Effects of activation pattern on human skeletal muscle fatigue (original) (raw)
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Archives of Physical Medicine and Rehabilitation, 1997
To identify the stimulation pattern that optimizes the force-time integral produced during isometric contractions of fatigued human skeletal muscle. Twelve healthy subjects with no history of lower extremity orthopedic problems voluntarily participated. The primary findings were that (1) the optimized trains showed augmentation only from fatigued muscles and (2) a simple stimulation pattern, containing one brief (5msec) initial interpulse interval, produced the greatest force-time integrals and rates of rise of force. With muscle fatigue, the rate of rise of force of the constant-frequency train slowed, whereas the rate of rise of force of the optimized trains remained unchanged. This difference in the rate of rise of force may explain why the optimized trains, which take advantage of the catchlike property of skeletal muscle, are able to augment forces from fatigued muscles when compared with the constant-frequency train. These results may have important clinical implications when using brief trains of electric stimulation to aid patients in performing functional movements and contribute to our understanding of the relationship between the activation pattern of a muscle and the force output produced.
Effect of activation frequency and force on low-frequency fatigue in human skeletal muscle
Journal of Applied Physiology
Effects of activation frequency and force on low-frequency fatigue in human skeletal muscle. J. Appl. Physiol. 86(4): 1337-1346, 1999-No comparison of the amount of low-frequency fatigue (LFF) produced by different activation frequencies exists, although frequencies ranging from 10 to 100 Hz have been used to induce LFF. The quadriceps femoris of 11 healthy subjects were tested in 5 separate sessions. In each session, the force-generating ability of the muscle was tested before and after fatigue and at 2, ϳ13, and ϳ38 min of recovery. Brief (6-pulse), constant-frequency trains of 9.1, 14.3, 33.3, and 100 Hz and a 6-pulse, variable-frequency train with a mean frequency of 14.3 Hz were delivered at 1 train/s to induce fatigue. Immediately postfatigue, there was a significant effect of fatiguing protocol frequency. Muscles exhibited greater LFF after stimulation with the 9.1-, 14.3-, and variable-frequency trains. These three trains also produced the greatest mean force-time integrals during the fatigue test. At 2, ϳ13, and ϳ38 min of recovery, however, the LFF produced was independent of the fatiguing protocol frequency. The findings are consistent with theories suggesting two independent mechanisms behind LFF and may help identify the optimal activation pattern when functional electrical stimulation is used. muscle fatigue; electrical stimulation; excitation-contraction coupling 8750-7587/99 $5.00
Effects of stimulation frequency versus pulse duration modulation on muscle fatigue
Journal of Electromyography and Kinesiology, 2008
During functional electrical stimulation (FES), both the frequency and intensity can be increased to increase muscle force output and counteract the effects of muscle fatigue. Most current FES systems, however, deliver a constant frequency and only vary the stimulation intensity to control muscle force. This study compared muscle performance and fatigue produced during repetitive electrical stimulation using three different strategies: (1) constant pulse-duration and stepwise increases in frequency (frequency-modulation); (2) constant frequency and stepwise increases in pulse-duration (pulse-duration-modulation); and (3) constant frequency and pulse-duration (no-modulation). Surface electrical stimulation was delivered to the quadriceps femoris muscles of 12 healthy individuals and isometric forces were recorded. Muscle performance was assessed by measuring the percent changes in the peak forces and force-time integrals between the first and the last fatiguing trains. Muscle fatigue was assessed by measuring percent declines in peak force between the 60 Hz pre-and post-fatigue testing trains. The results showed that frequency-modulation showed better performance for both peak forces and force-time integrals in response to the fatiguing trains than pulse-duration-modulation, while producing similar levels of muscle fatigue. Although frequencymodulation is not commonly used during FES, clinicians should consider this strategy to improve muscle performance.
Influence of electrical stimulation frequency on skeletal muscle force and fatigue
Annals of Physical and Rehabilitation Medicine, 2010
Objective. -The aim of this study is to determine the impact of electrical stimulation frequency on muscle force and fatigue and propose application modalities in regards to sports or clinical rehabilitation training. Methods. -The maximal voluntary contraction (MVC) force of the quadriceps femoris muscle was recorded before, during and after electrical stimulation in 26 healthy adults during 20-minute sessions corresponding to 60 of 5-second contractions separated by 15-second rest periods. Three different frequencies were used: 100, 50 and 20 Hz.
Clinical Neurophysiology, 2007
Objective-Functional electrical stimulation (FES) has not gained widespread application for a number of factors; two of which are rapid muscle fatigue and imprecise control in force. Stimulation intensity is adjusted during FES to overcome the decline in muscle force due to fatigue and precisely control muscle force output. The purpose of this study was to understand the relationship between muscle force output and stimulation intensity and to see how this relationship changes with fatigue.
Electrical Stimulation Frequency and Skeletal Muscle Characteristics: Effects on Force and Fatigue
European Journal of Translational Myology, 2017
This investigation aimed to determine the force and muscle surface electromyography (EMG) responses to different frequencies of electrical stimulation (ES) in two groups of muscles with different size and fiber composition (fast- and slow-twitch fiber proportions) during a fatigue-inducing protocol. Progression towards fatigue was evaluated in the abductor pollicis brevis (APB) and vastus lateralis (VL) when activated by ES at three frequencies (10, 35, and 50Hz). Ten healthy adults (mean age: 23.2 ± 3.0 years) were recruited; participants signed an IRB approved consent form prior to participation. Protocols were developed to 1) identify initial ES current intensity required to generate the 25% maximal voluntary contraction (MVC) at each ES frequency and 2) evaluate changes in force and EMG activity during ES-induced contraction at each frequency while progressing towards fatigue. For both muscles, stimulation at 10Hz required higher current intensity of ES to generate the initial f...
Fatigability and variable-frequency train stimulation of human skeletal muscles
Physical therapy, 2003
The quadriceps femoris (QF) and tibialis anterior (TA) muscles are often activated through the use of electrical stimulation by physical therapists. These 2 muscles are fundamentally different in regard to their fiber-type composition. Whether protocols developed using a given muscle can be applied to another muscle has seldom been questioned, even if they differ in fiber type. The purpose of this study was to test the hypothesis that torque augmentation during variable-frequency train (VFT) stimulation as compared with constant-frequency train (CFT) stimulation in the fatigued state would not differ between these muscles, even though the TA muscle has 50% relatively more slow fibers than the QF muscle relative to each muscle's overall composition. Ten recreationally active men with no history of lower-extremity pathology participated in the study (mean age=25 years, SD=4, range=19-31; mean height=179 cm, SD=5, range=170-188; mean body mass=80 kg, SD=15, range=63-111). The subje...
New look at force-frequency relationship of human skeletal muscle: effects of fatigue
Journal of neurophysiology, 1998
A muscle does not have a unique force-frequency relationship; rather, it is dynamic and depends on the activation history of muscle. The purpose of this study was to investigate the force-frequency relationship of nonfatigued and fatigued skeletal muscle with the use of both catchlike-inducing trains (CITs) that exploited the catchlike property of skeletal muscle and constant-frequency trains (CFTs). Quadriceps femoris muscles were studied during isometric contractions in twelve healthy subjects (5 females, 7 males). Both the peak force and force-time integrals produced in response to each stimulation train were analyzed. Compared with nonfatigued muscles, higher frequencies of activation were needed to produce comparable normalized peak forces when the muscles were fatigued (i.e., a "rightward" shift in the force-frequency relationship) for both the CFTs and the CITs. When using the normalized force-time integral to measure muscle performance, the CFTs required slightly h...
Physical therapy, 1990
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...
Physical Therapy, 1992
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