The authors acknowledge the funding of National Natural Science Fund of China (11572202, 11772201, and 31700815).

Prior to tests, the participants signed an informed consent after receiving information about the experimental process. This experiment has been approved by the ethics committee of Shanghai University of Sports.
1. Equipment setup
<ol>
	<li>Turn on the CDP system, complete self-calibration, and ensure that the instrument operates normally at 100 Hz sampling frequency. 
	NOTE: Each of the two installed independent force plates measures three forces (Fx, Fy, and Fz) and three moments (Mx, My, and Mz). The x-a...

<ol>
	<li>Winter, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+balance+and+posture+control+during+standing+and+walking.">Human balance and posture control during standing and walking.</a> Gait &amp; Posture. 3, 193-214 (1995).</li><li>Vanicek, N., King, S. A., Gohil, R., Chetter, I. C., Coughlin, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computerized+dynamic+posturography+for+postural+control+assessment+in+patients+with+intermittent+claudication.">Computerized dynamic posturography for postural control assessment in patients with intermittent claudication.</a> Journal of Visualized Experiments. (82), e51077 (2013).</li><li>Yin, L., Wang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+Effect+of+Kinesiology+Taping+on+Postural+Stability+in+Individuals+With+Unilateral+Chronic+Ankle+Instability.">Acute Effect of Kinesiology Taping on Postural Stability in Individuals With Unilateral Chronic Ankle Instability.</a> Frontiers in Physiology. 11, 192 (2020).</li><li>Fusco, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+Balance+Evaluation:+Reliability+and+Validity+of+a+Computerized+Wobble+Board.">Dynamic Balance Evaluation: Reliability and Validity of a Computerized Wobble Board.</a> Journal of Strength and Conditioning Research. 34 (6), 1709-1715 (2020).</li><li>Fusco, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wobble+board+balance+assessment+in+subjects+with+chronic+ankle+instability.">Wobble board balance assessment in subjects with chronic ankle instability.</a> Gait &amp; Posture. 68, 352-356 (2019).</li><li>Silva Pde, B., Oliveira, A. 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C., Garascia, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliability+and+validity+of+computerized+force+platform+measures+of+balance+function+in+healthy+older+adults.">Reliability and validity of computerized force platform measures of balance function in healthy older adults.</a> Journal of Geriatric Physical Therapy. 42 (3), 57-66 (2019).</li><li>Doherty, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+incidence+and+prevalence+of+ankle+sprain+injury:+a+systematic+review+and+meta-analysis+of+prospective+epidemiological+studies.">The incidence and prevalence of ankle sprain injury: a systematic review and meta-analysis of prospective epidemiological studies.</a> Sports Medicine. 44 (1), 123-140 (2014).</li><li>Hertel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensorimotor+deficits+with+ankle+sprains+and+chronic+ankle+instability.">Sensorimotor deficits with ankle sprains and chronic ankle instability.</a> Clinics in Sports Medicine. 27 (3), 353-370 (2008).</li><li>Munn, J., Sullivan, S. 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M., Molina-Rueda, F., Lopez-Roman, A., Fernandez-Carnero, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+kinesiology+tape+on+measurements+of+balance+in+subjects+with+chronic+ankle+instability:+a+randomized+controlled+trial.">Effect of kinesiology tape on measurements of balance in subjects with chronic ankle instability: a randomized controlled trial.</a> Archives of Physical Medicine and Rehabilitation. 96 (12), 2169-2175 (2015).</li><li>Jaber, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuromuscular+control+of+ankle+and+hip+during+performance+of+the+star+excursion+balance+test+in+subjects+with+and+without+chronic+ankle+instability.">Neuromuscular control of ankle and hip during performance of the star excursion balance test in subjects with and without chronic ankle instability.</a> PLoS One. 13 (8), 0201479 (2018).</li><li>Simpson, J. D., Stewart, E. M., Macias, D. M., Chander, H., Knight, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Individuals+with+chronic+ankle+instability+exhibit+dynamic+postural+stability+deficits+and+altered+unilateral+landing+biomechanics:+A+systematic+review.">Individuals with chronic ankle instability exhibit dynamic postural stability deficits and altered unilateral landing biomechanics: A systematic review.</a> Phys Ther Sport. 37, 210-219 (2019).</li><li>Gribble, P. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selection+criteria+for+patients+with+chronic+ankle+instability+in+controlled+research:+a+position+statement+of+the+International+Ankle+Consortium.">Selection criteria for patients with chronic ankle instability in controlled research: a position statement of the International Ankle Consortium.</a> Br J Sports Medicine. 48 (13), 1014-1018 (2014).</li><li>Wrisley, D. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Learning+effects+of+repetitive+administrations+of+the+sensory+organization+test+in+healthy+young+adults.">Learning effects of repetitive administrations of the sensory organization test in healthy young adults.</a> Archives of Physical Medicine and Rehabilitation. 88 (8), 1049-1054 (2007).</li><li>Tabard-Foug&#232;re, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EMG+normalization+method+based+on+grade+3+of+manual+muscle+testing:+Within-+and+between-day+reliability+of+normalization+tasks+and+application+to+gait+analysis.">EMG normalization method based on grade 3 of manual muscle testing: Within- and between-day reliability of normalization tasks and application to gait analysis.</a> Gait &amp; Posture. 60, 6-12 (2018).</li><li>Shim, D. B., Song, M. H., Park, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Typical+sensory+organization+test+findings+and+clinical+implication+in+acute+vestibular+neuritis.">Typical sensory organization test findings and clinical implication in acute vestibular neuritis.</a> Auris Nasus Larynx. 45 (5), 916-921 (2018).</li><li>Nam, G. S., Jung, C. M., Kim, J. H., Son, E. 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A., Hertel, J., Denegar, C. 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A., Hale, S. A., Olmsted-Kramer, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simplifying+the+Star+Excursion+Balance+Test+Analyses+of+Subjects+With+and+Without+Chronic+Ankle+Instability.">Simplifying the Star Excursion Balance Test Analyses of Subjects With and Without Chronic Ankle Instability.</a> Journal of Orthopaedic &amp; Sports Physical Therapy. 36 (3), (2006).</li><li>Gribble, P. A., Hertel, J., Plisky, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+the+Star+Excursion+Balance+Test+to+assess+dynamic+postural-control+deficits+and+outcomes+in+lower+extremity+injury:+a+literature+and+systematic+review.">Using the Star Excursion Balance Test to assess dynamic postural-control deficits and outcomes in lower extremity injury: a literature and systematic review.</a> Journal of Athletic Training. 47 (3), 339-357 (2012).</li></ol>

The authors have nothing to disclose.

The presented protocol is used to measure dynamic postural control and related muscle activity in individuals with CAI by synchronizing CDP with sEMG. CDP traces the trajectory of the COP and COG and provides insight into the interaction between sensory information (visual, somatosensory, and vestibular sensation) input and the external environment8,21,22. It is an effective tool for the diagnosis of the functional activity limi...

Computerized dynamic posturography (CDP) is an objective technique for the evaluation of postural stability under static and dynamic conditions and perturbation. CDP is based on the inverted pendulum model that traces the interrelationship between the center of pressure (COP) and the center of gravity (COG). COG is the vertical projection of the center of mass (COM), whereas COM is the point equivalent of the total body mass in the global reference system. COP is the point location of the vertical ground reaction force vector. It represents a weighted average of all the pressures over the surface of the contact area with the ground1. Postural stability is the ability to maintain the COM within the base of support in a given sensory environment. It reflects neuromuscular control ability that coordinates the central nervous system with the afferent sensory system (vision, proprioception, and vestibular sensation) and motor command output2.
Previous evaluation methods for postural control, such as the time for a single-leg stance and the reach distance for Y-balance tests, are results-oriented and cannot be used to objectively evaluate the coordination between sensory systems and motor control3. In addition, some studies used portable computerized wobble board, which quantified dynamic balance performances out of laboratory settings4,5,6. CDP differs from the abovementioned test methods, because it can be applied to the analysis of the proportion of vision, proprioception, and vestibular sensation in postural stability maintenance and to the evaluation of the proportion of motor strategy, such as ankle or hip dominant strategy. It has been viewed as a gold standard for postural control measurement7 because of its accuracy, reliability, and validity8.
Chronic ankle instability (CAI) is characterized by persistent ankle pain, swelling, and feeling of &#8220;giving way&#8221;; it is one of the most common sports injuries9. CAI originates mostly from lateral ankle sprains, which destroy the integrity and stability of the lateral ankle ligament complex. The proprioception, fibular muscle strength, and normal trajectory of talus are impaired10,11. The deficiencies of the weak ankle segment can result in deficient postural control and muscle activation in individuals with CAI12. However, few studies have investigated the postural stability of individuals with CAI by using CDP3,13. Current measurements could rarely analyze the posture control deficiency of CAI from the perspective of sensory analysis. Therefore, the ability of sensory organization and postural strategy of CAI to maintain postural stability needs further exploration.
Muscle activity is an important component of neuromuscular control that affects the regulation of postural stability14,15. However, CDP only monitors the interrelationship between COP and COG through force plates, and its application to the observation of the specific activation level of lower limb muscles in individuals with CAI is difficult. Currently, few studies have evaluated the postural stability of individuals with CAI through a method that combines CDP with electromyography (EMG).
Therefore, the developed protocol aims to explore postural control and related muscle activity by combining CDP and surface electromyography system (sEMG). This protocol provides a novel approach to investigate neuromuscular control, including sensory organization, postural control, and related muscle activity, for participants with CAI.

<table>
	<tbody>
		<tr>
			<td>NeuroCom Balance Manager SMART EquiTest</td>
			<td>Natus Medical Incorporated, USA</td>
			<td></td>
			<td>Its major components include: NeuroCom Balance Manager Software Suite, dynamic dual force plate (rotate &#38; translate), moveable visual surround with 15&#8221; LCD display (it could provide a real time display of the subject&#8217;s center of gravity shown as a cursor during the task) and illumination, overhead support bar with patient harness, computer and other parts.</td>
		</tr>
		<tr>
			<td>wireless Myon 320 sEMG system</td>
			<td>Myon AG</td>
			<td></td>
			<td>The system consists of 16 parallel channels of transmitter signals, receiver, &#34;EMG motion Tools&#34; and &#34;ProEMG&#34; software,computer and other parts.</td>
		</tr>
	</tbody>
</table>

evaluating postural control and lower-extremity muscle activation in individuals with chronic ankle instability

Computerized dynamic posturography (CDP) is an objective technique for the evaluation of postural stability under static and dynamic conditions and perturbation. CDP is based on the inverted pendulum model that traces the interrelationship between the center of pressure and the center of gravity. CDP can be used to analyze the proportions of vision, proprioception, and vestibular sensation to maintain postural stability. The following characters define chronic ankle instability (CAI): persistent ankle pain, swelling, the feeling of &#8220;giving way,&#8221; and self-reported disability. Postural stability and fibular muscle activation level in individuals with CAI decreased due to lateral ankle ligament complex injuries. Few studies have used CDP to explore the postural stability of individuals with CAI. Studies that investigate postural stability and related muscle activation by using synchronized CDP with surface electromyography are lacking. This CDP protocol includes a sensory organization test (SOT), a motor control test (MCT), and an adaption test (ADT), as well as tests that measure unilateral stance (US) and limit of stability (LOS). The surface electromyography system is synchronized with CDP to collect data on lower limb muscle activation during measurement. This protocol presents a novel approach for evaluating the coordination of the visual, somatosensory, and vestibular systems and related muscle activation to maintain postural stability. Moreover, it provides new insights into the neuromuscular control of individuals with CAI when coping with real complex environments.

Representative CDP Results 
Sensory organization test 
The system evaluates the participant&#8217;s ability to maintain COG in the predetermined target area, when the environment changes as the peripheral signal input. Equilibrium score (ES) is the score under conditions 1&#8211;6 that reflects the ability to coordinate the sensory system to maintain postural stability (Equation 6). The composite score (COMP) is the weighted average score of al...

Watch this Scientific Journal Video about Evaluating Postural Control and Lower-extremity Muscle Activation in Individuals with Chronic Ankle Instability at JoVE.com

Evaluating Postural Control and Lower-extremity Muscle Activation in Individuals with Chronic Ankle Instability

Individuals with chronic ankle instability (CAI) exhibit postural control deficiency and delayed muscle activation of lower extremities. Computerized dynamic posturography combined with surface electromyography provides insights into the coordination of the visual, somatosensory, and vestibular systems with muscle activation regulation to maintain postural stability in individuals with CAI.

Computerized dynamic posturography (CDP) is an objective technique for the evaluation of postural stability under static and dynamic conditions and ...

This protocol presents a novel approach for evaluating the coordination of the visual somata sensory and vestibular systems, and related muscle activation required to maintain postural stability. This technique can be used to perform a comprehensive investigation of the neuromuscular control for chronic ankle instability through the combination of computerized dynamic posturography, and related muscle activity. This method could also be used to explore postural stability and related muscle activity in other conditions such as neurologic or musculoskeletal system disorders.Before beginning an analysis, turn on the CDP system and complete a self-calibration to confirm that the instrument is operating at a 100 Hertz sampling frequency. In the software, double-click Balance Manager System, Clinical Module, and New Patient. Input the participant name, height, ID, weight, and age, and select Assessment, Sensory Organization Test, Motor Control Test, Adaption Test, Limits of Stability, and Unilateral Stance.Turn on the surface EMG system and double click the EMG motion tools icon. Specify the trigger signals and establish the participant ID.And place one wireless electrode onto the belly of each lower extremity muscle to be measured. Then use the synchronization line to connect the surface EMG system with the CDP system, and adjust the surface EMG system camera to capture the signal indicator light of the CDP system.When both systems are ready, use a safety harness to fix the participant to the support bar, and carefully align the participant's bare feet with the force plates so that the participant is facing the visual surround. Then turn off the screen embedded in the visual surround. To conduct a sensory organization test, instruct the participant to stand upright with their center of gravity as stable as possible, and have the participant complete each test three times for 20 seconds per test under each condition as indicated in the table.For a unilateral stance analysis, instruct the participant to place their hands on the anterior superior iliac spine with their eyes open and to consider the unstable ankle side as the support leg. Have the participant fully extend and bend the knee joint of their non supporting leg by approximately 30 degrees while standing stably for 10 seconds. After the third trial, have the participant repeat the same measurement with their eyes closed.For a limit of stability test, instruct the participant to maintain their center of gravity in the central area until they hear a ring sound, at which point the participant should lean their body and quickly shift their center of gravity into the targeted frame in one of eight directions in the screen for 10 seconds. To conduct a motor control test, instruct the participant to restore their body stability in response to the unexpected slipping of the force plates. To perform an adaption test, instruct the participant to restore their body stability by directing the toes upward or downward in response to five consecutive unexpected rotations at a 20 degree per second velocity.When all of the tests have been completed in the processing window of the surface EMG software import the CD3 file of the EMG raw data and MP4 file of the light video. In the processing pipeline operations, set the Butterworth filter with low pass to 450 Hertz and an order of two, the high pass to 20 Hertz with an order of two, the notch filter to 50 Hertz, and the root mean square smoothing window to 100 milliseconds. In the Generates Events tab, set all channels go above five X baseline noise standard deviations for at least 50 milliseconds to muscle on, and all channels drop below five X standard deviations over baseline for at least 50 milliseconds to muscle off.Then in the Generate Parameters tab, select integral electromyography, root mean square, mean power frequency, medium frequency. In this analysis, as indicated by the green bars, the participant was able to better coordinate their three sensory systems and to more effectively respond than their age matched normative counterpoint in the dataset. Using their vision, proprioception, and vestibule sensory sensations to maintain balance throughout the sensory analysis.The participant mainly relied on the ankle strategy and their ability to maintain postural stability. The total swing between the left and right legs was normal both when the participant's eyes were open and when they were closed. The participant exhibited a delayed reaction time between the sending of the move signal and the beginning of body movement, but a normal movement velocity.For the forward and right end point excursions, the movement distance of the center of gravity did not reach the normal range. The maximum distance of the center of gravity movement was normal however. The participant demonstrated a normal weight distribution but an abnormal backward displacement response suggesting a unilateral orthopedic injury.In addition, the increase in amplitude scaling was bipedaly symmetrical in relation to the amplitudes of the force plate slippage, and the sway energy score was normal. Be sure to accurately input the participant's age, height, and weight, and to correctly align the foot positions, as these parameters determine the location of the CDP and affect the postural analysis.

evaluating-postural-control-lower-extremity-muscle-activation

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JoVE Journal

Neuroscience

8.1K visualizações.  Tongji University. Este protocolo apresenta uma nova abordagem para avaliar a coordenação dos sistemas sensoriais e vestibulares somata visual, e ativação muscular relacionada necessária para manter a estabilidade postural. Esta técnica pode ser usada para realizar uma investigação abrangente do controle neuromuscular para instabilidade crônica do tornozelo através da combinação de posturografia dinâmica computadorizada e atividade muscular relacionada. Este método também poderia ser usado para e...