Papers by Stuart Binder-macleod
Physical Therapy
The pulpose of this study was to identzh the changes in the force-j-equency relationship (FFR) of... more The pulpose of this study was to identzh the changes in the force-j-equency relationship (FFR) of the human quudriceps femuris muscle following electrically and voluntarily induced fatigue. Twenty nondkabled subjects each participated in one experimental session to test the effects of electrically induced fatigue on the FFR; 10 of these subjects participated in a second session in which voluntanly induced fatigue was produced. Fatigue was induced by having subjects perform repeated, 8-second, isometric contractions followed by 12-second rests until 50% of the initial force was produced. Markedly decreased forces were seen at all frequencies tested following fatigue. Low frequency fatigue was obserued following both fatiguing protocok. n e freguencies needed to produce near-maximum forces did not shift with fatigue. These results suggest that the most appropriate stimulation frequency to use when activating skeletal muscle depends o n both the percentage of tetanic force desired and the fatigue state of the muscle. This study ako provides the clinician with data o n the FFR of healthy human quudnLeps fernoris muscle prior to fatigue. [Binder-Macleod SA, McDemzorui LR. Changes in the force-frequency relationship of the human quudriceps femoris muscle following electrically and voluntanly induced fatigue. Phys Ther. 1992; 72:95-104.1
Advances in Experimental Medicine and Biology, 1995
ABSTRACT
Journal of Applied Physiology
Ding, Jun, Stuart A. Binder-Macleod, and Anthony S. Wexler. Two-step, predictive, isometric force... more Ding, Jun, Stuart A. Binder-Macleod, and Anthony S. Wexler. Two-step, predictive, isometric force model tested on data from human and rat muscles. J. Appl. Physiol. 85(6): 2176-2189, 1998.-Functional electrical stimulation can assist paralyzed individuals to perform functional movements, but muscle fatigue is a major limitation to its practical use. An accurate and predictive mathematical model can facilitate the design of stimulation patterns that optimize aspects of the force transient while minimizing fatigue. Solution nonuniqueness, a major shortcoming in previous work, was overcome with a simpler model. The model was tested on data collected during isometric contractions of rat gastrocnemius muscles and human quadriceps femoris muscles under various physiological conditions. For each condition tested, parameter values were identified using the force response to one or two stimulation trains. The parameterized model was then used to predict forces in response to other stimulation patterns. The predicted forces closely matched the measured forces. The model was not sensitive to initial parameter estimates, demonstrating solution uniqueness. By predicting the force that develops in response to an arbitrary pattern of stimulation, we envision the present model helping identify optimal stimulation patterns for activation of skeletal muscle during functional electrical stimulation. functional electrical stimulation; mathematical model; catchlike property; fatigue; muscle length 8750-7587/98 $5.00
Journal of Applied Physiology
Ding, Jun, Anthony S. Wexler, and Stuart A. Binder-Macleod. Development of a mathematical model t... more Ding, Jun, Anthony S. Wexler, and Stuart A. Binder-Macleod. Development of a mathematical model that predicts optimal muscle activation patterns by using brief trains. J. Appl. Physiol. 88: 917-925, 2000.-Because muscles must be repetitively activated during functional electrical stimulation, it is desirable to identify the stimulation pattern that produces the most force. Previous experimental work has shown that the optimal pattern contains an initial highfrequency burst of pulses (i.e., an initial doublet or triplet) followed by a low, constant-frequency portion. Pattern optimization is particularly challenging, because a muscle's contractile characteristics and, therefore, the optimal pattern change under different physiological conditions and are different for each person. This work describes the continued development and testing of a mathematical model that predicts isometric forces from fresh and fatigued muscles in response to brief trains of electrical pulses. By use of this model and an optimization algorithm, stimulation patterns that produced maximum forces from each subject were identified. functional electrical stimulation; fatigue; human quadriceps femoris muscle; doublets; variable-frequency trains
Journal of Applied Physiology
Ding, Jun, Anthony S. Wexler, and Stuart A. Binder-Macleod. A predictive model of fatigue in huma... more Ding, Jun, Anthony S. Wexler, and Stuart A. Binder-Macleod. A predictive model of fatigue in human skeletal muscles. J Appl Physiol 89: 1322-1332, 2000.-Fatigue is a major limitation to the clinical application of functional electrical stimulation. The activation pattern used during electrical stimulation affects force and fatigue. Identifying the activation pattern that produces the greatest force and least fatigue for each patient is, therefore, of great importance. Mathematical models that predict muscle forces and fatigue produced by a wide range of stimulation patterns would facilitate the search for optimal patterns. Previously, we developed a mathematical isometric force model that successfully identified the stimulation patterns that produced the greatest forces from healthy subjects under nonfatigue and fatigue conditions. The present study introduces a four-parameter fatigue model, coupled with the force model that predicts the fatigue induced by different stimulation patterns on different days during isometric contractions. This fatigue model accounted for 90% of the variability in forces produced by different fatigue tests. The predicted forces at the end of fatigue testing differed from those observed by only 9%. This model demonstrates the potential for predicting muscle fatigue in response to a wide range of stimulation patterns. muscle fatigue; functional electrical stimulation; stimulation pattern; stimulation frequency
Journal of neurophysiology, 1989
1. A relation between stimulation frequency and muscle force is usually determined with stimulus ... more 1. A relation between stimulation frequency and muscle force is usually determined with stimulus trains of constant frequency and described as a single-valued sigmoid curve. This relationship fails to explain a number of features of rate coding. 2. Single motor units were isolated in medial gastrocnemius or soleus muscles of cats deeply anesthetized with pentobarbital sodium. Motor units were classified as fast or slow. Each unit was stimulated with a train whose frequency varied linearly from less than 3 pulses per second (pps) to 20% above the unit's fusion frequency and back to about 3 pps with a period of 5 s. 3. All motor units showed a marked hysteresis during frequency-varying stimulation. A greater force was produced when frequency was decreasing than when it was increasing. The force output of each unit remained nearly maximal as stimulus frequency declined from its maximum to about one-half of the unit's fusion frequency; force rapidly declined with further decreas...
Journal of applied physiology (Bethesda, Md. : 1985), 2000
Fatigue is a major limitation to the clinical application of functional electrical stimulation. T... more Fatigue is a major limitation to the clinical application of functional electrical stimulation. The activation pattern used during electrical stimulation affects force and fatigue. Identifying the activation pattern that produces the greatest force and least fatigue for each patient is, therefore, of great importance. Mathematical models that predict muscle forces and fatigue produced by a wide range of stimulation patterns would facilitate the search for optimal patterns. Previously, we developed a mathematical isometric force model that successfully identified the stimulation patterns that produced the greatest forces from healthy subjects under nonfatigue and fatigue conditions. The present study introduces a four-parameter fatigue model, coupled with the force model that predicts the fatigue induced by different stimulation patterns on different days during isometric contractions. This fatigue model accounted for 90% of the variability in forces produced by different fatigue tes...
Journal of applied physiology (Bethesda, Md. : 1985), 2000
Because muscles must be repetitively activated during functional electrical stimulation, it is de... more Because muscles must be repetitively activated during functional electrical stimulation, it is desirable to identify the stimulation pattern that produces the most force. Previous experimental work has shown that the optimal pattern contains an initial high-frequency burst of pulses (i.e., an initial doublet or triplet) followed by a low, constant-frequency portion. Pattern optimization is particularly challenging, because a muscle's contractile characteristics and, therefore, the optimal pattern change under different physiological conditions and are different for each person. This work describes the continued development and testing of a mathematical model that predicts isometric forces from fresh and fatigued muscles in response to brief trains of electrical pulses. By use of this model and an optimization algorithm, stimulation patterns that produced maximum forces from each subject were identified.
Physical therapy, 1990
The purpose of this study was to determine the effects of a reduction in the pulse frequency on t... more The purpose of this study was to determine the effects of a reduction in the pulse frequency on the fatigue rate of human quadriceps femoris muscle during intermittent (8-second) contractions. Twelve healthy subjects each participated in two experimental sessions. Thirty cycles (cycle time: 8 seconds "on"/12 seconds "off") were applied during each session. During one session, a frequency of 60 pulses per second (pps) was used for all trains. During the other session, the subjects were stimulated with 60 pps for the first train. The stimulating frequency of each train was then progressively reduced, in 5-pps steps, for contractions 2, 3, 5, 8, 12, and 20. By the fifth contraction, the differences in average force produced by the 60-pps trains and the reduced-frequency trains were significant. The difference between the two conditions increased, with the variable-frequency protocol producing 46% more force than the constant-frequency protocol during the last contra...
1. The purpose of this study was to study the effects of a high-frequency burst of pulses at the ... more 1. The purpose of this study was to study the effects of a high-frequency burst of pulses at the onset of a subtetanic train of pulses on the force output of the rat soleus muscle. 2. The soleus muscle was studied in eight rats deeply anesthetized with urethan. The effects of two-, three-, or four-pulse bursts at the onset of subtetanic trains containing a total of 12 pulses were studied in detail. 3. The results showed that two-pulse bursts at the onset of the train produced approximately 20% augmentation in average force and nearly a 50% reduction in the time required to reach a targeted level of force, compared with a comparable 12-pulse subtetanic constant-frequency train; three- or four- pulse bursts produced progressively less additional improvement. In contrast, the two-pulse bursts produced approximately 13% increase in the force-time integral (Area), the three-pulse burst did not significantly further increase the Area gain, and the use of four-pulse bursts markedly decreased the gain in Area. 4. For all three bursts, the observed force augmentation rapidly declined over the 12-pulse trains. Extrapolation beyond the actual data suggested that the force augmentation should last for between approximately 16 and 19 interpulse intervals. 5. To describe the characteristics of the contractile response of the muscle that explains or predicts the amount of force augmentation seen, we made three measurements of the response to the burst of pulses: 1) the peak force produced by the initial burst of pulses (PeakBURST), 2) the force at the time of arrival of the pulse that followed the burst (CatchBURST), and 3) the rise in force produced by the pulse that followed the burst (PotBURST). Of these three measurements, the CatchBURST was the best predictor of the force augmentation seen. 6. The present results showed 1) the importance of the stimulation pattern on the force output of skeletal muscle; 2) that the force-frequency relationship is multivalued, with force depending on both the stimulation history and stimulation frequency; and 3) that a relatively simple discharge strategy, where each train of pulses begins with one or two brief interpulse interval durations, will produce the maximum force from the muscle and result in a predictable force-frequency relationship.
Muscle & Nerve, 2005
The catchlike property of skeletal muscle is the force augmentation produced by the inclusion of ... more The catchlike property of skeletal muscle is the force augmentation produced by the inclusion of an initial, brief, high-frequency burst of two to four pulses at the start of a subtetanic low-frequency stimulation train. Catchlike-inducing trains take advantage of the catchlike property of skeletal muscle and augment muscle performance compared with constant-frequency trains, especially in the fatigued state. Literature spanning more than 30 years has provided comprehensive information about the catchlike property of skeletal muscle. The pattern of the catchlike-inducing train that maximizes muscle performance is fairly similar across different muscles of different species and under various stimulation conditions. This review summarizes the mechanisms of the catchlike property, factors affecting force augmentation, techniques used to identify patterns of catchlike-inducing trains that maximize muscle performance, and potential clinical applications to provide a historical and current perspective of our understanding of the catchlike property.
Medicine & Science in Sports & Exercise, 1995
Quadriceps femoris muscles were studied in 50 healthy subjects to determine the physiological res... more Quadriceps femoris muscles were studied in 50 healthy subjects to determine the physiological responses of the motor units recruited at different force levels during transcutaneous electrical stimulation. During one set of experiments force-frequency relationships were compared at stimulation intensities that produced tetanic contraction of 20%, 50%, or 80% of the maximum voluntary isometric contraction (MVC). No differences in the normalized force-frequency relationship were observed between the 20% and 50% of MVC conditions and only a slight shift to the left was observed at 80% of MVC. The other set of experiments measured the responses to electrically elicited fatigue tests using frequencies of 20, 40, or 60 pps and, at each frequency, intensities that produced 20% or 50% of MVC. Fatigue was greater for the 50% than 20% MVC force conditions. Within each force level fatigue increased with increasing frequency. However, though the differences in the level of recruitment needed to produce the two forces varied for each frequency, the differences in the amount of fatigue produced at each force did not vary between the three stimulation frequencies. This suggests that the fatigue characteristics of the recruited motor units were similar at all intensities tested. We posit, therefore, that the physiological recruitment order during transcutaneous electrical stimulation is less orderly than previously suggested.
Journal of Orthopaedic & Sports Physical Therapy, 1984
ABSTRACT
Journal of Electromyography and Kinesiology, 2003
We previously reported the development of a force-and fatigue-model system that predicted accurat... more We previously reported the development of a force-and fatigue-model system that predicted accurately forces during repetitive fatiguing activation of human skeletal muscles using brief duration (six-pulse) stimulation trains. The model system was tested in the present study using force responses produced by longer duration stimulation trains, containing up to 50 pulses. Our results showed that our model successfully predicted the peak forces produced when the muscle was repetitively activated with stimulation trains of frequencies ranging from 20 to 40 Hz, train durations ranging from 0.5 to 1 s, and varied pulse patterns. The predicted peak forces throughout each protocol matched the experimental peak forces with r 2 values above 0.9 and predicted successfully the forces at the end of each protocol with Ͻ15% error for all protocols tested. The success of our model system further supports its potential use for the design of optimal stimulation patterns for individual users during functional electrical stimulation.
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2002
We have recently developed a force- and fatigue-model system that accurately predicted the effect... more We have recently developed a force- and fatigue-model system that accurately predicted the effect of stimulation frequency on muscle fatigue. The data used to test the model were produced by stimulation trains with resting times of 500 ms. Because the resting times between stimulation trains affect muscle fatigue, this study tested the model's ability to predict the effect of resting times on fatigue. In addition, because this study included different subjects than those used to develop the model, the validity of the model could be tested. Data were collected from human quadriceps femoris muscles using fatigue protocols that included resting times of 500, 750, or 1000 ms. Our results showed that the model predicted fatigue as being a decreasing function of resting time, which was consistent with experimental data. Reliability tests between the experimental data and predictions showed interclass correlation coefficients of 0.97, 0.95, and 0.81 for the initial, final, and percentage decline in peak forces, respectively, suggesting strong agreement between the experimental data and the predictions by the model. The success of our current force- and fatigue-model system helps to validate the model and suggests its potential use in identifying the optimal activation pattern during clinical application of functional electrical stimulation.
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2002
Previously we developed a mathematical force- and fatigue-model system that could predict fatigue... more Previously we developed a mathematical force- and fatigue-model system that could predict fatigue produced by a wide range of frequencies and pulse patterns. However, the models tended to overestimate the forces produced by higher frequency trains. This paper presents modifications to our previously developed force- and fatigue-model system to improve the accuracy in predicting forces during repetitive activation of human skeletal muscle. By comparing the predictions produced by the modified force and fatigue models to those by our previous models, the modification appears to be successful. The current force- and fatigue-model system accounts for about 93% variance in experimental data produced by fatigue protocols consisting of trains with a wide range of frequencies and pulse patterns. In addition, the present models successfully predict the effect of stimulation frequency and pulse pattern on muscle fatigue. The success of our current force- and fatigue-model system suggests its potential use in helping to identify the optimal activation pattern to use during the clinical application of functional electrical stimulation.
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Papers by Stuart Binder-macleod