1
|
Kim KM, Kim JS, Needle AR. Soleus arthrogenic muscle inhibition following acute lateral ankle sprain correlates with symptoms and ankle disability but not with postural control. JOURNAL OF SPORT AND HEALTH SCIENCE 2024; 13:559-568. [PMID: 38428732 PMCID: PMC11184308 DOI: 10.1016/j.jshs.2024.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 10/20/2023] [Accepted: 11/27/2023] [Indexed: 03/03/2024]
Abstract
BACKGROUND Acute lateral ankle sprains (ALAS) are associated with long-term impairments and instability tied to altered neural excitability. Arthrogenic muscle inhibition (AMI) has been observed in this population; however, relationships with injury-related impairments are unclear, potentially due to the resting, prone position in which AMI is typically measured. Assessing AMI during bipedal stance may provide a better understanding of this relationship. METHODS AMI was assessed in 38 young adults (19 ALAS within 72 h of injury: 10 males, 21.4 ± 2.7 years; 19 healthy controls: 10 males, 21.9 ± 2.2 years; mean ± SD) using the Hoffmann reflex (H-reflex) during bipedal stance. Electrical stimulation was administered to identify the maximal H-reflex (Hmax) and maximal motor response (Mmax) from the soleus, fibularis longus, and tibialis anterior muscles. The primary outcome measure was the Hmax/Mmax ratio. Secondary outcomes included acute symptoms (pain and swelling), postural control during bipedal stance, and self-reported function. RESULTS No significant group-by-limb interactions were observed for any muscle. However, a significant group main effect was observed in the soleus muscle (F(1,35) = 6.82, p = 0.013), indicating significantly lower Hmax/Mmax ratios following ALAS (0.38 ± 0.20) compared to healthy controls (0.53 ± 0.16). Furthermore, lower Hmax/Mmax ratios in the soleus significantly correlated with acute symptoms and self-reported function but not with postural control. CONCLUSION This study supports previous evidence of AMI in patients with ALAS, providing insight into neurophysiologic impacts of musculoskeletal injury. Our results suggest that assessing AMI in a standing position following acute injury may provide valuable insight into how AMI develops and guide potential therapeutic options to curb and offset the formation of joint instability.
Collapse
Affiliation(s)
- Kyung-Min Kim
- Department of Sport Science, Sungkyunkwan University, Suwon-si 16419, Republic of Korea
| | - Joo-Sung Kim
- Department of Health and Human Performance, Texas State University, San Marcos, TX 78666, USA
| | - Alan R Needle
- Department of Public Health & Exercise Science, Appalachian State University, Boone, NC 28608, USA; Department of Rehabilitation Science, Appalachian State University, Boone, NC 28608, USA.
| |
Collapse
|
2
|
Needle AR, Tinsley JE, Cash JJ, Koeval BK, Barton JA, Howard JS. The effects of neuromuscular electrical stimulation to the ankle pronators on neural excitability & functional status in patients with chronic ankle instability. Phys Ther Sport 2023; 60:1-8. [PMID: 36634453 DOI: 10.1016/j.ptsp.2022.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 11/30/2022] [Accepted: 12/01/2022] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Chronic ankle instability (CAI) is associated with decreased neural excitability that negatively impacts function. This study assessed a 2-week neuromuscular electrical stimulation (NMES) or transcutaneous electrical nerve stimulation (TENS) intervention over the ankle pronators on neural excitability, performance, and patient-reported function in patients with CAI. STUDY DESIGN Randomized controlled trial. PARTICIPANTS Twenty participants with CAI completed the study. MAIN OUTCOME MEASURES Participants were assessed for reflexive and corticospinal excitability to the ankle muscles, dynamic balance, side-hop test performance and patient-reported outcomes at baseline, post-intervention (2-weeks), and retention (4-weeks). Between baseline and post-intervention, participants reported for 5 sessions where they received either sub-noxious NMES (n = 11) or sensory-level TENS (n = 9) over the ankle pronators. RESULTS Improved reflexive excitability to the ankle pronators was observed in TENS at post-intervention (p = 0.030) and retention (p = 0.029). Cortical excitability to the dorsiflexors increased in TENS at post-intervention (p = 0.017), but not at retention (p = 0.511). No significant changes were found for other neural measures, balance ability, hopping, or patient-reported function (p > 0.050). CONCLUSIONS Our results suggest TENS modified neural excitability; however, these changes were not enough to impact clinical function. While TENS may be capable of neuromodulation, it may require rehabilitative exercise to generate lasting changes. NCT04322409. LEVEL OF EVIDENCE Level 2.
Collapse
Affiliation(s)
- Alan R Needle
- Department of Public Health & Exercise Science, Appalachian State University, Boone, NC, USA; Department of Rehabilitation Sciences, Appalachian State University, Boone, NC, USA.
| | - Jennifer E Tinsley
- Department of Athletic Training and Clinical Nutrition, University of Kentucky, Lexington, KY, USA
| | - Jasmine J Cash
- Department of Health Sciences and Research, Medical University of South Carolina, Charleston, SC, USA
| | - Blake K Koeval
- Department of Public Health & Exercise Science, Appalachian State University, Boone, NC, USA
| | - Jacob A Barton
- Department of Public Health & Exercise Science, Appalachian State University, Boone, NC, USA
| | - Jennifer S Howard
- Department of Rehabilitation Sciences, Appalachian State University, Boone, NC, USA
| |
Collapse
|
3
|
Spinal Reflex Excitability of Lower Leg Muscles Following Acute Lateral Ankle Sprain: Bilateral Inhibition of Soleus Spinal Reflex Excitability. Healthcare (Basel) 2022; 10:healthcare10071171. [PMID: 35885698 PMCID: PMC9315602 DOI: 10.3390/healthcare10071171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/16/2022] [Accepted: 06/21/2022] [Indexed: 12/22/2022] Open
Abstract
Neural changes in the ankle stabilizing muscles following ankle sprains are thought to be one contributing factor to persistent ankle dysfunction. However, empirical evidence is limited. Therefore, we aimed to examine spinal reflex excitability of lower leg muscles following acute ankle sprains (AAS). We performed a case-control study with 2 groups consisting of 30 young adults with AAS and 30 aged-matched uninjured controls. Hoffmann reflex (H-reflex) testing was performed to estimate spinal reflex excitability of lower leg muscles: soleus, fibularis longus (FL), tibialis anterior (TA). Maximal H-reflex (Hmax) and motor responses (Mmax) were determined by delivering a series of electrical stimuli at the sciatic nerve. Hmax/Mmax ratios were calculated to represent normalized spinal reflex excitability. Separate group-by-limb analyses of variance (ANOVA) with repeated measures found there were no significant interactions for any of the muscles (SL: F1,56 = 0.95, p = 0.33, FL: F1,51 = 0.65, p = 0.42, TA: F1,51 = 1.87, p = 0.18), but there was a significant main effect of group in the soleus (F1,56 = 6.56, p = 0.013), indicating the Hmax/Mmax ratio of soleus in the AAS group was significantly lower bilaterally (AAS = 0.56 ± 0.19, control = 0.68 ± 0.17, p = 0.013), with no significant group differences in the other muscles (FL: F1,51 = 0.26, p = 0.61, TA: F1,51 = 0.93, p = 0.34). The bilateral inhibition of the soleus spinal reflex excitability following AAS may be significant in that it may explain bilateral sensorimotor deficits (postural control deficits) following unilateral injury, and provide insights into additional therapies aimed at the neural change.
Collapse
|
4
|
Cash JJ, van Werkhoven H, Cole KJ, Needle AR. The effects of 72 h of dynamic ankle immobilization on neural excitability and lower extremity kinematics. Gait Posture 2022; 93:198-204. [PMID: 35183836 DOI: 10.1016/j.gaitpost.2022.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/20/2022] [Accepted: 02/09/2022] [Indexed: 02/02/2023]
Abstract
BACKGROUND Ankle injuries can foster maladaptive changes in nervous system function that predisposes patients to subsequent injury. Patients are often placed in a dynamic boot immobilizer (BI) following injury; however, little is known about the effects of this treatment on neuromechanical function. RESEARCH QUESTION We aimed to determine the effect of 72 h of BI-use on neural excitability and lower extremity joint motion in a healthy cohort. METHODS Twelve uninjured individuals (20.8 ± 1.4 yrs, 1.7 ± 0.1 m, 75.2 ± 9.9 kg) participated in this crossover study. Neural excitability and lower extremity kinematics were assessed before and after 72 h of BI or compression sock (CS) use. Neural excitability was assessed via the Hoffmann (H) reflex and transcranial magnetic stimulation of the motor cortex by measuring muscle activation at the tibialis anterior, peroneus longus, and soleus of the immobilized extremity. Three-dimensional lower extremity joint angles were assessed while participants walked on a treadmill. Repeated-measures analyses of variance detected changes in neural excitability and peak joint angles across time-points and testing conditions, while statistical parametric mapping (SPM) was implemented to determine continuous joint angle changes (α = 0.05). RESULTS Pre-BI to post-BI, HMax:MMax ratio (F = 6.496; p = 0.031) significantly decreased. The BI did not alter resting motor threshold (F = 0.601; p = 0.468), or motor evoked potential amplitudes (F > 2.82; p > 0.608). Significant changes in peak knee and hip angles in the frontal and transverse planes were observed (p < 0.05), with no changes at the ankle. SPM analyses revealed significant hip and knee changes in range of motion (p < 0.05). SIGNIFICANCE Decreased measures of reflex but not corticospinal excitability suggest that BI-use for 72 h unloaded the joint enough to generate peripheral changes, but not the CNS, as has been described in casting models. Further, kinematic changes were observed in proximal lower extremity joints, likely due to swing-phase adaptations while wearing the BI.
Collapse
Affiliation(s)
- Jasmine J Cash
- Department of Health Sciences and Research, Medical University of South Carolina, Charleston, SC, USA.
| | - Herman van Werkhoven
- Department of Health and Exercise Science, Appalachian State University, Boone, NC, USA.
| | - Kelly J Cole
- Department of Health and Exercise Science, Appalachian State University, Boone, NC, USA.
| | - Alan R Needle
- Department of Health and Exercise Science, Appalachian State University, Boone, NC, USA.
| |
Collapse
|
5
|
Stirling AM, McBride JM, Merritt EK, Needle AR. Nervous system excitability and joint stiffness following short-term dynamic ankle immobilization. Gait Posture 2018; 59:46-52. [PMID: 28987766 DOI: 10.1016/j.gaitpost.2017.09.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 09/18/2017] [Accepted: 09/22/2017] [Indexed: 02/02/2023]
Abstract
Joint immobilization has been demonstrated to modify neural excitability in subsets of healthy populations, leading to disinhibition of cortical and reflexive pathways. However, these findings may have limited clinical application as most models have investigated casting and rigid immobilization, while many musculoskeletal injuries often utilize dynamic immobilization devices such as boot immobilizers and pneumatic splints that allow for modified ambulation. We therefore aimed to determine the short-term effects of ambulation in ankle immobilization devices on nervous system excitability and stiffness in able-bodied individuals. A repeated-measures design was implemented where 12 healthy individuals were tested for cortical excitability to the ankle musculature using transcranial magnetic stimulation, reflexive excitability using the Hoffmann reflex, and ankle joint stiffness using arthrometry before and after 30min of ambulation with a boot immobilizer, pneumatic leg splint, or barefoot. Motor evoked potential (MEP), cortical silent period (CSP), Hmax to Mmax ratio, and ankle joint displacement were extracted as dependent variables. Results indicated that despite the novel motor demands of walking in immobilization devices, no significant changes in cortical excitability (F≥0.335, P≥0.169), reflexive excitability (F≥0.027, P≥0.083), or joint stiffness (F≥0.558, P≥0.169) occurred. These findings indicate that short-term ambulation in dynamic immobilization devices does not modify neural excitability despite forced constraints on the sensorimotor system. We may therefore conclude that modifications to neural excitability in previous immobilization models are mediated by long-term nervous system plasticity rather than acute mechanisms, and there appear to be no robust changes in corticomotor or spinal excitability acutely posed by ambulation with immobilization devices.
Collapse
Affiliation(s)
- Alyssa M Stirling
- Department of Health & Exercise Science, Appalachian State University, Boone, NC, USA
| | - Jeffrey M McBride
- Department of Health & Exercise Science, Appalachian State University, Boone, NC, USA
| | - Edward K Merritt
- Department of Kinesiology, Southwestern University, Georgetown, TX, USA
| | - Alan R Needle
- Department of Health & Exercise Science, Appalachian State University, Boone, NC, USA.
| |
Collapse
|
6
|
Needle AR, Baumeister J, Farquhar WB, Greaney JL, Higginson JS, Kaminski TW, Swanik CB. The relationship between the sensory responses to ankle-joint loading and corticomotor excitability. Int J Neurosci 2017; 128:435-441. [DOI: 10.1080/00207454.2017.1396219] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Alan R. Needle
- Department of Health & Exercise Science, Appalachian State University, Boone, NC, USA
| | - Jochen Baumeister
- Exercise & Neuroscience Unit, Institute of Health, Nutrition, and Sports Sciences, Europa-Universität Flensburg, Flensburg, Germany
| | - William B. Farquhar
- Department of Kinesiology & Applied Physiology, University of Delaware, Newark, DE, USA
| | - Jody L. Greaney
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA
| | - Jill S. Higginson
- Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Thomas W. Kaminski
- Department of Kinesiology & Applied Physiology, University of Delaware, Newark, DE, USA
| | - C. Buz Swanik
- Department of Kinesiology & Applied Physiology, University of Delaware, Newark, DE, USA
| |
Collapse
|
7
|
Vie B, Gomez N, Brerro-Saby C, Weber JP, Jammes Y. Changes in stationary upright standing and proprioceptive reflex control of foot muscles after fatiguing static foot inversion. J Biomech 2013; 46:1676-82. [PMID: 23672950 DOI: 10.1016/j.jbiomech.2013.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 04/04/2013] [Accepted: 04/08/2013] [Indexed: 10/26/2022]
Abstract
We searched for the consequences of a maximal static foot inversion sustained until exhaustion on the post-exercise stationary upright standing and the proprioceptive control of the foot muscles. Twelve healthy subjects executed an unilateral maximal static foot inversion during which continuous power spectrum analyses of surface electromyograms of the tibialis anterior (TA), peroneus longus (PL), and gastrocnemius medialis (GM) muscles were performed. Superimposed pulse trains (twitch interpolation) were delivered to the TA muscle to identify "central" or "peripheral" fatigue. Before and after the fatiguing task, we measured (1) the repartition of the plantar and barycentre surfaces with a computerized stationary platform, (2) the peak contractile TA response to electrical stimulation (TA twitch), (3) the tonic vibratory response (TVR) of TA and GM muscles, and (4) the Hoffman reflex. During static exercise, "central" fatigue was diagnosed in 5/12 subjects whereas in the 7 others "peripheral" TA fatigue was deduced from the absence of response to twitch interpolation and the post-exercise decrease in twitch amplitude. The sustained foot inversion was associated with reduced median frequency in TA but not in PL and GM muscles. After static exercise, in all subjects both the mean plantar and rearfoot surfaces increased, indicating a foot eversion, the TVR amplitude decreased in TA but did not vary in GM, and the Hoffman reflex remained unchanged. Whatever was the mechanism of fatigue during the maximal foot inversion task, the facilitating myotatic reflex was constantly altered in foot invertor muscles. This could explain the prevailing action of the antagonistic evertor muscles.
Collapse
Affiliation(s)
- Bruno Vie
- Ecole de Podologie de Marseille, Marseille, France
| | | | | | | | | |
Collapse
|
8
|
Hayes BT, Hicks-Little CA, Harter RA, Widrick JJ, Hoffman MA. Intersession reliability of Hoffmann reflex gain and presynaptic inhibition in the human soleus muscle. Arch Phys Med Rehabil 2010; 90:2131-4. [PMID: 19969180 DOI: 10.1016/j.apmr.2009.07.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Revised: 07/06/2009] [Accepted: 07/07/2009] [Indexed: 11/28/2022]
Abstract
UNLABELLED Hayes BT, Hicks-Little CA, Harter RA, Widrick JJ, Hoffman MA. Intersession reliability of Hoffmann reflex gain and presynaptic inhibition in the human soleus muscle. OBJECTIVE To determine the day-to-day reliability of Hoffmann reflex (H-reflex) gain and presynaptic inhibition of spinal reflexes in the human soleus muscle. DESIGN Controlled trial. SETTING Research laboratory. PARTICIPANTS Volunteers (N=30; mean +/- SD age, 23.4+/-3.9y; height, 175.64+/-10.87cm; mass, 84.50+/-24.18kg) with no history of lower extremity pathology and/or injury participated. INTERVENTIONS Subjects lay prone with the head, shoulders, arms, and hips supported in a static position by a massage body pillow and the ankle positioned at 90 degrees . Recording electrodes were placed over the soleus and tibialis anterior muscle bellies, and the stimulating electrodes were positioned over the tibial nerve in the popliteal space and the common peroneal nerve near the fibular head. MAIN OUTCOME MEASURES The H-reflex and motor wave recruitment curves were then measured and recorded. Presynaptic inhibition was also assessed in the soleus muscle, and a conditioning stimulation of the common peroneal nerve (1 x motor threshold = motor threshold) was used prior to soleus H-reflex measurement. Two testing sessions took place between 2 and 7 days, and each session occurred at the same time of day. RESULTS Assessments of H-reflex gain and presynaptic inhibition yielded test-retest reliability of R equal to . 95 and .91, respectively. CONCLUSIONS Measures of presynaptic inhibition and H-reflex gain (H slope/M slope) in the human soleus muscle are consistent and reliable day to day.
Collapse
Affiliation(s)
- Bradley T Hayes
- Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA.
| | | | | | | | | |
Collapse
|
9
|
Palmieri-Smith RM, Hopkins JT, Brown TN. Peroneal activation deficits in persons with functional ankle instability. Am J Sports Med 2009; 37:982-8. [PMID: 19270189 DOI: 10.1177/0363546508330147] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Functional ankle instability (FAI) may be prevalent in as many as 40% of patients after acute lateral ankle sprain. Altered afference resulting from damaged mechanoreceptors after an ankle sprain may lead to reflex inhibition of surrounding joint musculature. This activation deficit, referred to as arthrogenic muscle inhibition (AMI), may be the underlying cause of FAI. Incomplete activation could prevent adequate control of the ankle joint, leading to repeated episodes of instability. HYPOTHESIS Arthrogenic muscle inhibition is present in the peroneal musculature of functionally unstable ankles and is related to dynamic peroneal muscle activity. STUDY DESIGN Cross-sectional study; Level of evidence, 3. METHODS Twenty-one (18 female, 3 male) patients with unilateral FAI and 21 (18 female, 3 male) uninjured, matched controls participated in this study. Peroneal maximum H-reflexes and M-waves were recorded bilaterally to establish the presence or absence of AMI, while electromyography (EMG) recorded as patients underwent a sudden ankle inversion perturbation during walking was used to quantify dynamic activation. The H:M ratio and average EMG amplitudes were calculated and used in data analyses. Two-way analyses of variance were used to compare limbs and groups. A regression analysis was conducted to examine the association between the H:M ratio and the EMG amplitudes. RESULTS The FAI patients had larger peroneal H:M ratios in their nonpathological ankle (0.399 +/- 0.185) than in their pathological ankle (0.323 +/- 0.161) (P = .036), while no differences were noted between the ankles of the controls (0.442 +/- 0.176 and 0.425 +/- 0.180). The FAI patients also exhibited lower EMG after inversion perturbation in their pathological ankle (1.7 +/- 1.3) than in their uninjured ankle (EMG, 3.3 +/- 3.1) (P < .001), while no differences between legs were noted for controls (P > .05). No significant relationship was found between the peroneal H:M ratio and peroneal EMG (P > .05). CONCLUSION Arthrogenic muscle inhibition is present in the peroneal musculature of persons with FAI but is not related to dynamic muscle activation as measured by peroneal EMG amplitude. Reversing AMI may not assist in protecting the ankle from further episodes of instability; however dynamic muscle activation (as measured by peroneal EMG amplitude) should be restored to maximize ankle stabilization. Dynamic peroneal activity is impaired in functionally unstable ankles, which may contribute to recurrent joint instability and may leave the ankle vulnerable to injurious loads.
Collapse
Affiliation(s)
- Riann M Palmieri-Smith
- School of Kinesiology, University of Michigan, 401 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
| | | | | |
Collapse
|
10
|
Armstrong WJ, Nestle HN, Grinnell DC, Cole LD, Van Gilder EL, Warren GS, Capizzi EA. The Acute Effect of Whole-Body Vibration on the Hoffmann Reflex. J Strength Cond Res 2008; 22:471-6. [DOI: 10.1519/jsc.0b013e3181660605] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
11
|
Sefton JM, Hicks-Little CA, Koceja DM, Cordova ML. Effect of inversion and ankle bracing on peroneus longus Hoffmann reflex. Scand J Med Sci Sports 2008; 17:539-46. [PMID: 17076833 DOI: 10.1111/j.1600-0838.2006.00593.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This study examined peroneus longus (PL) Hoffmann reflex (H-reflex) during sudden inversion perturbation of the ankle/foot complex under an ankle brace and non-brace condition. Ten healthy subjects volunteered. H-reflexes were tested on the up-sloping portion of the recruitment curve, utilizing a control trial M-wave above motor threshold to maintain consistency between subjects and conditions. The PL H/maximum M-wave (M(max)) ratio was established using the PL H-reflex and PL M(max) peak-to-peak measures. The mean ratio across five trials for each subject under each ankle brace (brace, no brace) and surface (flat, inversion) conditions was utilized for analysis. The 1 x 4 repeated measures ANOVA revealed a significant main effect for treatment condition (P<0.0001). The PL H/M(max) ratio significantly increased during sudden inversion-no ankle brace condition compared with the flat surface no-ankle brace condition (P=0.04). Application of an ankle brace had no effect on PL H/M(max) ratio during inversion (P=0.78). During this study PL H/M(max) ratios increased during an inversion perturbation in healthy ankles. This is believed to occur due to heightened sensorimotor demand placed on the nervous system during this motion. Moreover, application of an ankle brace during inversion does not appear to affect PL H/M(max) ratio.
Collapse
Affiliation(s)
- J M Sefton
- Biodynamics Research Laboratory, Department of Kinesiology, The University of North Carolina at Charlotte, Charlotte, NC 28223, USA.
| | | | | | | |
Collapse
|