A phenomenological model that predicts forces generated when electrical stimulation is superimposed on submaximal volitional contractions

Superimposition of electrical stimulation during voluntary contractions is used to produce functional movements in individuals with central nervous system impairment, to evaluate the ability to activate a muscle, to characterize the nature of fatigue, and to improve muscle strength during postsurgical rehabilitation. Currently, the manner in which voluntary contractions and electrically elicited forces summate is not well understood. The objective of the present study is to develop a model that predicts the forces obtained when electrical stimulation is superimposed on a volitional contraction. Quadriceps femoris muscles of 12 able-bodied subjects were tested. Our results showed that the total force produced when electrical stimulation was superimposed during a volitional contraction could be modeled by the equation T = V + S[(MaxForce − V)/MaxForce]N, where T is the total force produced, V is the force in response to volitional contraction alone, S is the force response to the electrical stimulation alone, MaxForce is the maximum force-generating ability of the muscle, and N is a parameter that we posit depends on the differences in the motor unit recruitment order and firing rates between volitional and electrically elicited contractions. In addition, our results showed that the model predicted accurately (intraclass correlation coefficient ≥0.97) the total force in response to a wide range of stimulation intensities and frequencies superimposed on a wide range of volitional contraction levels. Thus the model will be helpful to clinicians and scientists to predict the amount of stimulation needed to produce the targeted force levels in individuals with partial paralysis.

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Development and Validation of a New Scoring Tool to Evaluate the Clinical Evolution of Adult Patients with Nonsegmental Vitiligo

Dermatology ◽

10.1159/000511890 ◽

2021 ◽

pp. 1-9

Author(s):

María Luisa Peralta-Pedrero ◽

Denisse Herrera-Bringas ◽

Karla Samantha Torres-González ◽

Martha Alejandra Morales-Sánchez ◽

Fermín Jurado Santa-Cruz ◽

...

Keyword(s):

Body Surface ◽

Task Force ◽

Intraclass Correlation ◽

The Body ◽

Response To Treatment ◽

Similar Response ◽

Clinical Evolution ◽

Wide Range ◽

Patient Reported ◽

Extreme Groups

Background: Vitiligo has an unpredictable course and a variable response to treatment. Furthermore, the improvement of some vitiligo lesions cannot be considered a guarantee of a similar response to the other lesions. Instruments for patient-reported outcome measures (PROM) can be an alternative to measure complex constructions such as clinical evolution. Objective: The aim of this study was to validate a PROM that allows to measure the clinical evolution of patients with nonsegmental vitiligo in a simple but standardized way that serves to gather information for a better understanding of the disease. Methods: The instrument was created through expert consensus and patient participation. For the validation study, a prospective cohort design was performed. The body surface area affected was measured with the Vitiligo Extension Score (VES), the extension, the stage, and the spread by the evaluation of the Vitiligo European Task Force assessment (VETFa). Reliability was determined with test-retest, construct validity through hypothesis testing, discriminative capacity with extreme groups, and response capacity by comparing initial and final measurements. Results: Eighteen semi-structured interviews and 7 cognitive interviews were conducted, and 4 dermatologists were consulted. The instrument Clinical Evolution-Vitiligo (CV-6) was answered by 119 patients with a minimum of primary schooling. A wide range was observed in the affected body surface; incident and prevalent cases were included. The average time to answer the CV-6 was 3.08 ± 0.58 min. In the test-retest (n = 53), an intraclass correlation coefficient was obtained: 0.896 (95% CI 0.82–0.94; p < 0.001). In extreme groups, the mean score was 2 (2–3) and 5 (4–6); p < 0.001. The initial CV-6 score was different from the final one and the change was verified with VES and VETFa (p < 0.05, n = 92). Conclusions: The CV-6 instrument allows patient collaboration, it is simple and brief, and it makes it easier for the doctor to focus attention on injuries that present changes at the time of medical consultation.

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Test Re-test Reliability of Single and Multijoint Strength Properties in Female Australian Footballers

Sports Medicine - Open ◽

10.1186/s40798-020-00292-5 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Daniel Kadlec ◽

Matthew J. Jordan ◽

Leanne Snyder ◽

Jacqueline Alderson ◽

Sophia Nimphius

Keyword(s):

Knee Flexion ◽

Intraclass Correlation ◽

Strength Properties ◽

Peak Force ◽

Test Reliability ◽

Leg Extension ◽

Hip Abduction ◽

Hip Flexion ◽

Voluntary Contractions ◽

Trunk Position

Abstract Purpose To examine the test re-test reliability of isometric maximal voluntary contractions (MVC) of hip adduction (ADDISO), hip abduction (ABDISO), and multijoint leg extension (SQUATISO) in sub-elite female Australian footballers. Methods Data were collected from 24 sub-elite female Australian footballers (age 22.6 ± 4.5 years; height 169.4 ± 5.5 cm; body mass 66.6 ± 8.0 kg; 4.5 ± 4.4 years sport-specific training; 2.5 ± 2.0 years unstructured resistance training) from the same club on two non-consecutive days. Participants performed three isometric MVCs of ADDISO, ABDISO, and SQUATISO. The SQUATISO was performed at 140° knee flexion with a vertical trunk position and ADDISO and ABDISO measures were performed in a supine position at 60° of knee flexion and 60° hip flexion. Reliability was assessed using paired t tests and the intraclass correlation coefficient (ICC) with 95% confidence intervals (CI), typical error (TE), and coefficient of variation (CV%) with 95% CI. Results SQUATISO peak force (ICC .95; CV% 4.1), ABDISO for left, right, and sum (ICC .90–.92; CV% 5.0–5.7), and ADDISO for left, right, and sum (ICC .86–.91; CV% 6.2–6.9) were deemed acceptably reliable based on predetermined criteria (ICC ≥ .8 and CV% ≤ 10). Conclusion SQUATISO, ABDISO, and ADDISO tests demonstrated acceptable reliability for the assessment of peak force in sub-elite female Australian footballers, suggesting these assessments are suitable for muscle strength testing and monitoring adaptations to training.

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Quadriceps activation during maximal isometric and isokinetic contractions: The minimal real difference and its implications

Isokinetics and Exercise Science ◽

10.3233/ies-203241 ◽

2020 ◽

pp. 1-13

Author(s):

Luigi Catino ◽

Chiara Malloggi ◽

Stefano Scarano ◽

Valeria Cerina ◽

Viviana Rota ◽

...

Keyword(s):

Intraclass Correlation ◽

Correlation Coefficients ◽

Voluntary Activation ◽

Real Difference ◽

Concentric Contractions ◽

Rehabilitation Programs ◽

Logit Transformation ◽

Isokinetic Contractions ◽

Electrical Stimuli ◽

Voluntary Contractions

BACKGROUND: A method of measurement of voluntary activation (VA, percent of full muscle recruitment) during isometric and isokinetic concentric contractions of the quadriceps femoris (QF) at 60∘/s and 120∘/s was previously validated. OBJECTIVE: This study aimed to quantify the test-retest minimal real difference (MRD) of VA during isometric (ISOM) and isokinetic concentric contractions of QF (100∘/s, ISOK) in a sample of healthy individuals. METHODS: VA was measured through the interpolated twitch technique. Pairs of electrical stimuli were delivered to the QF at 40∘ of knee flexion during maximal voluntary contractions. Twenty-five healthy participants (20–38 years, 12 women, 13 men) completed two testing sessions with a 14-day interval. VA values were linearized through logit transformation (VAl). The MRD was estimated from intraclass correlation coefficients (model 2.1). RESULTS: The VA (median, range) was 84.20% (38.2–99.9%) in ISOM and 94.22% (33.8-100%) in ISOK. MRD was 0.78 and 1.12 logit for ISOM and ISOK, respectively. As an example, in terms of percent VA these values correspond to a change from 76% to 95% and from 79% to 98% in ISOM and in ISOK, respectively. CONCLUSIONS: The provided MRD values allow to detect significant individual changes in VA, as expected after training and rehabilitation programs.

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Effects of electrical stimulation on isolated rodent gastric smooth muscle cells evaluated via a joint computational simulation and experimental approach

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00149.2009 ◽

2009 ◽

Vol 297 (4) ◽

pp. G672-G680 ◽

Cited By ~ 17

Author(s):

P. Du ◽

S. Li ◽

G. O'Grady ◽

L. K. Cheng ◽

A. J. Pullan ◽

...

Keyword(s):

Smooth Muscle ◽

Electrical Stimulation ◽

Pulse Train ◽

Pulse Width ◽

Computational Simulation ◽

Minimum Energy ◽

Experimental Studies ◽

Single Pulse ◽

Plateau Phase ◽

Wide Range

Gastric electrical stimulation (GES) involves the delivery of electrical impulses to the stomach for therapeutic purposes. New GES protocols are needed that are optimized for improved motility outcomes and energy efficiency. In this study, a biophysically based smooth muscle cell (SMC) model was modified on the basis of experimental data and employed in conjunction with experimental studies to define the effects of a large range of GES protocols on individual SMCs. For the validation studies, rat gastric SMCs were isolated and subjected to patch-clamp analysis during stimulation. Experimental results were in satisfactory agreement with simulation results. The results define the effects of a wide range of GES parameters (pulse width, amplitude, and pulse-train frequency) on isolated SMCs. The minimum pulse width required to invoke a supramechanical threshold response from SMCs (defined at −30 mV) was 65 ms (at 250-pA amplitude). The minimum amplitude required to invoke this threshold was 75 pA (at 1,000-ms pulse width). The amplitude of the invoked response beyond this threshold was proportional to the stimulation amplitude. A high-frequency train of stimuli (40 Hz; 10 ms, 150 pA) could invoke and maintain the SMC plateau phase while requiring 60% less power and accruing ∼30% less intracellular Ca2+ concentration during the plateau phase than a comparable single-pulse protocol could in a demonstrated example. Validated computational simulations are an effective strategy for efficiently identifying effective minimum-energy GES protocols, and pulse-train protocols may also help to reduce the power consumption of future GES devices.

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Probability-Based Prediction of Activity in Multiple Arm Muscles: Implications for Functional Electrical Stimulation

Journal of Neurophysiology ◽

10.1152/jn.00956.2007 ◽

2008 ◽

Vol 100 (1) ◽

pp. 482-494 ◽

Cited By ~ 9

Author(s):

Chad V. Anderson ◽

Andrew J. Fuglevand

Keyword(s):

Electrical Stimulation ◽

Functional Electrical Stimulation ◽

Muscle Activity ◽

Probability Distributions ◽

Probabilistic Methods ◽

Muscle Stimulation ◽

Implanted Electrodes ◽

Motor Behaviors ◽

Wide Range ◽

Arm Muscles

Functional electrical stimulation (FES) involves artificial activation of muscles with implanted electrodes to restore motor function in paralyzed individuals. The range of motor behaviors that can be generated by FES, however, is limited to a small set of preprogrammed movements such as hand grasp and release. A broader range of movements has not been implemented because of the substantial difficulty associated with identifying the patterns of muscle stimulation needed to elicit specified movements. To overcome this limitation in controlling FES systems, we used probabilistic methods to estimate the levels of muscle activity in the human arm during a wide range of free movements based on kinematic information of the upper limb. Conditional probability distributions were generated based on hand kinematics and associated surface electromyographic (EMG) signals from 12 arm muscles recorded during a training task involving random movements of the arm in one subject. These distributions were then used to predict in four other subjects the patterns of muscle activity associated with eight different movement tasks. On average, about 40% of the variance in the actual EMG signals could be accounted for in the predicted EMG signals. These results suggest that probabilistic methods ultimately might be used to predict the patterns of muscle stimulation needed to produce a wide array of desired movements in paralyzed individuals with FES.

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Distribution of Wave Impact Forces From Breaking and Non-Breaking Waves

Volume 4: Ocean Engineering; Ocean Renewable Energy; Ocean Space Utilization, Parts A and B ◽

10.1115/omae2009-79978 ◽

2009 ◽

Cited By ~ 2

Author(s):

Anne M. Fullerton ◽

Thomas C. Fu ◽

Edward S. Ammeen

Keyword(s):

Free Surface ◽

Wave Height ◽

Breaking Waves ◽

Qualitative Assessment ◽

Total Force ◽

Impact Loads ◽

Wave Impact ◽

Data Set ◽

Wave Characteristics ◽

Wide Range

Impact loads from waves on vessels and coastal structures are highly complex and may involve wave breaking, making these changes difficult to estimate numerically or empirically. Results from previous experiments have shown a wide range of forces and pressures measured from breaking and non-breaking waves, with no clear trend between wave characteristics and the localized forces and pressures that they generate. In 2008, a canonical breaking wave impact data set was obtained at the Naval Surface Warfare Center, Carderock Division, by measuring the distribution of impact pressures of incident non-breaking and breaking waves on one face of a cube. The effects of wave height, wavelength, face orientation, face angle, and submergence depth were investigated. A limited number of runs were made at low forward speeds, ranging from about 0.5 to 2 knots (0.26 to 1.03 m/s). The measurement cube was outfitted with a removable instrumented plate measuring 1 ft2 (0.09 m2), and the wave heights tested ranged from 8–14 inches (20.3 to 35.6 cm). The instrumented plate had 9 slam panels of varying sizes made from polyvinyl chloride (PVC) and 11 pressure gages; this data was collected at 5 kHz to capture the dynamic response of the gages and panels and fully resolve the shapes of the impacts. A Kistler gage was used to measure the total force averaged over the cube face. A bottom mounted acoustic Doppler current profiler (ADCP) was used to obtain measurements of velocity through the water column to provide incoming velocity boundary conditions. A Light Detecting and Ranging (LiDAR) system was also used above the basin to obtain a surface mapping of the free surface over a distance of approximately 15 feet (4.6 m). Additional point measurements of the free surface were made using acoustic distance sensors. Standard and high-speed video cameras were used to capture a qualitative assessment of the impacts. Impact loads on the plate tend to increase with wave height, as well as with plate inclination toward incoming waves. Further trends of the pressures and forces with wave characteristics, cube orientation, draft and face angle are investigated and presented in this paper, and are also compared with previous test results.

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Functional Electrical Stimulation (FES) Control for Restoration and Rehabilitation of Motor Function

Technological Advancements in Biomedicine for Healthcare Applications - Advances in Bioinformatics and Biomedical Engineering ◽

10.4018/978-1-4666-2196-1.ch009 ◽

2012 ◽

pp. 80-93

Author(s):

Takashi Watanabe ◽

Naoto Miura

Keyword(s):

Electrical Stimulation ◽

Motor Function ◽

Functional Electrical Stimulation ◽

Wearable Sensors ◽

Integrated System ◽

Rehabilitation Training ◽

Cord Injury ◽

Feedback Error Learning ◽

Feedback Error ◽

Functional Movements

Functional electrical stimulation (FES) has been studied and clinically applied to restoring or assisting motor functions lost due to spinal cord injury or cerebrovascular disease. Electrical stimulation without control of functional movements is also used for therapy or in rehabilitation training. In recent years, one of the main focuses of FES studies has been its application for rehabilitation of motor function. In this review, the authors first present the basics of applying electrical stimulation to the neuromuscular system for motor control. Then, two methods of FES control are discussed: controllers for FES based on feedback error learning (FEL) and on cycle-to-cycle control of limb movements. The FEL-FES controller can be practical in FES applications that need to control the musculoskeletal system that involves various nonlinear characteristics and delay in its responses to electrical stimulation. The cycle-to-cycle control is expected to be effective in controlling repetitive movements for rehabilitation training. Finally, a study on ankle dorsiflexion control during the swing phase using an integrated system of FES control and motion measurement with wearable sensors for rehabilitation is presented.

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Application of orthoses and neurostimulation in neurorehabilitation

Oxford Textbook of Neurorehabilitation ◽

10.1093/med/9780198824954.003.0032 ◽

2020 ◽

pp. 433-444

Author(s):

Jacopo Carpaneto ◽

Silvestro Micera

Keyword(s):

Electrical Stimulation ◽

Future Trends ◽

Motor Functions ◽

Non Invasive ◽

Combined Use ◽

Invasive Techniques ◽

Functional Movements

Electrical stimulation can allow the recruitment of muscles to achieve functional movements. This approach is therefore very interesting to restore motor functions in subjects who have lost them because of neurological problems. In this chapter the main approaches to restoration of grasping and of locomotor functions using electrical stimulation and also the combined use of electrical stimulation and mechanical orthoses are presented. The potentials and limits related to the use of these different non-invasive or invasive techniques are highlighted and examined. Finally, a brief description of future trends and current limitations is also provided.

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Do Arm Postures Vary With the Speed of Reaching?

Journal of Neurophysiology ◽

10.1152/jn.1999.81.5.2582 ◽

1999 ◽

Vol 81 (5) ◽

pp. 2582-2586 ◽

Cited By ~ 65

Author(s):

Kiisa C. Nishikawa ◽

Sara T. Murray ◽

Martha Flanders

Keyword(s):

Degrees Of Freedom ◽

Three Dimensional ◽

Optimal Solution ◽

Reaching Movements ◽

Total Force ◽

Joint Torques ◽

Dynamic Factors ◽

Human Arm ◽

Wide Range ◽

Dynamic Forces

Do arm postures vary with the speed of reaching? For reaching movements in one plane, the hand has been observed to follow a similar path regardless of speed. Recent work on the control of more complex reaching movements raises the question of whether a similar “speed invariance” also holds for the additional degrees of freedom. Therefore we examined human arm movements involving initial and final hand locations distributed throughout the three-dimensional (3D) workspace of the arm. Despite this added complexity, arm kinematics (summarized by the spatial orientation of the “plane of the arm” and the 3D curvature of the hand path) changed very little for movements performed over a wide range of speeds. If the total force (dynamic + quasistatic) had been optimized by the control system (e.g., as in a minimization of the change in joint torques or the change in muscular forces), the optimal solution would change with speed; slow movements would reflect the minimal antigravity torques, whereas fast movements would be more strongly influenced by dynamic factors. The speed-invariant postures observed in this study are instead consistent with a hypothesized optimization of only the dynamic forces.

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