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 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.

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 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.

scholarly journals Morphological and mechanical properties of plantar fascia and intrinsic foot muscles in individuals with and without flat foot

2018 ◽  
Vol 26 (3) ◽  
pp. 230949901880248 ◽  
Author(s):  
Serkan Taş ◽  
Nezehat Özgül Ünlüer ◽  
Feza Korkusuz
Keyword(s):  
Mechanical Properties ◽  
Morphological Characteristics ◽  
Plantar Fascia ◽  
Abductor Hallucis ◽  
Flat Foot ◽  
Foot Posture ◽  
Intrinsic Foot Muscles ◽  
Flexor Digitorum Brevis ◽  
Flexor Digitorum ◽  
Intrinsic Muscles

Purpose: Many musculoskeletal disorders are associated with over-pronated foot and decreased medial longitudinal arch (MLA) height. Foot intrinsic muscles and plantar fascia (PF) are the primary structures that support MLA. An important reason for the over-pronated foot and the reduction in the MLA height may be the morphological characteristics of the foot intrinsic muscles and PF as well as changes in their mechanical properties. The aim of the present study is to investigate the morphologic structure and mechanical properties of PF, flexor hallucis brevis (FHB), flexor digitorum brevis (FDB), and abductor hallucis (AbH) muscles in individuals with flat foot and to compare the results with those of healthy individuals. Methods: The study included 80 participants, 40 with flat foot and 40 with normal foot posture. The foot posture of the participants was assessed using the Foot Posture Index. PF, FHB, FDB, and AbH thickness and stiffness were measured with an ultrasonography device using a linear ultrasonography probe. Results: Individuals with flat foot had higher AbH thickness compared to individuals with normal foot posture ( p < 0.001), whereas both groups were similar in terms of PF ( p = 0.188), FHB ( p = 0.627), and FDB ( p = 0.212) thickness. Stiffness values of the assessed tissues were similar in both groups ( p > 0.05). Conclusion: AbH thickness was higher in individuals with flat foot; however, PF, FHB, and FDB thickness were similar in both groups. In addition, our results suggest that foot posture is not related to the stiffness of the assessed tissues.

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.

scholarly journals Intrinsic foot muscles have the capacity to control deformation of the longitudinal arch

2014 ◽  
Vol 11 (93) ◽  
pp. 20131188 ◽  
Author(s):  
Luke A. Kelly ◽  
Andrew G. Cresswell ◽  
Sebastien Racinais ◽  
Rodney Whiteley ◽  
Glen Lichtwark
Keyword(s):  
Electrical Stimulation ◽  
External Load ◽  
Energy Savings ◽  
Maximum Load ◽  
Metabolic Energy ◽  
Abductor Hallucis ◽  
Muscle Stretch ◽  
Human Foot ◽  
Longitudinal Arch ◽  
Intrinsic Foot Muscles

The human foot is characterized by a pronounced longitudinal arch (LA) that compresses and recoils in response to external load during locomotion, allowing for storage and return of elastic energy within the passive structures of the arch and contributing to metabolic energy savings. Here, we examine the potential for active muscular contribution to the biomechanics of arch deformation and recoil. We test the hypotheses that activation of the three largest plantar intrinsic foot muscles, abductor hallucis, flexor digitorum and quadratus plantae is associated with muscle stretch in response to external load on the foot and that activation of these muscles (via electrical stimulation) will generate sufficient force to counter the deformation of LA caused by the external load. We found that recruitment of the intrinsic foot muscles increased with increasing load, beyond specific load thresholds. Interestingly, LA deformation and muscle stretch plateaued towards the maximum load of 150% body weight, when muscle activity was greatest. Electrical stimulation of the plantar intrinsic muscles countered the deformation that occurred owing to the application of external load by reducing the length and increasing the height of the LA. These findings demonstrate that these muscles have the capacity to control foot posture and LA stiffness and may provide a buttressing effect during foot loading. This active arch stiffening mechanism may have important implications for how forces are transmitted during locomotion and postural activities as well as consequences for metabolic energy saving.

scholarly journals Active regulation of longitudinal arch compression and recoil during walking and running

2015 ◽  
Vol 12 (102) ◽  
pp. 20141076 ◽  
Author(s):  
Luke A. Kelly ◽  
Glen Lichtwark ◽  
Andrew G. Cresswell
Keyword(s):  
Stance Phase ◽  
Phase Changes ◽  
Gait Velocity ◽  
Force Transmission ◽  
Abductor Hallucis ◽  
Plantar Aponeurosis ◽  
Human Foot ◽  
Longitudinal Arch ◽  
Intrinsic Foot Muscles

The longitudinal arch (LA) of the human foot compresses and recoils in response to being cyclically loaded. This has typically been considered a passive process, however, it has recently been shown that the plantar intrinsic foot muscles have the capacity to actively assist in controlling LA motion. Here we tested the hypothesis that intrinsic foot muscles, abductor hallucis (AH), flexor digitorum brevis (FDB) and quadratus plantae (QP), actively lengthen and shorten during the stance phase of gait in response to loading of the foot. Nine participants walked at 1.25 m s −1 and ran at 2.78 and 3.89 m s −1 on a force-instrumented treadmill while foot and ankle kinematics were recorded according to a multisegment foot model. Muscle–tendon unit (MTU) lengths, determined from the foot kinematics, and intramuscular electromyography (EMG) signals were recorded from AH, FDB and QP. Peak EMG amplitude was determined during the stance phase for each participant at each gait velocity. All muscles underwent a process of slow active lengthening during LA compression, followed by a rapid shortening as the arch recoiled during the propulsive phase. Changes in MTU length and peak EMG increased significantly with increasing gait velocity for all muscles. This is the first in vivo evidence that the plantar intrinsic foot muscles function in parallel to the plantar aponeurosis, actively regulating the stiffness of the foot in response to the magnitude of forces encountered during locomotion. These muscles may therefore contribute to power absorption and generation at the foot, limit strain on the plantar aponeurosis and facilitate efficient foot ground force transmission.

scholarly journals Intrinsic Foot Muscle Activation During Specific Exercises: A T2 Time Magnetic Resonance Imaging Study

2016 ◽  
Vol 51 (8) ◽  
pp. 644-650 ◽  
Author(s):  
Thomas M. Gooding ◽  
Mark A. Feger ◽  
Joseph M. Hart ◽  
Jay Hertel
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Muscle Activation ◽  
Imaging Study ◽  
Percentage Increase ◽  
Resonance Imaging ◽  
Abductor Hallucis ◽  
Intrinsic Foot Muscles ◽  
Intrinsic Foot Muscle ◽  
T2 Mri

Context: The intrinsic foot muscles maintain the medial longitudinal arch and aid in force distribution and postural control during gait. Impaired intrinsic foot-muscle function has been linked to various foot conditions. Several rehabilitative exercises have been proposed to improve it; however, literature that identifies which individual muscles are activated during specific intrinsic foot-muscle exercises is lacking. Objective: To describe changes in activation of the intrinsic plantar foot muscles after 4 exercises as measured with T2 magnetic resonance imaging (MRI). Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: Eight healthy National Collegiate Athletic Association Division I collegiate cross-country and track athletes (5 men and 3 women: age = 20 ± 0.93 years, height = 180.98 ± 10.84 cm, mass = 70.91 ± 7.82 kg). Intervention(s): Participants underwent T2 MRI before and after each exercise. They completed 1 set of 40 repetitions of each exercise (short-foot exercise, toes spread out, first-toe extension, second- to fifth-toes extension). Main Outcome Measure(s): Percentage increases in muscle activation of the abductor hallucis, flexor digitorum brevis, abductor digiti minimi, quadratus plantae, flexor digiti minimi, adductor hallucis oblique, flexor hallucis brevis, and interossei and lumbricals (analyzed together) after each exercise were assessed using T2 MRI. Results: All muscles showed increased activation after all exercises. The mean percentage increase in activation ranged from 16.7% to 34.9% for the short-foot exercise, 17.3% to 35.2% for toes spread out, 13.1% to 18.1% for first-toe extension, and 8.9% to 22.5% for second- to fifth-toes extension. All increases in activation had associated 95% confidence intervals that did not cross zero. Conclusions: Each of the 4 exercises was associated with increased activation in all of the plantar intrinsic foot muscles evaluated. These results may have clinical implications for the prescription of specific exercises to target individual intrinsic foot muscles.

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.

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