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only saw the abstract but looked interesting
Brain Res. 2005 Nov 16;1062(1-2):48-62. Epub 2005 Oct 24.
The authors maintained their study "(supported) the hypothesis that cutaneous reflexes from the foot contribute to the maintenance of stability during walking."
Plantar cutaneous input modulates differently spinal reflexes in subjects with intact and injured spinal cord. Spinal Cord. 2006 Mar 14;
Quote:
Study design:Spinal reflex excitability study in sensory-motor incomplete spinal cord-injured (SCI) and spinal intact subjects.Objectives:To investigate the effects of plantar cutaneous afferent excitation on the soleus H-reflex and flexion reflex in both subject groups while seated.
Setting:Rehabilitation Institute of Chicago and City University of New York, USA.
Methods:The flexion reflex in SCI subjects was elicited by non-nociceptive stimulation of the sural nerve. In normal subjects, it was also elicited via innocuous medial arch foot stimulation. In both cases, reflex responses were recorded from the ipsilateral tibialis anterior muscle. Soleus H-reflexes were elicited and recorded via conventional methods. Both reflexes were conditioned by plantar cutaneous afferent stimulation at conditioning test intervals ranging from 3 to 90 ms.
Results:Excitation of plantar cutaneous afferents resulted in facilitation of the soleus H-reflex and late flexion reflex in SCI subjects. In normal subjects, the soleus H-reflex was depressed while the late flexion reflex was absent. The early flexion reflex was irregularly observed in SCI patients, while in normal subjects a bimodal reflex modulation pattern was observed.
Conclusion:The effects of plantar cutaneous afferents change following a lesion to the spinal cord leading to exaggerated activity in both flexors and extensors. This suggests impaired modulation of the spinal inhibitory mechanisms involved in the reflex modulation. Our findings should be considered in programs aimed to restore sensorimotor function and promote recovery in these patients.Sponsorship:NIH, NICHD, Grant no. 1R03HD043951-01 and PSC CUNY Research Award no. 67051-0036.Spinal Cord advance online publication, 14 March 2006; doi:10.1038/sj.sc.3101917.
Immediate effects of plantar inputs on the upper half muscles and upright posture: a preliminary study. Cranio. 2006 Jan;24(1):50-9.
Quote:
This purpose of this study was to investigate the immediate effects of plantar inputs on both the upper half muscle activity (anterior temporal, masseter, digastric, sternocleidomastoid, upper and lower trapezius, cervical) and the body posture, by means of electromyography (EMG) and vertical force platform, respectively. Twenty four (24) healthy adults, between the ages of 24 and 31 years (25.3 +/- 1.9), with no history of craniomandibular disorder or systemic musculoskeletal dysfunction, were randomly divided into two groups: test group (fourteen subjects) and control group (ten subjects). A first recording session (TO) measured the baseline EMG and postural patterns of both groups. After this session, the test group wore test shoes with insoles that stimulated the plantar surfaces, while the control group wore placebo shoes. After one hour, a second set of measurements (T1) were performed. Significant differences between the groups at baseline were observed in the left anterior temporal, left cervical, and left upper trapezius, as well as at T1 in the left anterior temporal and right upper trapezius (p < 0.05). Within-test group analysis showed a significant increase of the right upper trapezius activity (p < 0.05), whereas no changes were found by within-control group analysis. Lower risk of asymmetric muscle patterns and postural blindness in the test group compared to the control group was observed. Further studies are warranted to investigate the short and long-term effects of this type of insole, in patients with both craniomandibular-cervical and lower extremity disorders.
There was a study releasde from Europe three months or so ago (I'm Looking for the reference) that looked for any differences to the conduction time in the nreves of the lower limb comparing runners to the average 'Joe'.
They found that the runners had delayed conduction time of 20msecs to the plantar nerves compared to the averag 'joe' who did not run.
So who is right?
Bet this mob were. I will post it when I find the paper. I know it was re-published in the Autralian Sports Medicine Journal of ?April 2006.
I found the whole article and the delay is 20 msecs. I presume this delay indicates that most important information comes from the joints not the skin as the late Janda used to advocate.
Location specificity of plantar cutaneous reflexes involving lower limb muscles in humans. Exp Brain Res. 2006 Jul 18;
Quote:
It is known that cutaneous reflexes in human hand muscles show strong location-specificity dependent on the digit stimulated. We hypothesized that in lower leg muscles the cutaneous reflex following tactile sensation of the plantar surface of the foot is also organized in a location-specific manner. The purpose of the present study was to test this hypothesis. Middle latency reflexes ( approximately 70-110 ms, MLR) following non-noxious electrical stimulation to different locations on the plantar foot were recorded from 16 neurologically intact volunteers (15 males, 1 female). Electrical stimulation was given to the fore-medial (f-M), fore-lateral (f-L) and heel (HL) regions of the plantar surface of the right foot while the subjects performed isometric dorsiflexion (tibialis anterior, TA), plantarflexion (soleus, Sol and medial gastrocnemius, MG), eversion (peroneus longus, PL) and knee extension (vastus lateralis, VL) while sitting and standing. In the Sol and MG, an excitatory response was observed following HL stimulation, which was switched to an inhibitory response following f-M or f-L stimulation (P < 0.001). A reciprocal pattern in contrast to Sol was observed in the TA. In the PL, MLR exhibited significant excitation following both f-L and HL stimulation, which, however, was switched to an inhibitory response following f-M stimulation (P < 0.001). Moderate inhibition of the MLR was seen in the VL for all stimulated positions. Systematic stimulation along the lateral side of the plantar foot demonstrated that the reflex reversal occurred around the middle of the plantar foot in the Sol and TA. In all muscles tested, the slope of the regression line between the magnitude of the MLR and background electromyographic activity significantly decreased during standing compared with sitting except for the PL following f-L simulation. These results suggest that reflex effects from cutaneous nerves in the plantar foot onto the motoneurons innervating the lower leg muscles are organized in a highly topographic manner in humans. The organization of these reflexes may play an important role in the alteration of limb loading and/or ground contact in response to tactile sensation of the plantar foot while sitting and standing.
Contact force- and amplitude-controllable vibrating probe for somatosensory mapping of plantar afferences with fMRI. J Magn Reson Imaging. 2006 Oct 9;
Gallasch E, Golaszewski SM, Fend M, Siedentopf CM, Koppelstaetter F, Eisner W, Gerstenbrand F, Felber SR
Quote:
PURPOSE: To study cerebral responses evoked from mechanoreceptors in the human foot sole using a computer-controlled vibrotactile stimulation system.
MATERIALS AND METHODS: The stimulation system consisted of two stationary moving magnet actuators with indentors to gently contact and vibrate the foot sole during functional MRI (fMRI) experiments. To allow independent settings of contact force (0-20 N) and intensity of vibration (frequency range = 20-100 Hz) the actuators were controlled by a digital servo loop. For fMRI experiments with complex stimulus protocols, both vibrating probes were further operated under supervisory control.
RESULTS: The MR compatibility of this electromagnetic system was tested in a 1.5T scanner with an actively shielded magnet (Siemens Magnetom Sonata). Blood oxygenation level-dependent (BOLD) responses were detected in the contralateral left pre- and postcentral gyrus, bilaterally within the secondary somatosensory cortex, bilaterally within the supplementary motor cortex, and bilaterally within the anterior cingular gyrus.
CONCLUSION: This stimulation device provides a new tool for identifying cerebral structures that convey sensory information from the foot region, which is of promising diagnostic value, particularly for assessing sensorimotor deficits resulting from brain lesions.
Re: Cutaneous reflexes contribute to stability during walking
Relative contribution of the pressure variations under the feet and body weight distribution over both legs in the control of upright stance. J Biomech. 2006 Dec 27;
Rougier PR
Quote:
The resultant centre of pressure (CP(Res)) trajectories are aimed at controlling body movements in upright stance. When standing on two legs, these trajectories are generated by exerting reaction forces under each foot and by loading-unloading mechanisms intervening at the hip level. To assess the respective contribution of each of these factors in stance maintenance, a group of healthy individuals were tested in several conditions including standing quietly and voluntarily producing under each foot larger CP displacements in phase and in opposite phase along medio-lateral (ML) and antero-posterior (AP) axes. The results, based on the computation of coefficients of correlation between CP(Res) trajectories and various time series including the relative body weight applied to one leg and plantar CP trajectories, highlight some differences according to the axes along which the displacements take place and the amplitudes of the movements. Furthermore, the comparison of the CP(Res) trajectories resulting from each one of these two factors reveals the predominant role played by the loading-unloading mechanisms intervening at the hip level for the movements along the ML axis and those of the plantar CP displacements along the AP axis. Increasing the plantar CP displacements in phase or in opposite phase substantially modifies these contributions although without inferring a shift to the benefit of the other mechanism. The specific morphology of the ankle and hip joints implicated in this postural task plainly explains this postural control organisation. In particular, the link between the segmental configuration of the lower limbs and these mechanisms are discussed.
Re: Cutaneous reflexes contribute to stability during walking
Facilitation of the soleus stretch reflex induced by electrical excitation of plantar cutaneous afferents located around the heel. Neurosci Lett. 2007 Jan 21;
Sayenko DG, Vette AH, Kamibayashi K, Nakajima T, Akai M, Nakazawa K
Quote:
Previous studies have demonstrated that plantar cutaneous afferents can adjust motoneuronal excitability, which may contribute significantly to the control of human posture and locomotion. However, the role of plantar cutaneous afferents with respect to their location specificity in modulating the mechanically induced stretch reflex still remains unclear. In the present study, it was hypothesized that electrical stimulation of the ipsilateral heel region of the foot is followed by a modulation of spinal excitability, leading to a facilitation of the soleus motor output. The study was performed to investigate the effect of excitation of plantar cutaneous afferents located around the heel on the soleus stretch reflex. The soleus stretch reflex was evoked by rotating the ankle joint in dorsiflexion direction at two different angular velocities of 50 and 200 degrees s(-1). A conditioning pulse train of non-noxious electrical stimulation was delivered to the plantar surface of the heel at different conditioning test intervals ranging from 5 to 100ms. Excitation of plantar cutaneous afferents around the heel resulted in a pronounced facilitation of the soleus stretch reflex with magnitude and time course comparable for both velocities. This facilitation was manifested by a significant increase of reflex size for conditioning test intervals from 30 to 70ms. The observed effect implies a potential functional role of cutaneous afferents in balance control conditions where the ankle is naturally disturbed, e.g., during step reactions to external perturbations.
Re: Cutaneous reflexes contribute to stability during walking
Dear All
Nothing new. In Travell and Simon's book volume 2 the lower limb, shows the myotomal referral pattern from the soleus muscle to involve the area around the heel.
The notion of proactive control of landings is generally accepted, and some underlying mechanisms have already been described. Only little is known on adjustments at the foot level, however. The authors therefore investigated the foot and ankle behavior of 24 participants as they landed on differently inclined surfaces. A 4-segment model of the foot and ankle provided 3-dimensional kinematics. They also analyzed activation patterns from several muscles and the ground reaction force. Participants anticipated the different surfaces, as shown by the forefoot kinematics and the activation patterns before touch down. Anticipation of the surface inclination led to adjustments in forefoot orientation and probably also in joint stiffness. The authors suggest that those adjustments tend to enhance the self-stabilizing potential of the mechanical system. The enhancement of that potential would ease the subsequent stabilization, reducing the demands on the neural system.
The purpose of this study was to assess the effect of diminished plantar cutaneous sensation induced by cooling on postural control during double- and single-limb quiet standing. 32 healthy adults were tested on an intervention day and control day. The intervention consisted of 10 min. of ice immersion of the plantar aspect of the feet prior to balance testing. Dependent variables were center of pressure velocity and area during double- and single-limb stance with eyes open and closed. Significant interactions were found between sensation and vision for double-limb center of pressure area, with a significant reduction in area of center of pressure excursions after reducing sensation with eyes closed but not with eyes open. The area of center of pressure excursions may have been reduced in an effort to curtail exploratory postural behavior given the altered afferent input from plantar receptors. There were no significant differences for plantar hypoesthesia in single-limb stance.
I find this type of paper just a big I knew the answer.
Two things give the outcome answers.
Remember many people climb mount everest and other peaks....
We only measure pressure and temperature, so in bipedal stance with freezing feet one would expect the foot to try and reduce the area in contact with the ground so as to preserve heat/energy loss, while in single stance there is no option but to place ones foot on the ground if you wish not to fall over.
Basically a known outcome.
They would be better off keeping their beer cool.........
Paul Conneely www.musmed.com.au
have a look to see how mobilisation changes feet/ankle angles and other unique bits
Background
Impaired plantar cutaneous sensation is often seen clinically and can lead to postural instability. It is not clear if the severity of such sensory loss would be associated with postural stability, and if such an association would be affected by sensory redundancy and task difficulty. The purpose of this study was to investigate the association of the degree of somatosensory loss and postural stability by experimentally induced somatosensory loss in healthy young adults.
Methods
Twenty-one healthy young adults performed four quiet standing tasks (normal or narrow base, and eyes open or closed) on a force platform under three somatosensory conditions induced by ischemic blocking of afferent conduction below the ankle, normal, partial loss and complete loss. Differences in the standing center of pressure motion between the three sensory loss conditions were compared.
Findings
There was a significant trend of greater center of pressure motion with increasing severity of sensory loss in all task conditions. The differences in the center of pressure motion between partial and total loss conditions were significant only in conditions where vision was removed and the support surface was narrow.
Interpretation
Increased severity of experimentally induced loss of plantar cutaneous sensitivity was associated with greater postural sway. Such an association was affected by the availability of visual input and the size of the support surface. Clinically for patients with somatosensory impairments of the foot, postural stability should be given special attention.
Re: Cutaneous reflexes contribute to stability during walking
Dear All
Interesting but I do not hear of people who have severe diabetes of peripheral nerve neuropathy due to unknown causes ever complain about swaying gait nor does one see it.
One outcome is acute, that is the experiment while the other is chronic and allows for time adaption.
Re: Cutaneous reflexes contribute to stability during walking
Quote:
Originally Posted by musmed
Dear All
Interesting but I do not hear of people who have severe diabetes of peripheral nerve neuropathy due to unknown causes ever complain about swaying gait nor does one see it.
One outcome is acute, that is the experiment while the other is chronic and allows for time adaption.
Cute but ? practical
Musmed
Paul:
Individuals with peripheral neuropathy, where the sensory function of the feet are severely compromised, do show gait changes. They don't necessarily exhibit a "swaying gait. However, they will take smaller steps, use a wider base of gait and show more foot abduction during gait in order to give themselves more stability. These gait compensations allow the individual to put their center of mass further medial to the center of pressure of their stance phase foot than normal which will decrease their likelihood of falling laterally. This is a common gait finding in these individuals.
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Re: Cutaneous reflexes contribute to stability during walking
Quote:
Originally Posted by Kevin Kirby
Paul:
Individuals with peripheral neuropathy, where the sensory function of the feet are severely compromised, do show gait changes. They don't necessarily exhibit a "swaying gait. However, they will take smaller steps, use a wider base of gait and show more foot abduction during gait in order to give themselves more stability. These gait compensations allow the individual to put their center of mass further medial to the center of pressure of their stance phase foot than normal which will decrease their likelihood of falling laterally. This is a common gait finding in these individuals.
Great chapter on peripheral neuropathies in: GAIT DISORDERS OF AGING. FALLS AND THERAPEUTIC STRATEGIES. Edited by Joseph C. Masdeu, Lewis Sudarsky, and Leslie Wolfson. Philadelphia, Lippincott-Raven, 1997
Among other things, they discuss why these patients are more likely to fall backwards!
Re: Cutaneous reflexes contribute to stability during walking
Quote:
Originally Posted by Kevin Kirby
Paul:
Individuals with peripheral neuropathy, where the sensory function of the feet are severely compromised, do show gait changes. They don't necessarily exhibit a "swaying gait. However, they will take smaller steps, use a wider base of gait and show more foot abduction during gait in order to give themselves more stability. These gait compensations allow the individual to put their center of mass further medial to the center of pressure of their stance phase foot than normal which will decrease their likelihood of falling laterally. This is a common gait finding in these individuals.
Dear Kevin
I agree that people do have a wider gait etc. but never have I had a swaying patient present to me with the statement, "look at my gait, what is wrong with me" outside of cerebral ischaemia/stroke etc.
Interesting that Chronic (years and years) long distance runners who have a 50 millisecond delay in plantar nerve transmission do not exhibit this gait.
I presume there aer many other factors involved that we do not understand just yet.....
Re: Cutaneous reflexes contribute to stability during walking
Quote:
Originally Posted by musmed
Dear Kevin
I agree that people do have a wider gait etc. but never have I had a swaying patient present to me with the statement, "look at my gait, what is wrong with me" outside of cerebral ischaemia/stroke etc.
Paul:
The reason that people with peripheral neuropathy don't "sway" is likely because they have learned to walk with shorter strides, with a wider base of gait and with an abducted gait. In addition, the sensory signals for balance that the central nervous system (CNS) processes are not just limited to the cutaneous receptors of the plantar feet. The signals for balance come from the inner ear, eyes, joint and tendon receptors and, if I remember correctly, are also processed through the cerebellum. As a result, even in those individuals with no cutaneous receptors in their feet, such as in bilateral amputees, there is enough sensory input to the CNS from the other afferents that affect balance that these individuals can easily walk without a "sway" (and even walk with a push from the prostheses during the terminal stance phase of gait!).
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Re: Cutaneous reflexes contribute to stability during walking
Quote:
Originally Posted by Kevin Kirby
Paul:
The reason that people with peripheral neuropathy don't "sway" is likely because they have learned to walk with shorter strides, with a wider base of gait and with an abducted gait. In addition, the sensory signals for balance that the central nervous system (CNS) processes are not just limited to the cutaneous receptors of the plantar feet. The signals for balance come from the inner ear, eyes, joint and tendon receptors and, if I remember correctly, are also processed through the cerebellum. As a result, even in those individuals with no cutaneous receptors in their feet, such as in bilateral amputees, there is enough sensory input to the CNS from the other afferents that affect balance that these individuals can easily walk without a "sway" (and even walk with a push from the prostheses during the terminal stance phase of gait!).
Kevin
Exactly, but if you reread the study abnormal gait is the be all and end all. That is why I think the study has no practical benefit.Amen
Our purpose was to identify the effect of diminished plantar cutaneous sensation on time-to-boundary (TTB) measures of postural control during double and single limb quiet standing. Thirty-two healthy young adults underwent 10 min of ice immersion of the plantar aspect of the feet prior to balance testing. On a different day, the subjects did not receive this intervention prior to testing. A 2 x 2 vision (eyes open, eyes closed) by sensation (control, hypoesthesia) repeated measures design was used to analyze the TTB measures. In double limb stance, there were significant interactions between sensation and vision for the absolute TTB minimum and the mean of TTB minima in the anteroposterior (AP) direction. There was a significant increase in both measures after sensation was diminished with eyes closed compared to the control, but not with eyes open. In single limb stance, the TTB absolute minimum, the mean of TTB minima in the AP direction, and the standard deviation of TTB minima significantly increased with hypoesthesia regardless of vision. No significant differences were found in the medial-lateral (ML) direction for any of the TTB measures in double or single limb stance. Sensory information from the plantar cutaneous receptors appears to be most important in the maintenance of AP postural control.
Reduced plantar sensation secondary to chronic diffuse polyneuropathy (PN) is believed to reduce locomotor stability, especially when walking at non-preferred speeds. However, the contribution of plantar sensation to the maintenance of locomotor stability is not entirely clear. The purpose of this study was to examine the effects of acute loss of plantar sensation on the stability-related kinematic properties of walking at different speeds. Lower-extremity joint kinematics were acquired as healthy young adults walked on a treadmill at their preferred walking speed (PWS) and three predetermined speeds (0.8, 1.0, and 1.2m/s) under both normal and desensitized conditions. Desensitization of the foot soles was induced by ice-exposure, and plantar pressure sensation was assessed by a 5.07 monofilament. The average magnitude of stride duration variability (SDvar) and lower-extremity joint angle variability (JTvar), as well as short- and long-term "finite-time" Lyapunov exponents (lambda(ST)( *), lambda(LT)( *)) associated with lower-extremity joint angles were computed. Ice-induced plantar desensitization led to increased lambda(ST)( *) ( approximately 40%) and lambda(LT)( *) ( approximately 8%) values but did not affect SDvar or JTvar. Higher treadmill speed led to greater lambda(ST)( *) and lambda(LT)( *) values, but the speed effects were not influenced by plantar desensitization.While acute loss of plantar sensation does not appear to influence the magnitude of spatial or temporal variability, it did attenuate the state-space trajectory divergence caused by stride-to-stride variability (i.e., lambda(ST)( *) and lambda(LT)( *)). However, as opposed to walking at PWS, otherwise healthy locomotor systems do not appear to place increased reliance on plantar sensation when walking at non-preferred treadmill speeds.
The aim was to determine the contributions of foot mechanoreceptive sensation, vision and their interaction on postural stability during quiet stance, balance perturbations and adaptive adjustments. Postural stability was measured as anteroposterior torque variance in Young (n = 25, average age = 25.1 years) and Elderly subjects (n = 16, average age = 71.5 years) during repeated calf vibrations while standing with eyes open and closed. Sensation, recorded using vibration perception and tactile sensitivity, was poorer in elderly than young subjects. Sensation was of low importance for stability during quiet stance and the first 50 s of repeated vibrations, but was associated with stability during the last three 50 s periods of balance perturbations, suggesting that the mechanoreceptive sensation affected how well postural control could adapt to repeated balance perturbations. The findings suggest that clinicians should investigate whether patients with balance problems and poor adaptation have mechanoreceptive sensation deficits
Re: Cutaneous reflexes contribute to stability during walking
Association of lower limb cutaneous sensitivity with gait speed in the elderly: the health ABC study.
Deshpande N, Ferrucci L, Metter J, Faulkner KA, Strotmeyer E, Satterfield S, Schwartz A, Simonsick E. Am J Phys Med Rehabil. 2008 Nov;87(11):921-8
Quote:
OBJECTIVE: To examine the association of fast-adapting receptor-mediated vibrotactile sensitivity and slow-adapting receptor-mediated pressure sensitivity with self-selected usual gait speed and gait speed over a challenging narrow (20 cm wide) course.
DESIGN: Participants from the population-based older cohort of the Health ABC study were included (n = 1721; age: 76.4 +/- 2.8 yrs). Usual gait speed over 6 m and gait speed over a 6-m narrow course were measured. Vibration perception threshold (100 Hz) was measured on the plantar surface, and monofilament testing (1.4 and 10 g) was performed on the dorsum of the great toe. Covariates including knee extensor torque, standing balance, visual acuity and contrast sensitivity, knee pain, depressive symptoms, high fasting glucose levels, and peripheral arterial disease were evaluated.
RESULTS: Vibrotactile and monofilament sensitivity were significantly worse in slower gait speed groups in both walking conditions (P < 0.001 to P = 0.015). Adjusting for covariates, vibrotactile (P < 0.001) but not monofilament sensitivity (P = 0.655) was independently associated with self-selected normal gait speed. Neither sensory function was associated with narrow-base gait speed.
CONCLUSIONS: In the elderly, poor lower limb vibrotactile sensitivity measured on the plantar surface of the great toe, but not the pressure sensitivity as measured by monofilament testing on the dorsum of the great toe, is independently associated with slower self-selected normal gait speed. Narrow-based walking seems to depend on other neuromuscular mechanisms.
Re: Cutaneous reflexes contribute to stability during walking
The effects of unilateral medial arch support stimulation on plantar pressure and center of pressure adjustment in young gymnasts.
Janin M, Dupui P. Neurosci Lett. 2009 Jun 21. [Epub ahead of print]
Quote:
The purpose of this study was to examine the contribution of tactile afferents from the medial arch of the foot on postural control. The center of pressure (CoP) position and right/left plantar pressure distributions of 13 gymnasts, with and without a medial arch support, were recorded by a force platform coupled with a baropedometry analysis. Stimulation of the subject's plantar sole was accomplished using a 3mm thick medial arch insert. Right arch stimulation induced an ipsilateral increase of plantar pressure and a contralateral displacement of the CoP to the left. Left arch support also resulted in an ipsilateral increase in plantar pressure and displacement of the CoP to the right. Stimulation of the plantar arch may induce a perception that the body's center of mass has shifted toward the stimulated foot. To maintain stability, individuals may then shift their CoP in the opposite direction. This response may involve compensatory muscle activation strategies to adjust posture. Clinicians may apply these results in their use of foot orthoses to address postural anomalies in patients.
Re: Cutaneous reflexes contribute to stability during walking
The effect of prolonged standing on touch sensitivity threshold of the foot: a pilot study.
Wiggermann NE, Werner RA, Keyserling WM. PM R. 2012 Feb;4(2):117-22.
Quote:
OBJECTIVE:
To determine the effect of prolonged standing on touch sensitivity of the foot.
DESIGN:
An observational study with replications.
SETTING:
University laboratory.
PARTICIPANTS:
Ten healthy college students (5 men and 5 women), with a mean ± SD age of 23.5 ± 4.1 years and body mass of 67.4 ± 12.6 kg.
METHODS:
Semmes-Weinstein monofilament tests were administered to 12 locations on the dorsal and plantar surfaces of the foot before and after 4 hours of standing. These locations were formed into several groupings (toes, metatarsal heads, midfoot, heel, all plantar sites, all dorsal sites), and paired t-tests were used to test for significant changes in sensitivity threshold after standing.
MAIN OUTCOME MEASUREMENT:
The difference between sensitivity thresholds measured before and after standing for different locations on the foot.
RESULTS:
The average of all sensitivity thresholds on the plantar surface of the foot decreased (indicating increased sensitivity) from 0.56 to 0.36 g (P < .01) after 4 hours of prolonged standing. This change in threshold equated to a difference of 1 Semmes-Weinstein monofilament level. Changes in the sensitivity threshold of the dorsal aspect of the foot were not significant.
CONCLUSIONS:
Analysis of the results suggests that the plantar foot has greater sensitivity to touch after prolonged standing. These findings may be useful for identifying potential unintended bias in clinical touch sensitivity testing. Future research is necessary to understand the underlying mechanisms for this sensitivity change and to determine the onset and recovery times for sensitivity changes.
Re: Cutaneous reflexes contribute to stability during walking
Reduced plantar cutaneous sensation modifies gait dynamics, lower-limb kinematics and muscle activity during walking.
Höhne A, Ali S, Stark C, Brüggemann GP. Eur J Appl Physiol. 2012 Mar 6.
Quote:
Peripheral neuropathy is the most common long-term complication in diabetes and is involved in changes in diabetic gait and posture. The regression of nerve function leads to various deficits in the sensory and motor systems, impairing afferent and efferent pathways in the lower extremities. This study aimed to examine how reduced plantar-afferent feedback impacts the gait pattern. Cutaneous sensation in the soles of both feet was experimentally reduced by means of intradermal injections of an anaesthetic solution, without affecting foot proprioception or muscles. Ten subjects performed level walking at a controlled velocity before and after plantar anaesthesia. Muscle activity of five leg-muscles, co-contraction ratios for the knee and ankle joint, ground reaction forces (GRF), spatiotemporal characteristics, joint angles and moments of the hip, knee and ankle were analysed. The intervention significantly lowered plantar sensation, reducing it to the level of sensory neuropathy. Spatiotemporal gait characteristics remained unchanged. The ankle joint was more dorsiflexed which coincided with increased tibialis anterior and decreased gastrocnemius medialis muscle activity during foot flat to mid-stance. In addition, the knee joint was more flexed accompanied by increased biceps femoris activity and higher internal knee-extension moment. With regard to gait dynamics, a delay of the first peak of the vertical GRF was observed. Increased soleus and tibialis anterior muscle activity were found during the end of stance. Short-term loss of plantar sensation affects lower-limb kinematics and gait dynamics, particularly during the first half of stance, and contributes to modified muscle-activation patterns during locomotion.
Cutaneous reflexes contribute to stability during walking
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