Electromyographic Studies of the Human Foot: Experimental Approaches to Hominid Evolution

Foot & Ankle ◽  
1983 ◽  
Vol 3 (6) ◽  
pp. 391-407 ◽  
Author(s):  
Lori A. Reeser ◽  
Randall L. Susman ◽  
Jack T. Stern
Keyword(s):  
Hominid Evolution ◽  
Abductor Hallucis ◽  
Early Hominid ◽  
Human Foot ◽  
Flexor Digitorum Brevis ◽  
Experimental Approaches ◽  
Arch Support ◽  
Flexor Digitorum ◽  
Hominid Fossils ◽  
Electromyographic Investigation

Theories about the functions of the foot muscles have centered on their role in arch support. Previous anatomical and electromyographic studies (reviewed herein) have demonstrated that the arches are normally maintained by bones and ligaments. This study reports an electromyographic investigation of five foot muscles (flexor digito-rum longus, flexor digitorum brevis, flexor accessorius, abductor hallucis, and abductor digiti quinti) conducted on four humans. The three toe flexors act together to resist extension of the toes during the stance phase of locomotion. Despite the large flexor accessorius in humans, neither this muscle nor the flexor digitorum brevis are preferentially recruited over the flexor digitorum lon-gus for any normal posture or locomotion. The abductors affect the mediolateral distribution of pressure by positioning the forefoot. We suggest that the foot muscles play an important role in positioning of the forces on the foot in both posture and locomotion. Future electromyographic experiments on human and ape foot muscles in conjunction with detailed studies of early hominid fossils promise to elucidate the pathways of human locomotor evolution.

scholarly journals The foot is more than a spring: human foot muscles perform work to adapt to the energetic requirements of locomotion

2019 ◽  
Vol 16 (150) ◽  
pp. 20180680 ◽  
Author(s):  
Ryan Riddick ◽  
Dominic J. Farris ◽  
Luke A. Kelly
Keyword(s):  
Net Energy ◽  
Centre Of Mass ◽  
Abductor Hallucis ◽  
Human Foot ◽  
Plantar Muscle ◽  
Elastic Mechanism ◽  
Intrinsic Foot Muscles ◽  
Flexor Digitorum Brevis ◽  
Energy Sink ◽  
Flexor Digitorum

The foot has been considered both as an elastic mechanism that increases the efficiency of locomotion by recycling energy, as well as an energy sink that helps stabilize movement by dissipating energy through contact with the ground. We measured the activity of two intrinsic foot muscles, flexor digitorum brevis (FDB) and abductor hallucis (AH), as well as the mechanical work performed by the foot as a whole and at a modelled plantar muscle–tendon unit (MTU) to test whether these passive mechanics are actively controlled during stepping. We found that the underlying passive visco-elasticity of the foot is modulated by the muscles of the foot, facilitating both dissipation and generation of energy depending on the mechanical requirements at the centre of mass (COM). Compared to level ground stepping, the foot dissipated and generated an additional –0.2 J kg −1 and 0.10 J kg −1 (both p < 0.001) when stepping down and up a 26 cm step respectively, corresponding to 21% and 10% of the additional net work performed by the leg on the COM. Of this compensation at the foot, the plantar MTU performed 30% and 89% of the work for step-downs and step-ups, respectively. This work occurred early in stance and late in stance for stepping down respectively, when the activation levels of FDB and AH were increased between 69 and 410% compared to level steps (all p < 0.001). These findings suggest that the energetic function of the foot is actively modulated by the intrinsic foot muscles and may play a significant role in movements requiring large changes in net energy such as stepping on stairs or inclines, accelerating, decelerating and jumping.

scholarly journals Shoes alter the spring-like function of the human foot during running

2016 ◽  
Vol 13 (119) ◽  
pp. 20160174 ◽  
Author(s):  
Luke A. Kelly ◽  
Glen A. Lichtwark ◽  
Dominic J. Farris ◽  
Andrew Cresswell
Keyword(s):  
Muscle Activation ◽  
Running Economy ◽  
Abductor Hallucis ◽  
Foot Kinematics ◽  
Human Foot ◽  
Running Shoes ◽  
Intrinsic Foot Muscles ◽  
Flexor Digitorum Brevis ◽  
Flexor Digitorum ◽  
Intramuscular Electromyography

The capacity to store and return energy in legs and feet that behave like springs is crucial to human running economy. Recent comparisons of shod and barefoot running have led to suggestions that modern running shoes may actually impede leg and foot-spring function by reducing the contributions from the leg and foot musculature. Here we examined the effect of running shoes on foot longitudinal arch (LA) motion and activation of the intrinsic foot muscles. Participants ran on a force-instrumented treadmill with and without running shoes. We recorded foot kinematics and muscle activation of the intrinsic foot muscles using intramuscular electromyography. In contrast to previous assertions, we observed an increase in both the peak (flexor digitorum brevis +60%) and total stance muscle activation (flexor digitorum brevis +70% and abductor hallucis +53%) of the intrinsic foot muscles when running with shoes. Increased intrinsic muscle activation corresponded with a reduction in LA compression (−25%). We confirm that running shoes do indeed influence the mechanical function of the foot. However, our findings suggest that these mechanical adjustments are likely to have occurred as a result of increased neuromuscular output, rather than impaired control as previously speculated. We propose a theoretical model for foot–shoe interaction to explain these novel findings.

scholarly journals Congenital Unilateral Hypertrophy of the Plantar Musculature with Multiple Toe Deformities: A Case Report and Literature Review

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Matthias Holzbauer ◽  
Stefan Rick ◽  
Marco Götze ◽  
Sébastien Hagmann
Keyword(s):  
Rare Case ◽  
Muscle Hypertrophy ◽  
Rare Condition ◽  
Abductor Hallucis ◽  
Claw Toe ◽  
Flexor Digitorum Brevis ◽  
Abductor Digiti Minimi ◽  
Fifth Toe ◽  
Flexor Digitorum ◽  
Toe Deformity

Congenital unilateral hypertrophy of the plantar musculature is a rare condition, and to our knowledge, reports of only 14 cases have been previously published. As only one describes a concomitant orthopedic toe deformity, we report our case of abductor hallucis, flexor digitorum brevis, and abductor digiti minimi muscle hypertrophy in combination with hallux valgus and claw toe deformity as well as a laterally abducted fifth toe. Thus, this report presents the rare case of congenital hypertrophy of the plantar musculature associated with complex toe deformities. Moreover, the present article contains a detailed description of our surgical technique as well as a review of the current literature.

scholarly journals Stepping onto the unknown: reflexes of the foot and ankle while stepping with perturbed perceptions of terrain

2021 ◽  
Vol 18 (176) ◽  
pp. 20210061
Author(s):  
R. C. Riddick ◽  
D. J. Farris ◽  
A. G. Cresswell ◽  
A. D. Kuo ◽  
L. A. Kelly
Keyword(s):  
Short Latency ◽  
The Body ◽  
Reflex Response ◽  
Abductor Hallucis ◽  
Muscle Dynamics ◽  
Contact Kinematics ◽  
Ankle Muscle ◽  
Level Information ◽  
Flexor Digitorum Brevis ◽  
Flexor Digitorum

Unanticipated variations in terrain can destabilize the body. The foot is the primary interface with the ground and we know that cutaneous reflexes provide important sensory feedback. However, little is known about the contribution of stretch reflexes from the muscles within the foot to upright stability. We used intramuscular electromyography measurements of the foot muscles flexor digitorum brevis (FDB) and abductor hallucis (AH) to show for the first time how their short-latency stretch reflex response (SLR) may play an important role in responding to stepping perturbations. The SLR of FDB and AH was highest for downwards steps and lowest for upwards steps, with the response amplitude for level and compliant steps in between. When the type of terrain was unknown or unexpected to the participant, the SLR of AH and the ankle muscle soleus tended to decrease. We found significant relationships between the contact kinematics and forces of the leg and the SLR, but a person's expectation still had significant effects even after accounting for these relationships. Motor control models of short-latency body stabilization should not only include local muscle dynamics, but also predictions of terrain based on higher level information such as from vision or memory.

Intrinsic Foot Muscle Morphology in Active Runners With and Without a History of Exercise-Related Lower Leg Pain

2020 ◽  
Vol 25 (2) ◽  
pp. 62-67
Author(s):  
Aliza K. Nedimyer ◽  
Brian G. Pietrosimone ◽  
Brittney A. Luc-Harkey ◽  
Erik A. Wikstrom
Keyword(s):  
Visual Information ◽  
Morphological Characteristics ◽  
Lower Leg ◽  
Leg Pain ◽  
Abductor Hallucis ◽  
Flexor Digitorum Brevis ◽  
History Of ◽  
Lower Leg Pain ◽  
Flexor Digitorum ◽  
Intrinsic Muscles

Our objective was to quantify the functional and morphological characteristics of the plantar intrinsic muscles in those with and without a history of exercise-related lower leg pain (ERLLP). Thirty-two active runners—24 with a history of ERLLP—volunteered. Strength of the flexor hallucis brevis and flexor digitorum brevis, postural control, and navicular drop were recorded. Morphology of the abductor hallucis, flexor digitorum brevis, and flexor hallucis brevis muscles were captured using ultrasonography. Those with ERLLP had smaller flexor hallucis brevis morphology measures (p ≤ .015) and a greater reliance on visual information while balancing (p = .05). ERLLP appears to alter intrinsic muscle function and morphology.

scholarly journals Intrinsic foot muscles contribute to elastic energy storage and return in the human foot

2019 ◽  
Vol 126 (1) ◽  
pp. 231-238 ◽  
Author(s):  
Luke A. Kelly ◽  
Dominic J. Farris ◽  
Andrew G. Cresswell ◽  
Glen A. Lichtwark
Keyword(s):  
Central Nervous System ◽  
Energy Storage ◽  
Elastic Energy ◽  
Mechanical Energy ◽  
Plantar Aponeurosis ◽  
Human Foot ◽  
Intrinsic Foot Muscles ◽  
Flexor Digitorum Brevis ◽  
The Central Nervous System ◽  
Flexor Digitorum

The human foot is uniquely stiff to enable forward propulsion, yet also possesses sufficient elasticity to act as an energy store, recycling mechanical energy during locomotion. Historically, this dichotomous function has been attributed to the passive contribution of the plantar aponeurosis. However, recent evidence highlights the potential for muscles to modulate the energetic function of the foot actively. Here, we test the hypothesis that the central nervous system can actively control the foot’s energetic function, via activation of the muscles within the foot’s longitudinal arch. We used a custom-built loading apparatus to deliver cyclical loads to human feet in vivo, to deform the arch in a manner similar to that observed in locomotion. We recorded foot motion and forces, alongside muscle activation and ultrasound images from flexor digitorum brevis (FDB), an intrinsic foot muscle that spans the arch. When active, the FDB muscle fascicles contracted in an isometric manner, facilitating elastic energy storage in the tendon, in addition to the energy stored within the plantar aponeurosis. We propose that the human foot is akin to an active suspension system for the human body, with mechanical and energetic properties that can be actively controlled by the central nervous system. NEW & NOTEWORTHY The human foot is renowned for its ability to recycle mechanical energy during locomotion, contributing up to 17% of the energy required to power a stride. This mechanism has long been considered passive in nature, facilitated by the elastic ligaments within the arch of the foot. In this paper, we present the first direct evidence that the intrinsic foot muscles also contribute to elastic energy storage and return within the human foot. Isometric contraction of the flexor digitorum brevis muscle tissue facilitates tendon stretch and recoil during controlled loading of the foot. The significance of these muscles has been greatly debated by evolutionary biologists seeking to understand the origins of upright posture and gait, as well as applied and clinical scientists. The data we present here show a potential function for these muscles in contributing to the energetic function of the human foot.

Effect of dynamic guidance-tubing short foot gait exercise on muscle activity and navicular movement in people with flexible flatfeet

2020 ◽  
Vol 47 (2) ◽  
pp. 217-226
Author(s):  
Dohee Jung ◽  
Chunghwi Yi ◽  
Woochol Joseph Choi ◽  
Joshua Sung H. You
Keyword(s):  
Pressure Distribution ◽  
Muscle Activity ◽  
Activity Ratio ◽  
Weight Bearing ◽  
Tibialis Posterior ◽  
Abductor Hallucis ◽  
Foot Pressure ◽  
Flat Feet ◽  
Flexor Digitorum Brevis ◽  
Flexor Digitorum

BACKGROUND: Navicular drop is a common plantar deformity which makes the plantar medial longitudinal arch (MLA) collapse and leads to other deformities in lower extremities. Active structures are from intrinsic and extrinsic foot muscle activities such as abductor hallucis (AbdH), tibialis anterior (TA), tibialis posterior, flexor hallucis brevis, flexor digitorum brevis during dynamic situations. As AbdH plays a role as a dynamic elevator of MLA, the importance of AbdH has been emphasized and the proper recruitment of both intrinsic and extrinsic muscle is crucial for stabilization of MLA during dynamic weight bearing condition. Because the short foot (SF) exercise is difficult to perform and tends to activate the intrinsic muscles concentrically rather than a natural coordination of concentric-isometric-eccentric activation, we have developed the guidance-tubing SF gait (GFG) exercise. OBJECTIVE: We investigated the effect of GFG exercise on muscle activity, AbdH:TA activity ratio, MLA angle, and foot pressure distribution during walking compared to SF gait (SFG) exercise. METHODS: Thirty-two subjects with flexible flat feet were divided into two groups and performed SFG exercise with (GFG) and without guidance-tubing (SFG) for seven serial days. RESULTS: AbdH muscle activity significantly increased from foot flat to heel rise in the GFG group (p = 0.006). The AbdH:TA activity ratio significantly increased in both the SFG (p = 0.015) group and GFG group (p = 0.006). MLA angles significantly decreased in both the SFG group (p = 0.001) and GFG group (p = 0.000), and the decrement was significantly higher in the GFG group (p = 0.001). The foot pressure distribution did not show any statistically significant change. CONCLUSIONS: The result of this study provides a clinical implication for training MLA supporter muscles in individuals with flat feet. The overactive muscle must be inhibited first, then facilitation and strengthening are followed respectively.

Quantifying the Contributions of the Flexor Digitorum Brevis Muscle on Postural Stability

Motor Control ◽  
2015 ◽  
Vol 19 (3) ◽  
pp. 161-172 ◽  
Author(s):  
Liria Akie Okai ◽  
André Fabio Kohn
Keyword(s):  
Postural Control ◽  
Postural Stability ◽  
Center Of Pressure ◽  
Human Foot ◽  
Sustained Activity ◽  
Torque Generation ◽  
Flexor Digitorum Brevis ◽  
The Subject ◽  
Flexor Digitorum ◽  
Intrinsic Muscles

Surprisingly little attention has been devoted to the role played by the intrinsic muscles of the human foot. The aim of this study was to quantify the capabilities of the flexor digitorum brevis (FDB) muscle to contribute to upright postural control. The approaches consisted of analysis of the effects of FDB contraction elicited by external electrical stimulation and quantification of the magnitude of FDB torque generation. The results showed the FDB can produce significant changes in static posture by itself as shown by changes in the center of pressure. Moreover, the FDB contribution to counterbalance the gravity’s toppling force was estimated at around 14.5% of the total required active torque at the ankle to keep the subject from falling. A posteriori functional analysis during horizontal perturbations showed high and self-sustained activity of FDB. These results demonstrated that the FDB has a significant capability of contributing to postural control.

scholarly journals Quantitative Ultrasound Imaging Pixel Analysis of the Intrinsic Plantar Muscle Tissue between Hemiparesis and Contralateral Feet in Post-Stroke Patients

2018 ◽  
Vol 15 (11) ◽  
pp. 2519 ◽  
Author(s):  
Cesar Calvo-Lobo ◽  
Ana Useros-Olmo ◽  
Jaime Almazán-Polo ◽  
Miriam Martín-Sevilla ◽  
Carlos Romero-Morales ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
Muscle Tissue ◽  
Quantitative Ultrasound ◽  
Total Sample ◽  
Abductor Hallucis ◽  
Cross Sectional ◽  
Significant Difference ◽  
Flexor Digitorum Brevis ◽  
Flexor Digitorum ◽  
Potential Biomarkers

Quantitative ultrasound imaging of the muscle tissue may be applied in the neurology field, due to B-mode grayscale pixels values could be used as potential biomarkers for disease progression and intervention effects in poststroke patients. Thus, the study aim was to compare and analyze the ultrasound imaging B-mode pixels differences between the intrinsic plantar muscles cross-sectional area (CSA) in hemiparetic and contralateral feet from poststroke patients by means of the Image J software. A case-control design and a convenience sampling method were used in order to recruit 22 feet from 11 poststroke patients. This total sample was divided into 11 hemiparetic feet and 11 contralateral feet. The Image J software was used in order to evaluate the interface distance, CSA as well as measure the pixels mean, standard deviation (SD) and count from all offline images in the flexor digitorum brevis, abductor hallucis (AbH), and flexor hallucis brevis muscles. Statistically significant differences (p = 0.003) were only shown for the pixels count in the AbH muscle. The rest of outcome measurements did not show any statistically significant difference (p > 0.05). Therefore, B-mode ultrasound imaging Image J software differences for the pixels count reduction were shown in the AbH muscle between hemiparetic and contralateral feet from poststroke patients. Further studies are necessary in order to apply our findings as potential biomarkers during the stroke disease course.

Ultrasound Measures of Intrinsic Foot Muscle Size and Activation Following Lateral Ankle Sprain and Chronic Ankle Instability

2021 ◽  
pp. 1-11
Author(s):  
John J. Fraser ◽  
Rachel Koldenhoven ◽  
Jay Hertel
Keyword(s):  
Ankle Sprain ◽  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
Muscle Size ◽  
Abductor Hallucis ◽  
Cross Sectional ◽  
Lateral Ankle Sprain ◽  
Lateral Ankle ◽  
Flexor Digitorum Brevis ◽  
Flexor Digitorum

Context: Tibial nerve impairment and reduced plantarflexion, hallux flexion, and lesser toe flexion strength have been observed in individuals with recent lateral ankle sprain (LAS) and chronic ankle instability (CAI). Diminished plantar intrinsic foot muscles (IFMs) size and contraction are a likely consequence. Objectives: To assess the effects of ankle injury on IFM size at rest and during contraction in young adults with and without LAS and CAI. Setting: Laboratory. Design: Cross-sectional. Patients: A total of 22 healthy (13 females; age = 19.6 [0.9], body mass index [BMI] = 22.5 [3.2]), 17 LAS (9 females; age =21.8 [4.1], BMI = 24.1 [3.7]), 21 Copers (13 females; age = 20.8 [2.9], BMI = 23.7 [2.9]), and 20 CAI (15 females; age = 20.9 [4.7], BMI = 25.1 [4.5]). Main Outcome Measures: Foot Posture Index (FPI), Foot Mobility Magnitude (FMM), and ultrasonographic cross-sectional area of the abductor hallucis, flexor digitorum brevis, quadratus plantae, and flexor hallucis brevis were assessed at rest, and during nonresisted and resisted contraction. Results: Multiple linear regression analyses assessing group, sex, BMI, FPI, and FMM on resting and contracted IFM size found sex (B = 0.45; P < .001), BMI (B = 0.05; P = .01), FPI (B = 0.07; P = .05), and FMM × FPI interaction (B = −0.04; P = .008) accounted for 19% of the variance (P = .002) in resting abductor hallucis measures. Sex (B = 0.42, P < .001) and BMI (B = 0.03, P = .02) explained 24% of resting flexor digitorum brevis measures (P < .001). Having a recent LAS (B = 0.06, P = .03) and FMM (B = 0.04, P = .02) predicted 11% of nonresisted quadratus plantae contraction measures (P = .04), with sex (P < .001) explaining 13% of resting quadratus plantae measures (B = 0.24, P = .02). Both sex (B = 0.35, P = .01) and FMM (B = 0.15, P = .03) predicted 16% of resting flexor hallucis brevis measures (P = .01). There were no other statistically significant findings. Conclusions: IFM resting ultrasound measures were primarily determined by sex, BMI, and foot phenotype and not injury status. Routine ultrasound imaging of the IFM following LAS and CAI cannot be recommended at this time but may be considered if neuromotor impairment is suspected.

Sign in / Sign up

Export Citation Format

Share Document