Effects Of Motor Imagery Research Articles

The Combination of Motor Imagery and Post-Activation Performance Enhancement is Efficient to Emphasize the Effects of Warm-Up on Sport-Specific Performance.

Motor imagery (MI) or post-activation performance enhancement (PAPE) have shown acute benefits for sports performance. The aim of the present study was to investigate the cumulative effects of MI and PAPE when combined within a warm-up routine. Ten men boxers participated in this study. They underwent four experimental sessions composed of a standardized warm-up followed by 1) maximal leg press extensions (CONTROL-PAPE), 2) mental imagery of force and sprint tasks (CONTROL-MI), 3) maximal leg press extensions followed by mental imagery of force and sprint tasks (PAPE-MI) and 4) mental imagery of force and sprint tasks followed by then maximal leg press extensions (MI-PAPE). Post-tests consisted of boxing reaction time, average and maximal boxing force, maximal handgrip strength, repeated sprint ability and the NASA-TLX fatigue questionnaire. No difference was obtained between PAPE-MI and MI-PAPE for the different measurements. Compared to CONTROL-PAPE and CONTROL-MI, both the PAPE-MI and MI-PAPE significantly enhanced boxing average force (P < 0.05) and repeated sprint ability (P < 0.01). Compared to CONTROL-PAPE, both the PAPE-MI and MI-PAPE increased boxing reaction time (P < 0.05), PAPE-MI increased the handgrip strength (P < 0.05) and MI-PAPE increased boxing maximal force (P < 0.01). Compared to CONTROL-MI, both the PAPE-MI and MI-PAPE increased boxing maximal force (P < 0.001), handgrip strength (0 < 0.01) and MI-PAPE increased boxing reaction time (P < 0.05). The NASA-TLX questionnaire was not affected by the warm-up modalities (P = 0.442). Combining PAPE-MI and MI-PAPE protocols within the warm-up produced cumulative positive effects on acute muscular performance without increasing subjective fatigue. PAPE-MI and MI-PAPE are both interesting modalities for optimizing warm-up routines.

The Effectiveness of Motor Imagery in Balance and Functional Status of Older People with Early-Stage Dementia.

Dementia involves the loss of cognitive abilities and impairs functional abilities in daily life. In motor imagery (MI) techniques, motor acts are mentally rehearsed without any overt body movements. The purpose of the randomized controlled trial was to examine the effects of MI on the motor function of older adults with dementia. Overall, 160 participants (43 men, 117 women, MMSE M = 23.20, SD = 0.15) from an Athens Day Care Center of the Alzheimer Association were randomized to (a) the MI and exercise group (experimental group) (n = 55), (b) the only exercise group (1st control group) (n = 52) and (c) the neither MI nor exercise group (2nd control group) (n = 53). The exercise session comprised 24 physiotherapy exercise sessions, lasting 45 min each, twice a week for 12 weeks. The exercises were selected from the Otago Exercise Program. Three assessments were performed: (a) one week prior to the program, (b) at one and a half months and (c) after the program. The experimental group performed a 30-minute MI with exercise program content after the end of every physiotherapy exercise session. The Multidirectional Reach Test, Five Times Sit-to-Stand Test (FTSST), Timed Up and Go test (TUG), Functional Gait Assessment (FGA) and Berg Balance Scale (BBS) were used to assess participants' balance and functional status. In the intention to treat analysis (18 participants dropped out), the 3 × 3 repeated measures ANOVA indicated statistically significant results between the three groups on (a) the TUG (F = 3.06, df (2), p = 0.04), (b) the FTSST (F = 3.00, df (2), p = 0.05), (c) the forward direction test (F = 4.14 df (2), p = 0.02), the lateral right and the lateral left direction tests (F = 3.90, df (2), p = 0.02 and F = 7.87, df (2), p = 0.00, respectively), and (d) the FGA (F = 4.35, df (2), p = 0.01). The Friedman test showed significant statistical significant differences among the three groups for BBS (X2 = 7.62, df = 2, p = 0.22), and an effect size of partial η2 coefficient for F-tests was found. Post hoc comparisons using a Bonferroni test for ANOVA and Wilcoxon test for Friedman indicated that the mean scores for the experimental group and the 1st control were significantly better than the 2rd control group in many dependent variables. The study showed a positive effect of MI on balance and the functional status of older adults with early stages of dementia with possible beneficial effects on maintaining independence and reducing physical decline.

Imagining Speeds up the Effect of Motor Imagery on Central Motor Conduction Time.

Although motor imagery (MI) has been reported to increase motor cortical excitability, its effect on central motor conduction time (CMCT), a widely used neurophysiological diagnostic method, has not been investigated. In this study, we sought to determine the effect of MI on CMCT. In this cross-sectional study, 21 healthy volunteers (11 females, 10 males) aged 24 to 67 years (mean age: 38.8 years) were recruited between April 2022 and June 2023.CMCT was calculated during MI from the abductor digiti minimi (ADM) and tibialis anterior (TA) muscles. Measurements were also performed with conventional measurement methods, such as resting and voluntary contraction, to compare the effect of MI on CMCT. The ANOVAtest revealed that the CMCT session (rest, MI, and voluntary contraction) was a significant factor (p < 0.05). In both muscles, CMCT was shorter in the imagery state than in the resting state but longer than in the voluntary contraction state (p < 0.05). Similarly, motor-evoked potential (MEP) latencies obtained during imagery were shorter for both muscles than the resting state but longer for the voluntary contraction state. The study's findings suggest that MI is a mental activity that modulates CMCT measurement.MI shows a voluntary contraction-like effect on CMCT and MEP latency, although the effect is more uncertain.

Boostering motor imagery processing to improve gait in patients with Parkinson disease and freezing of gait: A pilot study

BackgroundGiven that patients with Parkinson's Disease (PD) and Freezing of Gait (FoG) may lack the cognitive resources necessary to activate the motor imagery (MI) process, investigating how to boost MI vividness and accuracy could be a valuable therapeutic strategy in MI Practice (MIP). ObjectiveWe aim to evaluate the priming effect of visual, or auditory, or attentional stimuli in enhancing MI ability by using quantitative data on gait and turning performance. MethodsNineteen PD participants with FoG underwent four one-week sessions of MIP, with pre and post clinical assessments. Each session included MI alone or one of three booster MI tasks (Attentional, Action observation, or Auditory) before imagining and executing walking straight and performing a 180° turn. Gait and turning performances were evaluated using six inertial sensors before and after each session. ResultsOur findings showed that both MI and boosted MI induced similar improvement in gait (speed and stride length) and 180° (step number and velocity) and 360° turning (velocity, angle) parameters compared to baseline. When differences among “booster” tasks were analyzed, results showed that Auditory and Attentional boosted MI were superior to MI alone in some gait and turning parameters. At the end of the 4 sessions, MI ability measured by means of Kinesthetic and Visual Imagery Questionnaire and Gait Imagery Questionnaire and FoG symptoms were also improved. ConclusionOur preliminary results suggest that boosting MI is a feasible strategy for enhancing MI ability and addressing FoG symptoms. Auditory and Attentional conditions appear to enhance the priming effect of MI on gait and turning performance more effectively.

Neuromuscular electrical stimulation at submaximal intensity combined with motor imagery increases corticospinal excitability.

There is sparse evidence in the literature that the combination of neuromuscular electrical stimulation (NMES) and motor imagery (MI) can increase corticospinal excitability more that the application of one or the other modality alone. However, the NMES intensity usually employed was below or at motor threshold, not allowing a proper activation of the whole neuromuscular system. This questions the effect of combined MI + NMES with higher intensities, closer to those used in clinical settings. The purpose here was to assess corticospinal excitability during either MI, NMES or a combination of both at different evoked forces. Seventeen healthy participants were enrolled in one session consisting of 6 conditions targeting flexor carpi radialis muscle (FCR): rest, MI, NMES at 5% and 20% of maximal voluntary contraction (MVC) and MI and NMES performed simultaneously (MI + NMES). During each condition, corticospinal excitability was assessed by evoking MEP of FCR by using transcranial magnetic stimulation. Maximal M-wave (Mmax) was measured by using the stimulation of the median nerve. MEPs during MI were greater as compared to rest (P = 0.005). MEPs during MI were significantly lower than during MI + NMES at 5% (P = 0.02) and 20% (P = 0.001). Then, MEPs during NMES 5% was significantly lower than during MI + NMES 20% (P < 0.005). The present study showed that MI + NMES increased corticospinal excitability more than MI alone. However, corticospinal excitability was not higher as the intensity increase during MI + NMES. Therefore, MI + NMES targeting FCR may not significantly increase the corticospinal excitability between different low-submaximal contractions intensities.

Harnessing Mirror Neurons: A New Frontier in Parkinson's Disease Rehabilitation-A Scoping Review of the Literature.

Background: Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms such as tremors, rigidity, and bradykinesia. Rehabilitation utilizing mirror neurons leverages the brain's capacity for action observation (AO) and motor imagery (MI) to enhance motor function. This approach involves patients imitating movements observed in therapists or videos, aiming to improve gait, coordination, and overall quality of life. Mirror neuron activation facilitates motor learning and may decelerate disease progression, thus enhancing patient mobility and independence. Methods: This scoping review aimed to map current evidence on PD therapies employing mirror neuron-based rehabilitation. Databases searched included PubMed, PEDro, and Cochrane. The review included randomized controlled trials (RCTs) and systematic reviews that examined the effects of AO and MI in PD rehabilitation. Results: Five studies met the inclusion criteria, encompassing various rehabilitation techniques focusing on AO and MI. These studies consistently demonstrated positive outcomes, such as reduced disease severity and improved quality of life, gait, and balance in PD patients. The activation of mirror neurons through AO and MI was shown to facilitate motor learning and contribute to improved functional mobility. Conclusions: Although the included studies support the beneficial impact of AO and MI techniques in PD rehabilitation, numerous questions remain unresolved. Further research is necessary to evaluate the potential integration of these techniques into standard physiotherapy routines for PD patients. This review highlights the promise of AO and MI in enhancing motor rehabilitation for PD, suggesting the need for more comprehensive studies to validate and refine these therapeutic approaches.

Low-frequency sounds combined with motor imagery elicits a transient disruption of force performance: A path to neuromotor reprogramming?

The effectiveness of motor imagery (MI) training on sports performance is now well-documented. Recently, it has been proposed that a single session of MI combined with low frequency sound (LFS) might enhance muscle activation. However, the neural mechanisms underlying this effect remain unknown. We set up a test-retest intervention over the course of 2 consecutive days to evaluate the effect of (i) MI training (MI, n = 20), (ii) MI combined with LFS (MI + LFS, n = 20), and (iii) a control condition (CTRL, n = 20) on force torque produced across repeated maximal voluntary contractions of the quadriceps before (Pretest), after (Posttest) and at +12 h (Retention) post-intervention. We collected the integrated electromyograms of the quadriceps muscles, as well as brain electrical potentials during each experimental intervention. In the CTRL group, total force torque decreased from Pretest to Retention and from Posttest to Retention. By contrast, there was an increase between Posttest and Retention in both MI + LFS and MI groups (both ηP2 = 0.03, p < 0.05). Regression analyses further revealed a negative relationship between force performance and EEG activity in the MI + LFS group only. The data support a transient interference of LFS on cortical activity underlying the priming effects of MI practice on force performance. Findings are discussed in relation to the potential for motor reprogramming through MI combined with LFS.

The Effects of Motor Imagery on Static and Dynamic Balance and on the Fear of Re-Injury in Professional Football Players with Grade II Ankle Sprains.

Lateral ankle sprains are one of the most frequent athletic injuries in football, causing deficits in balance. Motor Imagery (MI) has been successively included in sports rehabilitation as a complementary therapeutic intervention. The aim of the present study was to explore the effects of MI on static and dynamic balance and on the fear of re-injury in professional football players with Grade II ankle sprains. Fifty-eight participants were randomly allocated into two groups: First-MI group (n = 29) and second-Placebo group (n = 29), and they each received six intervention sessions. The first MI group received MI guidance in addition to the balance training program, while the second Placebo group received only relaxation guidance. One-way ANOVA showed statistically significant results for all variables, both before and 4 weeks after the interventions for both groups. The t-test showed statistically significant differences between the two groups for static balance for the right lower extremity (t = 3.25, S (two-tailed) = 0.002, p < 0.05) and also for heart rate (final value) in all time phases. Further research is needed in order to establish MI interventions in sports trauma recovery using stronger MI treatments in combination with psychophysiological factors associated with sports rehabilitation.

Motor imagery of finger movements: Effects on cortical and muscle activities

PurposeThe purpose of the current study was to explore the immediate effect of motor imagery (MI) involving finger movement of a given limb on cortical response and muscle activity in healthy subjects. MethodsTwenty healthy right-handed adults (7 females and 13 males) with a mean + SD age of 22.05 + 6.08 years participated in the study. The beta-band event-related desynchronization (ERD) at the sensorimotor cortex and muscle activity during finger movement tasks using either the index, middle, or thumb digits on the non-dominant left hand were compared before and after an MI training session. Subjects underwent a pre-MI, MI training, and finally a post-MI session where they either performed or imagined performing a button-pushing action 50 times per session with each of the three digits. ResultsThe ERD power in the beta frequency band was lower in pre-MI compared to post-MI and was significantly different between the pre- and post-MI sessions for both the index and middle fingers, but not the thumb. A significant decrease was seen in the mean muscle activity during post-MI compared to pre-MI for all the digits except the thumb. ConclusionsThe results from the current study suggest that complex MI can result in motor learning and improvement in motor performance, thereby requiring less effort during motion.

Towards efficient motor imagery interventions after lower-limb amputation

BackgroundThe therapeutic benefits of motor imagery (MI) are now well-established in different populations of persons suffering from central nervous system impairments. However, research on similar efficacy of MI interventions after amputation remains scarce, and experimental studies were primarily designed to explore the effects of MI after upper-limb amputations.ObjectivesThe present comparative study therefore aimed to assess the effects of MI on locomotion recovery following unilateral lower-limb amputation.MethodsNineteen participants were assigned either to a MI group (n = 9) or a control group (n = 10). In addition to the course of physical therapy, they respectively performed 10 min per day of locomotor MI training or neutral cognitive exercises, five days per week. Participants’ locomotion functions were assessed through two functional tasks: 10 m walking and the Timed Up and Go Test. Force of the amputated limb and functional level score reflecting the required assistance for walking were also measured. Evaluations were scheduled at the arrival at the rehabilitation center (right after amputation), after prosthesis fitting (three weeks later), and at the end of the rehabilitation program. A retention test was also programed after 6 weeks.ResultsWhile there was no additional effect of MI on pain management, data revealed an early positive impact of MI for the 10 m walking task during the pre-prosthetic phase, and greater performance during the Timed Up and Go Test during the prosthetic phase. Also, a lower proportion of participants still needed a walking aid after MI training. Finally, the force of the amputated limb was greater at the end of rehabilitation for the MI group.ConclusionTaken together, these data support the integration of MI within the course of physical therapy in persons suffering from lower-limb amputations.

Imagética motora na reabilitação do membro superior pós AVC: uma revisão narrativa

Introduction: Considering that the brain is a highly complex and organized organ, the severity and impairment of deficits caused by a Stroke largely depend on their extent and location. These deficits are the result of the loss of neural circuits linked to sensory, motor, and cognitive functions. Various clinical studies indicate that mental training through motor imagery (MI) appears to be effective when associated with neurorehabilitation, in the recovery of upper limb function. Objective: To explore the theoretical aspects of using MI in upper limb rehabilitation post-stroke, through a narrative review. Methods: Research was conducted in bibliographic sources through the databases PubMed, EBSCOhost, CINAHL, Scopus, Web of Science, and PEDro, with the last search carried out on 30th May 2023. Results: RCT articles and systematic reviews that addressed the effects of motor imagery on upper limb function were selected for review. Conclusion: The articles analysed in this review point to a positive relationship between the effects of MI and the recovery of upper limb post-stroke, particularly when this technique is combined with Occupational Therapy and Physiotherapy, reinforcing the importance of considering the introduction of mental training with Motor Imagery in rehabilitation programs.

Effects of motor imagery and action observation on respiratory function in mild smokers: a randomized single-blind controlled pilot trial

Background: Motor imagery (MI) and action observation (AO) training can activate brain areas involved in planning, adjusting, and automating voluntary movement in a manner similar to that when these activities are being performed. Aim: The main objective of this study was to assess the effects of MI and AO training on respiratory function in mild smokers. Methods: A single-blind placebo-controlled pilot trial was designed. A total of 27 mild smokers were randomized into three groups: MI (n = 9), AO (n = 9), and sham observation (SO; n = 9) groups. The MI and AO groups performed mental training of breathing exercises while the SO group observed a landscape without a human agent. The primary outcomes were pulmonary function parameters (forced expiratory volume during the 1st s [FEV1], forced vital capacity [FVC], FEV1/FVC ratio, maximum voluntary ventilation [MVV], and peak expiratory flow [PEF]), and the secondary outcomes were maximal inspiratory/expiratory pressures (MIP/MEP) and perceived fatigue. All outcome measures were assessed at baseline and post-intervention. Results: Regarding the pulmonary function parameters, only the AO group showed significant within-group differences in FEV1 (mean differences [MD] = 0.37 L (0.17 – 0.56), P = 0.001), FVC (MD = 0.1 L (0.02 – 0.16), P = 0.008), and PEF (MD = 0.74 L/s (0.29 – 1.18), P = 0.002) with a small-to-moderate effect size. No differences were found in FEV1/FVC ratio and MVV. With regard to the maximal static pressures, only the AO group showed significant within-group differences in MEP with a small effect size (MD = 11.22 cm H2O (0.19 – 22.2), P = 0.046). Finally, both AO and MI groups showed significantly greater perceived fatigue with regard to SO group with a large effect size (P &lt; 0.05). Conclusion: AO training has a slight impact on some pulmonary function parameters, such as FEV1, FVC, or PEF, as well as on MEP when applied in isolation and in a single session. Relevance for Patients: Although it is still early to draw some solid conclusions, AO training could be used in combination with respiratory exercises to see if the effect is greater than exercises in isolation. The study of movement representation strategies on pulmonary function is a field that has been sparingly explored so far. This paper offers some interesting data to be considered for further research.

Effectiveness of motor imagery in complex regional pain syndrome: A systematic review with meta-analysis.

The purpose of this study was to determine the effects of motor imagery (MI) on pain intensity and disability in individuals with complex regional pain syndrome (CRPS). A systematic search was conducted in various electronic databases to identify all relevant studies: PubMed, CINAHL, WOS, PEDro, CENTRAL, and Scopus. Randomized controlled trials assessing the effects of MI in individuals with CRPS were included. The risk of bias was assessed with the Cochrane Risk of Bias tool, the methodological quality was evaluated using PEDro scale, and the level of evidence was reported according to the GRADE. Between-groups standardized mean differences (SMD) were calculated. Six studies were included. The meta-analysis found moderate-quality evidence that MI improves pain intensity and related disability as immediate (pain: SMD -1.07, 95% CI: -1.53 to -0.60; disability: SMD 1.05, 95% CI: 0.59 to 1.51), short-term (pain: SMD -1.28, 95% CI: -2.14 to -0.42; disability: SMD 1.37; 95% CI: 0.16 to 2.58), and long-term effects (pain: SMD -1.18; 95% CI: -1.89 to -0.46; disability: SMD 1.18; 95% CI: 0.46 to 1.89), as compared with a comparison group. The risk of bias of the trials was relatively low, but the imprecision of the results downgraded the level of evidence. Moderate-quality evidence suggests a positive effect of MI for improving pain intensity and disability immediately after and at short-term in individuals with CRPS.

Cortical Activation Patterns Determine Effectiveness of rTMS-induced Motor Imagery Decoding Enhancement in Stroke Patients.

Combination therapy with motor imagery (MI)-based brain-computer interface (BCI) and repetitive transcranial magnetic stimulation (rTMS) is a promising therapy for poststroke neurorehabilitation. However, with patients' individual differences, the clinical effects vary greatly. This study aims to explore the hypothesis that stroke patients show individualized cortical response to rTMS treatments, which determine the effectiveness of rTMS-induced MI decoding enhancement. We applied four kinds of rTMS treatments respectively to four groups of subacute stroke patients, twenty-six patients in total, and observed their EEG dynamics, MI decoding performance, and Fugl-Meyer assessment changes following 2-week neuromodulation. Four treatments consisted of ipsilesional 10 Hz rTMS, contralesional 1 Hz rTMS, ipsilesional 1 Hz rTMS, and sham stimulation. Results showed stroke patients with different neural reorganization patterns responded individually to rTMS therapy. Patients with cortical lesions mostly showed contralesional recruitment and patients without cortical lesions mostly presented ipsilesional focusing. Significant activation increases in the ipsilesional hemisphere (pre: -15.7% ∓ 8.2%, post: -17.3% ∓ 8.1%, p = 0.037) and MI decoding accuracy enhancement (pre: 76.3 ± 13.8%, post: 86.6 ± 8.2%, p = 0.037) were concurrently found in no-cortical-lesion patients with ipsilesional activation treatment. In the group of patients without cortical lesions, recovery rate in those receiving ipsilesional activation therapy (23.5 ± 10.4%) was higher than those receiving ipsilesional suppression therapy (9.9 ± 9.3%) (p = 0.041). This study reveals that tailoring neuromodulation therapy by recognizing cortical activation patterns is promising for improving effectiveness of the combination therapy with BCI and rTMS.

The effectiveness of motor imagery on physical function in individuals with stroke: A systematic review

The effectiveness of motor imagery on physical function in individuals with stroke: A systematic review

Modulation of lower limb muscle corticospinal excitability during various types of motor imagery

Motor imagery (MI) is used for rehabilitation and sports training. Previous studies focusing on the upper limb have investigated the effects of MI on corticospinal excitability in the muscles involved in the imagined movement (i.e., the agonist muscles). The present study focused on several lower-limb movements and investigated the influences of MI on corticospinal excitability in the lower limb muscles. Twelve healthy individuals (ten male and two female individuals) participated in this study. Motor-evoked potentials (MEP) from the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and soleus (SOL) muscles were elicited through transcranial magnetic stimulation (TMS) to the primary motor cortex during MI of knee extension, knee flexion, ankle dorsiflexion, and ankle plantarflexion and at rest. The results showed that the RF MEPs were significantly increased during MI in knee extension, ankle dorsiflexion, and ankle plantarflexion but not in knee flexion, compared with those at rest. The TA MEPs were significantly increased during MI in knee extension and foot dorsiflexion, while MEPs were not significantly different during MI in knee flexion and foot dorsiflexion than those at rest. For the BF and SOL muscles, there was no significant MEP modulation in either MI. These results demonstrated that corticospinal excitability of the RF and TA muscles was facilitated during MI of movements in which they are active and during MI of lower-limb movements in which they are not involved. On the contrary, corticospinal excitability of the BF and SOL muscles was not facilitated by MI of lower-limb movements. These results suggest that facilitation of corticospinal excitability depends on the muscle and the type of lower-limb MI.

Effectiveness of motor imagery on sports performance in football players: A randomised control trial.

Nowadays, the development of training programs for speed, agility and reaction time responses in football players is increasing widely. Motor imagery is a new method that uses collateral with physical training. However, there is still a scarcity of evidence concerning the addition of motor imagery protocol to routine training programs. The main objective was to compare speed, agility and reaction time after motor imagery training in university athletes and amateur athletes who received and did not receive motor imagery training for 2 weeks. Participants were divided into 4 subgroups as follows: university athlete group with motor imagery training and control group, amateur athlete group with motor imagery training and control group. This study collected the training effects of speed, agility and reaction time. The Wilcoxon signed-rank test and the Mann-Whitney U test were selected to analyse the differences within and between groups, respectively. The result presented positive changes in all variables after training sessions for 2 weeks in all groups. Speed at 20 m, agility, and reaction time were found to be significantly different after motor imagery training in both university athletes and amateur athletes. This finding demonstrated that the addition of the motor imagery training along with routine physical training promotes physical performance in athletes at all experience levels. In further studies, the retention effect after practice should be considered.

Inter-task transfer of force gains is facilitated by motor imagery.

There is compelling evidence that motor imagery (MI) contributes to improve muscle strength. While strong effects have been observed for finger muscles, only few experiments with moderate benefits were conducted within applied settings targeting large upper or lower limb muscles. The aim of the present study was therefore to extend the investigation of embedded MI practice designed to improve maximal voluntary strength on a multi-joint dynamic exercise involving the lower limbs. Additionally, we tested whether targeting the content of MI on another movement than that physically performed and involving the same body parts might promote inter-task transfer of strength gains. A total of 75 participants were randomly assigned into three groups who underwent a physical training on back squat. During inter-trial recovery periods, a first MI group (n = 25) mentally rehearsed the back squat, while a second MI group (n = 25) performed MI of a different movement involving the lower limbs (deadlift). Participants from the control group (n = 25) completed a neutral cognitive task during equivalent time. Strength and power gains were assessed ecologically using a velocity transducer device at 4 different time periods. Data first revealed that participants who engaged in MI of the back squat improved their back squat performance (p < 0.03 and p < 0.01, respectively), more than the control group (p < 0.05), hence supporting the positive effects of MI on strength. Data further supported the inter-task transfer of strength gains when MI targeted a movement that was not physically trained (p = 0.05). These findings provide experimental support for the use of MI during physical training sessions to improve and transfer force development.

Effects of neurofeedback on standing postural control task with combined imagined and executed movements.

Motor imagery (MI) is a method of imagining movement without actual movement, and its use in combination with motor execution (ME) enhances the effects of motor learning. Neurofeedback (NFB) is another method that promotes the effects of MI. This study aimed to investigate the effects of NFB on combined MI and ME (MIME) training in a standing postural control task. Sixteen participants were randomly divided into MIME and MIME + NFB groups and performed 10 trials of a postural control task on an unstable board, with nine trials of MI in between. Electroencephalogram was assessed during MI, and the MIME + NFB group received neurofeedback on the degree of MI via auditory stimulation. A postural control task using an unstable board was performed before and after the MIME task, during which postural instability was evaluated. Postural instability was reduced after the MIME task in both groups. In addition, the root mean square, which indicates the sway of the unstable board, was significantly reduced in the MIME + NFB group compared to that in the MIME group. Our results indicate that MIME training is effective for motor learning of standing postural control. Furthermore, when MI and ME are combined, the feedback on the degree of MI enhances the learning effect.

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

In the present study, we examined the development of mental fatigue during the kinesthetic motor imagery (MI) of isometric force contractions performed with the dominant upper limb. Participants (n = 24) underwent four blocks of 20 MI trials of isometric contractions at 20% of the maximal voluntary contraction threshold (20% MVCMI) and 20 MI trials of maximal isometric contractions (100% MVCMI). Mental fatigue was assessed after each block using a visual analogue scale (VAS). We assessed maximal isometric force before, during and after MI sessions. We also assessed MI ability from self-report ratings and skin conductance recordings. Results showed a logarithmic pattern of increase in mental fatigue over the course of MI, which was superior during 100% MVCMI. Unexpectedly, maximal force improved during 100% MVCMI between the 1st and 2nd evaluations but remained unchanged during 20% MVCMI. MI ease and vividness improved during 100% MVCMI, with a positive association between phasic skin conductance and VAS mental fatigue scores. Conversely, subjective measures revealed decreased MI ability during 20% MVCMI. Mental fatigue did not hamper the priming effects of MI on maximal force performance, nor MI's ability for tasks involving high physical demands. By contrast, mental fatigue impaired MI vividness and elicited boredom effects in the case of motor tasks with low physical demands.