Perceived effort in force production as reflected in motor-related cortical potentials (original) (raw)
Related papers
2021
PURPOSE: The perception of effort (PE) is widely used to prescribe and monitor exercise during locomotor and resistance tasks. The present study examines the validity of PE to prescribe and monitor exercise during upper-limb motor tasks under various loads and speed requirements.METHODS: Forty participants volunteered in two experiments. In experiment 1, we used four PE intensities to prescribe exercise on a modified version of the box and block test (BBT) and a pointing task. We investigated the possibility of monitoring the exercise intensity by tracking changes in PE rating in response to three different tempos or additional weights. Experiment 2 replicated the possibility of prescribing the exercise with the PE intensity during the BBT and explored the impact of additional weights on performance and PE during the standardized version of the BBT. Muscle activation, heart rate and respiratory frequencies were recorded.RESULTS: In experiment 1, increasing the PE intensity to prescr...
2009
While fatigue is a common daily phenomenon, the exact relationship between perception of effort and fatigue is still unknown. Existing tools for assessing perception of effort are effectively limited to whole body exercise, while current methods for assessing voluntary activation are painful and not feasible for clinical application. The main aims of this thesis were to evaluate existing methodologies for their appropriateness in assessing perception of effort and voluntary activation following isolated muscle function testing, and to examine the relationship between subjective perception of effort and objective changes in the healthy motor control system. The implementation of reliable and valid assessment tools in clinical practice may enable clarification of the pathogenesis of many neurological conditions that have chronic fatigue as a key feature.
Perception of effort reflects central motor command during movement execution
It is thought that perception of effort during physical tasks is the conscious awareness of the central motor command sent to the active muscles. The aim of this study was to directly test this hypothesis by experimentally varying perception of effort and measuring movement-related cortical potential (MRCP). Sixteen healthy, recreationally active men made unilateral dynamic elbow flexions to lift a light (20% one repetition maximum, 1RM) and a heavier (35% 1RM) weight with a fatigued arm and a nonfatigued arm while rating of perceived effort (RPE), biceps brachii electromyogram (EMG), and MRCP were recorded. RPE, EMG amplitude, and MRCP amplitude at Cz during weight raising increased with weight and with muscle fatigue. There was a significant correlation between RPE and MRCP amplitude at the vertex during the weight raising epoch. This study provides direct neurophysiological evidence that perception of effort correlates with central motor command during movement execution.
Exploring the relationship between effort perception and poststroke fatigue
Neurology, 2020
ObjectiveTo test the hypothesis that poststroke fatigue, a chronic, pathologic fatigue condition, is driven by altered effort perception.MethodsFifty-eight nondepressed, mildly impaired stroke survivors with varying severity of fatigue completed the study. Self-reported fatigue (trait and state), perceived effort (PE; explicit and implicit), and motor performance were measured in a handgrip task. Trait fatigue was measured with the Fatigue Severity Scale-7 and Neurologic Fatigue Index. State fatigue was measured with a visual analog scale (VAS). Length of hold at target force, overshoot above target force, and force variability in handgrip task were measures of motor performance. PE was measured with a VAS (explicit PE) and line length estimation, a novel implicit measure of PE.ResultsRegression analysis showed that 11.6% of variance in trait fatigue was explained by implicit PE (R = 0.34; p = 0.012). Greater fatigue was related to longer length of hold at target force (R = 0.421, p...
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2014
Hand-based human-machine interfaces are complex tasks that involve repetitive or sustained movements and postures of the hands that can lead to overuse syndromes of the musculoskeletal system. Consequently, it is important to minimize the physical effort that occurs at these interfaces. The evaluation of physical effort can be performed either by subjective evaluation of the relative perceived effort (e.g., Borg scale) or by objective physiological measurements (e.g., electromyography -EMG). However, the relation between these two measures has not been sufficiently studied for localized low-effort activities. This study investigated the relation between EMG and Borg ratings, as well as the issue of gender differences during low-effort activity of forearm muscles. Nine females and nine males performed eight different hand gestures (localized low-effort activity), during which EMG signals were recorded from six forearm muscles and Borg ratings were obtained. On average, the female subjects rated the gestures as less effortful than the male subjects, and also demonstrated a higher positive correlation between the EMG and Borg ratings. Furthermore, the linear model that was fitted for predicting the Borg ratings based on gender and the combined activity of muscles provided an R-squared value of approximately 0.3.
Neuroscience, 2015
Research on motor imagery and action observation has become increasingly important in recent years particularly because of its potential benefits for movement rehabilitation and the optimization of athletic performance . Motor execution, motor imagery, and action observation have been shown to rely largely on a similar neural network in motor and motor-related cortical areas . Given that motor imagery is a covert stage of an action and its characteristics, it has been assumed that modifying the motor task in terms of, for example, effort will impact neural activity. With this background, the present study examined how different force requirements influence corticospinal excitability (CSE) and intracortical facilitation during motor imagery and action observation of a repetitive movement (dynamic force production). Participants were instructed to kinesthetically imagine or observe an abduction/adduction movement of the right index finger that differed in terms of force requirements. Trials were carried out with single-or paired-pulse transcranial magnetic stimulation. Surface electromyography was recorded from the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM). As expected, results showed a significant main effect on mean peak-to-peak motor-evoked potential (MEP) amplitudes in FDI but no differences in MEP amplitudes in ADM muscle. Participants' mean peak-to-peak MEPs increased when the force requirements (movement effort) of the imagined or observed action were increased. This reveals an impact of the imagined and observed force requirements of repetitive movements on CSE. It is concluded that this effect might be due to stronger motor neuron recruitment for motor imagery and action observation with an additional load. That would imply that the modification of motor parameters in movements such as force requirements modulates CSE. Ó 2015 The Authors. Published by Elsevier Ltd. on behalf of IBRO. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Perception of Effort Changes Following an Isometric Fatiguing Exercise of Elbow Flexors
Motor Control, 2014
The way psychometric and neurophysiological measurements of fatigue are connected is not well understood. Thus, the time course of perceived effort changes due to fatigue, as well as the peripheral and central neurophysiological changes accompanying fatigue, were evaluated. Twelve healthy participants (35 ± 9 years old) undertook 10 min intermittent isometric fatiguing exercise of elbow flexors at 50% of maximum voluntary contraction (MVC). Perceived effort ratings, using the 0-10 numeric rating scale (NRS), were recorded at midrange of MVC. Single pulse TMS of the left motor cortex and electrical stimulation over the biceps muscle was used for the assessment of voluntary activation and peripheral fatigue. The fatiguing exercise caused a 44% reduction in the MVC (p < .001) accompanied by an 18% nonsignificant reduction of the biceps MEP amplitude. The resting twitch force decreased (p < .001) while the superimposed twitches increased (p < .001) causing a decrease (19%) of the voluntary activation (p < .001). The perceived effort ratings increased by 1 point at 30%, by 2 points at 50% MVC respectively on the NRS (p < .001) and were accompanied by an increase in mean biceps EMG. A substantial role of the perceived effort in the voluntary motor control system was revealed.
Attention focus during physical effort: The mediating role of task intensity
Psychology of Sport and Exercise, 2007
O ver the past 50 years, there has been growing clinical and practical interest in the conceptualization and measurement of what we have come to know as perceived exertion. The term perceived exertion is used in the first part of this chapter because of its widespread use in the literature. Perceived effort is used in the latter part of this chapter, as it is believed to be a better term to describe an array of related perceptions, of which exertion is only one. In this chapter, we review the historical and conceptual frameworks of perceived exertion and then present the measurement tools used to operationalize perceived exertion or effort and related symptoms. We begin with a detailed background of how this field of study started and then expanded. Next we review the design and validation processes of a number of perceived exertion scales. Then we introduce theoretical frameworks and important concepts, most of which originated from the disciplines of psychophysics, physiology, and psychology. In the second part of this chapter, we discuss challenges in perceived exertion measurement. We introduce the main measurement tools currently in use and describe the application of these to research and practice. We also present a multidimensional approach to the measurement of perceived effort.