserted into each of the following muscles of the dominant limb: FHL, FHB, soleus and tibialis anterior (TA), to record intramuscular EMG activity. Ultrasound imaging was used to ensure optimal placement of the fine wires within each muscle. After two familiarization sessions, participants were placed in a custom-built toe dynamometer to record maximal voluntary contractions (MVC) of the big toe flexors (ankle, knee, and hip were maintained at 90 degrees). Additionally, plantar flexion and dorsiflexion MVCs were recorded using a custom ankle dynamometer. Participants were then asked to perform functional tasks including standing quietly for 60 seconds, sitting and standing from a seated position, bilateral calf-raises, standing on one foot, and swaying anteriorly to their limit of stability (before requiring a step to stop falling). Data were analyzed offline using Spike2 software. EMG (root mean squared – RMS) activity from the various tasks for each muscle was normalized to the maximal EMG obtained from the MVC tasks and expressed as a percentage (%). Results Average toe flexion strength was ~174N of force. When standing on two feet the FHL was ~1% active relative to its MVC while the FHB was ~6% active. During sitting and standing from the seated position the FHL had ~3% activity while the FHB had ~10%. FHL and FHB had ~36% and 39% activity, respectively, during the body weight calf raise. When standing on one foot the FHL was ~6% active while the FHB was ~30% active. The greatest activity for these muscles within the functional tasks was during the anterior forward tilt with ~50% and 75% for the FHL and FHB, respectively. While performing toe flexion MVCs there was ~65% co-activation in the TA and ~4% in the soleus. Conclusion These results illustrate the importance of the FHL and FHB during balance (forward sway) compared with their activity during plantar flexion and other tasks, although the FHB was more active in these than the FHL. The large degree of co-activation in the TA to optimize toe flexion illustrates an important synergy required for optimal toe and foot function. In addition to providing a better understanding of the functional anatomy and biomechanics of the foot, these results also indicate consideration of the functional relevance of these big toe muscles in clinical interventions.

Intrinsic foot muscle hardness is related to dynamic postural stability after landing in healthy young men

BackgroundThe human foot has competent mechanisms for supporting weight and adapting movement to various surfaces; in particular, the toe flexor muscles aid in supporting the foot arches and may be important contributors to postural stability. However, the role of intrinsic foot muscle morphology and structure in the postural control system remains unclear, and the relationship between them is not well known. Research questionAre intrinsic foot muscle morphology and toe flexor strength related to static and dynamic postural stability in healthy young men?. MethodsA total of 27 healthy men aged 19–27 years participated in this study. intrinsic foot muscle morphology included muscle hardness and thickness. Cross-sectional area was measured by ultrasonography at an ankle dorsiflexion angle of 0°. The hardness of the abductor hallucis (AbH), flexor hallucis brevis, and flexor digitorum brevis (FDB) muscles was measured using ultrasound real-time tissue elastography. Static postural stability during single-leg standing on a single force platform with closed eyes was assessed for the right leg. In the assessment of dynamic postural stability, the subjects jumped and landed on single-leg onto a force platform and the dynamic postural stability index (DPSI) was measured. ResultsFDB muscle thickness showed a positive correlation with anteroposterior stability index (APSI) (r = 0.398, p = 0.040). AbH muscle hardness was negatively correlated with APSI (r = −0.407, p = 0.035); whereas FDB muscle hardness was positively correlated with DPSI (r = 0.534, p = 0.004), vertical stability index (r = 0.545, p = 0.003), and maximum vertical ground reaction force (r = 0.447, p = 0.020). Multiple regression with forced entry revealed that only DPSI was significantly correlated with FDB muscle hardness (p = 0.003). SignificanceThe results indicated that intrinsic foot muscle hardness plays an important role in dynamic postural control among healthy young men, which may enable a more rapid muscular response to changes in condition during jump landing and better performance in balance tasks.

Excellent reliability of toe strength measurements in children aged ten to twelve years achieved with a novel fixed dynamometer

BackgroundStronger 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 questionsDoes 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? MethodsTwo 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. ResultsThe 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). SignificanceThe fixed HHD protocol described in this study has excellent reliability for the test-retest evaluation of children’s toe flexor strength.

Differences in toe flexor strength and foot morphology between wheelchair dependent and ambulant older people in long-term care: a cross-sectional study

BackgroundHallux valgus, lesser toe deformity, and muscle weakness of the toe flexors contribute to falls in older people. This study aimed to examine the differences in toe flexor strength and foot morphology in older people requiring long-term care due to changes in the way they mobilize in everyday life.MethodsThis study included 84 people aged ≥70 years without motor paralysis who underwent rehabilitation. They were divided into those who could mobilize without a wheelchair (walking group, n = 54) and those who used a wheelchair to mobilize (wheelchair group, n = 30). The presence or absence of diseases was confirmed, and hand grip strength, toe flexor strength, and foot morphology using the foot printer were measured. The presence of diseases, hand grip strength, toe flexor strength, and foot morphology were compared between the two groups. Multiple logistic analysis was performed with wheelchair dependence as the dichotomous outcome variable, and the percentages of each strength measure observed in the wheelchair group to the average hand grip and toe flexor strength measures in the walking group were compared.ResultsNo significant between-group difference in foot morphology was found. The factors related to the differences in ways of ambulating in daily life were history of fracture, heart disease, and toe flexor strength. After comparing the muscle strength of the wheelchair group with the mean values of the walking group, we found that the toe flexor strength was significantly lower than the hand grip strength.ConclusionsOlder people who used a wheelchair to mobilize have significantly less toe flexor strength than those who do not despite no significant difference in foot morphology. Use of a wheelchair is associated with a reduction in toe flexor strength.