Continuous Repetition Motor Imagery Training and Physical Practice Training Exert the Growth of Fatigue and Its Effect on Performance

Abstract

Continuous repetition of motor imagery leads to mental fatigue. This study aimed to examine whether fatigue caused by motor imagery training affects improvement in performance and the change in corticospinal excitability. The participants were divided into “physical practice training” and “motor imagery training” groups, and a visuomotor task (set at 50% of maximal voluntary contraction in participants) was performed to assess the training effect on fatigue. The measurements were recorded before and after training. Corticospinal excitability at rest was measured by transcranial magnetic stimulation according to the Neurophysiological Index. Subjective mental fatigue and muscle fatigue were assessed by using the visual analog scale and by measuring the pinch force, respectively. Additionally, the error area was evaluated and calculated at pre-, mid-, and post-terms after training, using a visuomotor task. After training, muscle fatigue, subjective mental fatigue, and decreased corticospinal excitability were noted in both of the groups. Moreover, the visuomotor task decreased the error area by training; however, there was no difference in the error area between the mid- and post-terms. In conclusion, motor imagery training resulted in central fatigue by continuous repetition, which influenced the improvement in performance in the same manner as physical practice training.

A Quantitative Investigation of Mental Fatigue Elicited during Motor Imagery Practice: Selective Effects on Maximal Force Performance and Imagery Ability

“…An original finding of the present study is that the amount of effort required to complete imagined actions is mirrored by mental fatigue. This confirms the embodied nature of MI and corroborates past observations of comparable mental fatigue profiles after physical practice or MI training [15]. From a practical standpoint, this suggests that dose-response relationships guidelines for MI intervention in sports and rehabilitation should account for the demands of the tasks targeted by the MI intervention.…”

“…Overall, mental fatigue induced by MI practice appeared to have negative effects on endurance paradigms involving submaximal contractions or speed-accuracy tradeoffs [14][15][16]. By contrast, maximal isometric force performance was shown unaffected [12].…”

“…For instance, recent electroencephalography data indicated increased motor-related cortical potential and muscle activation to achieve submaximal isometric contractions of knee extensor muscles after the induction of mental fatigue through 200 MI trials [14]. Also, Nakashima et al [15] measured the effect of mental fatigue induced by physical or mental fatigue on a visuomotor control task requiring submaximal force levels. Mental fatigue was assessed before and after 200 repetitions of the task, using subjective selfreports and transcranial magnetic stimulation measures.…”

Investigating the Influence of prolonged Stroop task on mental fatigue and the consequences on corticospinal and corticocortical excitability: A pilot study

“…As the primary structure that generate the motor commands to the muscles for various physical tasks, changes in the excitability of the primary motor cortex (M1) may underlie the impaired motor performance that developed due to mental fatigue (28,29). Over the years, several studies have investigated the changes in the excitability of the M1 following prolonged or sustained cognitive exertion leading to mental fatigue (28,(30)(31)(32)(33). However, the findings of these studies are inconsistent with some studies showing an increase in corticospinal excitability (32), while others found a decrease (33) or no change (28,30,31).…”

“…Over the years, several studies have investigated the changes in the excitability of the M1 following prolonged or sustained cognitive exertion leading to mental fatigue (28,(30)(31)(32)(33). However, the findings of these studies are inconsistent with some studies showing an increase in corticospinal excitability (32), while others found a decrease (33) or no change (28,30,31). In addition to methodological differences, all the studies have primarily focused on changes in transcranial magnetic stimulation (TMS) evoked motor evoked potentials (MEPs) peak-to-peak amplitude which is an index of corticospinal excitability (CSE).…”