Effects and Dose-Response Relationships of Motor Imagery Practice on Strength Development in Healthy Adult Populations: a Systematic Review and Meta-analysis

[Postoperative rehabilitation after knee arthroplasty]

BACKGROUND

Postoperative rehabilitation after knee arthroplasty plays a decisive role in restoring the function and mobility of the affected joint. However, there is still disagreement regarding the setting, structure and content of rehabilitation after knee arthroplasty, and the evidence on the individual measures is largely unclear. The aim of this article is to provide an evidence-based overview of the current status of rehabilitation after knee arthroplasty and to critically discuss the points that are still unclear. In view of the increasing prevalence of knee osteoarthritis and the rising number of knee endoprosthesis implantations, the optimization and scientific processing of postoperative rehabilitation is more important than ever in order to be able to offer scientifically sound, practice-oriented and cost-effective rehabilitation measures in the future.

MATERIAL AND METHODS

This review is based on a systematic literature search in Medline, Cochrane Library and Web of Science databases on the topic of postoperative rehabilitation after knee arthroplasty.

RESULTS

Regarding specific treatment components, duration and frequency after knee arthroplasty, the evidence is unclear. Passive therapies should only be used supportive to active interventions. Educational programmes before and after knee arthroplasty can play a crucial role in outcome and patient satisfaction. Regular strength training should always be combined with centrally oriented components, such as motor imagery, to achieve better movement visualization and central anchoring. There is still a frequent lack of scientific evidence regarding individual therapeutic measures, their intensity, frequency, duration, exercise selection and their specific implementation in rehabilitation after knee arthroplasty. In the future, digital diagnostic and training tools will become established in both inpatient and outpatient therapy, supporting the urgently needed data collection for the scientific analysis of individual therapeutic measures.

Developmental trajectories of motor imagery in relation to physical fitness in children aged 7 to 14 years: A 1-year follow-up study

Motor imagery (MI) is fundamentally linked to the motor system. It improves motor learning and optimizes motor actions without physical execution, highlighting its unique role in rehabilitation programs and motor performance. Understanding the developmental trajectories of MI and the factors influencing its variability across ages could enable more effective, age-specific strategies for pediatric rehabilitation. This study assessed 65 children aged 7 to 14 years at two time points 1 year apart. MI ability was assessed using the Movement Imagery Questionnaire for Children, and physical fitness was evaluated using the SLOfit testing battery. Among the three perspectives assessed; internal visual imagery (IVI), external visual imagery (EVI), and kinesthetic imagery (KI), KI was unique in not correlating with age at both time points. The development of MI perspectives varied between athletes and non-athletes, with non-athletes showing a decline in IVI compared with athletes. This differential was further evidenced by significant differences in KI between the groups at the second assessment, with a similar trend observed at the first assessment. Of the physical fitness tests, only the 600-m run correlated consistently with KI at both assessments. Our findings suggest that regular participation in sports significantly affects KI performance, highlighting the importance of sports participation for the development of MI abilities in children. Future research should examine additional assessment points in different age groups and sport experience to better understand the development of MI and its potential implications for pediatric rehabilitation.

Motor imagery priming improves activity and impairment outcomes in people after stroke but the effects of other types of priming are unclear: a systematic review

QUESTION

In stroke rehabilitation, what is the effect of adding non-stimulation-based priming prior to task-specific practice on activity and motor impairment outcomes compared with task-specific practice alone?

DESIGN

Systematic review with meta-analysis.

PARTICIPANTS

Adult stroke survivors.

INTERVENTION

The experimental groups completed a non-stimulation priming intervention prior to task-specific practice. The priming interventions were: motor imagery; action observation; combined motor imagery and action observation; mirror therapy; movement-based priming; and aerobic exercise-based priming. The control groups completed task-specific practice alone.

OUTCOME MEASURES

Upper and lower limb activity and motor impairment.

RESULTS

Twenty-four trials involving 803 participants were included in this systematic review. Twenty trials were included in the meta-analyses of activity outcomes and 11 trials in the meta-analyses of impairment outcomes. Four trials examined the effect of motor imagery priming prior to task-specific practice on activity outcomes (SMD 0.48, 95% CI 0.13 to 0.82). Three trials examined the effect of motor imagery priming prior to task-specific practice on motor impairment outcomes (SMD 0.51, 95% CI 0.12 to 0.89). Nine trials examined the effect of action observation priming prior to task-specific practice on activity outcomes (SMD 0.18, 95% CI -0.06 to 0.41). Two trials examined the effect of movement-based priming prior to task-specific practice on activity outcomes (SMD -0.11, 95% CI -0.64 to 0.42). Three trials examined the effect of aerobic exercise priming prior to task-specific practice on activity outcomes (SMD 0.30, 95% CI -0.19 to 0.80). The quality of the evidence was low to moderate.

CONCLUSION

In stroke rehabilitation, motor imagery priming implemented prior to task-specific training has a very small to large effect on activity and motor impairment outcomes. Action observation priming implemented prior to task-specific training has a negligible to small effect on activity outcomes. Movement-based and aerobic exercise-based priming do not have any clear effect on outcomes.

REGISTRATION

CRD42020093519.

Why motor imagery is not really motoric: towards a re-conceptualization in terms of effect-based action control

Overt and imagined action seem inextricably linked. Both have similar timing, activate shared brain circuits, and motor imagery influences overt action and vice versa. Motor imagery is, therefore, often assumed to recruit the same motor processes that govern action execution, and which allow one to play through or simulate actions offline. Here, we advance a very different conceptualization. Accordingly, the links between imagery and overt action do not arise because action imagery is intrinsically motoric, but because action planning is intrinsically imaginistic and occurs in terms of the perceptual effects one want to achieve. Seen like this, the term 'motor imagery' is a misnomer of what is more appropriately portrayed as 'effect imagery'. In this article, we review the long-standing arguments for effect-based accounts of action, which are often ignored in motor imagery research. We show that such views provide a straightforward account of motor imagery. We review the evidence for imagery-execution overlaps through this new lens and argue that they indeed emerge because every action we execute is planned, initiated and controlled through an imagery-like process. We highlight findings that this new view can now explain and point out open questions.

Exploring the Dose-Response Relationship Between Estimated Resistance Training Proximity to Failure, Strength Gain, and Muscle Hypertrophy: A Series of Meta-Regressions

BACKGROUND

The proximity to failure in which sets are terminated has gained attention in the scientific literature as a potentially key resistance training variable. Multiple meta-analyses have directly (i.e., failure versus not to failure) or indirectly (e.g., velocity loss, alternative set structures) evaluated the effect of proximity to failure on strength and muscle hypertrophy outcomes categorically; however, the dose-response effects of proximity to failure have not been analyzed collectively in a continuous manner.

OBJECTIVE

To meta-analyze the aforementioned areas of relevant research, proximity to failure was quantified as the number of repetitions in reserve (RIR). Importantly, the RIR associated with each effect in the analysis was estimated on the basis of the available descriptions of the training interventions in each study. Data were extracted and a series of exploratory multilevel meta-regressions were performed for outcomes related to both strength and muscle hypertrophy. A range of sensitivity analyses were also performed. All models were adjusted for the effects of load, method of volume equating, duration of intervention, and training status.

RESULTS

The best fit models for both strength and muscle hypertrophy outcomes demonstrated modest quality of overall fit. In all of the best-fit models for strength, the confidence intervals of the marginal slopes for estimated RIR contained a null point estimate, indicating a negligible relationship with strength gains. However, in all of the best-fit models for muscle hypertrophy, the marginal slopes for estimated RIR were negative and their confidence intervals did not contain a null point estimate, indicating that changes in muscle size increased as sets were terminated closer to failure.

CONCLUSIONS

The dose-response relationship between proximity to failure and strength gain appears to differ from the relationship with muscle hypertrophy, with only the latter being meaningfully influenced by RIR. Strength gains were similar across a wide range of RIR, while muscle hypertrophy improves as sets are terminated closer to failure. Considering the RIR estimation procedures used, however, the exact relationship between RIR and muscle hypertrophy and strength remains unclear. Researchers and practitioners should be aware that optimal proximity to failure may differ between strength and muscle hypertrophy outcomes, but caution is warranted when interpreting the present analysis due to its exploratory nature. Future studies deliberately designed to explore the continuous nature of the dose-response effects of proximity to failure in large samples should be considered.

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.

Illness acceptance and its relationship to health-behaviors among patients with type 2 diabetes: A mediating role of self-hardiness

OBJECTIVES

The current study aims to assess the level of acceptance of their illness in patients diagnosed with type 2 diabetes mellitus, determine whether the self-hardiness of patients with type 2 diabetes mellitus can serve as a predictive factor for their illness acceptance and health-behaviors, and Explore variations in illness acceptance, health-behaviors, and self-hardiness in relation to socio-demographic factors among patients with type 2 diabetes mellitus.

METHODOLOGY

A descriptive correlational study was carried out at Al-Rifia Teaching Hospital, and and Imam Al-Qiam Health Center. the study was started from 15th October, 2023 to 3th March, 2024. Purposive sample (non-probability) of 200 patients with type 2 diabetes (male and female). by the used of questionnaire and interviews techniques, data are collected from those who diagnosed with diabetes mellitus. the study instrument consisted of four parts: part one the sociodemographic sheet, part two concerned illness acceptance which composed of 22 items, part three health behaviors which composed of 22 items, and part four concerned self-hardiness which composed of 25 items.

RESULTS

The study results revealed that the who participated in this study their age 55-64 years old and constituted 64 (32.0%), more than half of participants were male patients with type 2 diabetes mellitus 109 (54.5%), where revealed (79.5%) exhibited that the neutral acceptance level as described by mean score (±SD) = 2.075, health-behaviors among patients with type 2 diabetes, findings illustrated that the (51.0%) of patients with type 2 diabetes mellitus exhibited that they follow good health-behaviors level, and good Self-Hardiness among Patients with Type 2 diabetes, in addition, there is a high significant relationship between illness acceptance, health behaviors and patients self-hardness at p-value (< 0.005).

RECOMMENDATIONS

should support people with educational initiatives and assist them in accepting their sickness and taking an active role in managing it, Psychological support to resolve disease-related problems, cope with difficulties and develop positive attitudes towards the disease.

A 6-minute protocol, combining mental imagery practices and breathing exercises, promotes hand-grip strength in firefighters: a series of "N-of-1" trials

BACKGROUND

To carry out their victim rescue and fire-fighting missions, firefighters perform high levels of physical exertion and among them strenuous muscular activity. A specific mental preparation protocol that could induce better strength performance throughout their 24-hour schedule is a major issue for firefighters.

OBJECTIVE

This case report aims to examine whether a 6-minute Intervention combining mental imagery practices and breathing exercises, specifically designed to be used while travelling between the fire station and the mission site, would be able to promote maximum strength performance.

METHODS

A series of three Single Case Experimental Designs (SCED) was conducted in single blind design to investigate the effects of repeated challenge-withdrawals between the Intervention and the Baseline on the maximum voluntary isometric contraction (MVIC) strength of the hand-grip.

RESULTS

Data analyses revealed that 62.5% to 100% of the hand-grip strength values during the Intervention periods were greater than or equal to the maximum data point recorded in the Baseline periods. The effect sizes of these highlighted increases of the hand-grip strength performance revealed by the percentage of non-overlapping data (PND) were 75% i.e., moderately effective on average.

CONCLUSIONS

Such a "psyching-up" practice before an upcoming muscular activity can promote muscular strength in firefighters. These results have led French firefighter departments to integrate the teaching of these practices into the initial instruction of firefighters, and remains to be confirmed by a randomised control trial.

Inequivalent and uncorrelated response priming in motor imagery and execution

Introduction

Theoretical considerations on motor imagery and motor execution have long been dominated by the functional equivalence view. Previous empirical works comparing these two modes of actions, however, have largely relied on subjective judgments on the imagery process, which may be exposed to various biases. The current study aims to re-examine the commonality and distinguishable aspects of motor imagery and execution via a response repetition paradigm. This framework aims to offer an alternative approach devoid of self-reporting, opening the opportunity for less subjective evaluation of the disparities and correlations between motor imagery and motor execution.

Methods

Participants performed manual speeded-choice on prime-probe pairs in each trial under three conditions distinguished by the modes of response on the prime: mere observation (Perceptual), imagining response (Imagery), and actual responses (Execution). Responses to the following probe were all actual execution of button press. While Experiment 1 compared the basic repetition effects in the three prime conditions, Experiment 2 extended the prime duration to enhance the quality of MI and monitored electromyography (EMG) for excluding prime imagery with muscle activities to enhance specificity of the underlying mechanism.

Results

In Experiment 1, there was no significant repetition effect after mere observation. However, significant repetition effects were observed in both imagery and execution conditions, respectively, which were also significantly correlated. In Experiment 2, trials with excessive EMG activities were excluded before further statistical analysis. A consistent repetition effect pattern in both Imagery and Execution but not the Perception condition. Now the correlation between Imagery and Execution conditions were not significant.

Conclusion

Findings from the current study provide a novel application of a classical paradigm, aiming to minimize the subjectivity inherent in imagery assessments while examining the relationship between motor imagery and motor execution. By highlighting differences and the absence of correlation in repetition effects, the study challenges the functional equivalence hypothesis of imagery and execution. Motor representations of imagery and execution, when measured without subjective judgments, appear to be more distinguishable than traditionally thought. Future studies may examine the neural underpinnings of the response repetition paradigm to further elucidating the common and separable aspects of these two modes of action.

Effects of digital-based interventions on muscular strength in adults: a systematic review, meta-analysis and meta-regression of randomized controlled trials with quality of evidence assessment

BACKGROUND

In the last three decades, both medical and sports science professionals have recognized the considerable potential of digital-based interventions (DBI) to enhance the health-related outcomes of their practitioners.

OBJECTIVES

This study aimed to investigate the effectiveness and potential moderators of DBI on measures of muscular strength.

METHODS

Six databases (PubMed/MEDLINE, Web of Science, SportDiscus, Embase, Cochrane Register of Controlled Trials and Google Scholar) were searched for eligible studies up to June 2022. The GRADE, PEDRO, and TIDieR checklists were used to assess the quality of evidence, methodology, and completeness of intervention descriptions, respectively.

RESULTS

A total of 56 studies were included in the meta-analysis (n = 2346), and participants were classified as healthy (n = 918), stroke survivors (n = 572), diagnosed with other neurological disorders (n = 683), and frail (n = 173). The DBI showed a small effect (standardized mean difference [SMD] = 0.28, 95% CI 0.21 to 0.31; p < 0.001) on strength, regardless of the type of intervention, control group, or tested body part. More specifically, while splitting the studies into different subgroups, a meta-analysis of 19 studies (n = 918) showed a small effect (SMD = 0.38, 95% CI 0.12 to 0.63; p = 0.003) on strength in the asymptomatic population. Similarly, small but positive effects of DBI were observed for stroke survivors (SMD = 0.34, 95% CI 0.13 to 0.56; p = 0.002), patients diagnosed with other neurological disorders (SMD = 0.17, 95% CI 0.03 to 0.32; p = 0.021), and the frail population (SMD = 0.25, 95% CI 0.0 to 0.5; p = 0.051). Sub-group analysis and meta-regression revealed that neither variable modified the effects of the DBI on measures of strength.

CONCLUSIONS

Overall, DBI may serve as an effective method to improve measures of strength in adults, regardless of their health status as well as the type of digital device, the presence of human-computer interaction, and the age of participants. In addition, the DBI was found to be more effective than traditional training or rehabilitation methods.KEY MESSAGESDigital-based intervention (DBI) is effective in improving measures of muscular strength in adults regardless of participants' health statusDBIs were equally effective for strength improvements in lower and upper limbsAlthough, DBIs were found to be effective in improving muscular strength, most studies did not follow strength training guidelines when prescribing the interventions.

Effects of Bed Rest on Physical Performance in Athletes: A Systematic and Narrative Review

BACKGROUND

Athletes can face scenarios in which they are confined to bed rest (e.g., due to injury or illness). Existing research in otherwise healthy individuals indicates that those entering bed rest with the greatest physical performance level might experience the greatest performance decrements, which indirectly suggests that athletes might be more susceptible to the detrimental consequences of bed rest than general populations. Therefore, a comprehensive understanding of the effects of bed rest might help guide the medical care of athletes during and following bed rest.

OBJECTIVE

This systematic and narrative review aimed to (1) establish the evidence for the effects of bed rest on physical performance in athletes; (2) discuss potential countermeasures to offset these negative consequences; and (3) identify the time-course of recovery following bed rest to guide return-to-sport rehabilitation.

METHODS

This review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Four databases were searched (SPORTDiscus, Web of Science, Scopus, and MEDLINE/PubMed) in October of 2022, and studies were included if they were peer-reviewed investigations, written in English, and investigated the effects of horizontal bed rest on changes in physical capacities and qualities in athletes (defined as Tier 3-5 participants). The reporting quality of the research was assessed using a modified version of the Downs & Black checklist. Furthermore, findings from studies that involved participants in Tiers 1-2 were presented and synthesized using a narrative approach.

RESULTS

Our systematic review of the literature using a rigorous criterion of 'athletes' revealed zero scientific publications. Nevertheless, as a by-product of our search, seven studies were identified that involved apparently healthy individuals who performed specific exercise training prior to bed rest.

CONCLUSIONS

Based on the limited evidence from studies involving non-athletes who were otherwise healthy prior to bed rest, we generally conclude that (1) bed rest rapidly (within 3 days) decreases upright endurance exercise performance, likely due to a rapid loss in plasma volume; whereas strength is reduced within 5 days, likely due to neural factors as well as muscle atrophy; (2) fluid/salt supplementation may be an effective countermeasure to protect against decrements in endurance performance during bed rest; while a broader array of potentially effective countermeasures exists, the efficacy of these countermeasures for previously exercise-trained individuals requires further study; and (3) athletes likely require at least 2-4 weeks of progressive rehabilitation following bed rest of ≤ 28 days, although the timeline of recovery might need to be extended depending on the underlying reason for bed rest (e.g., injury or illness). Despite these general conclusions from studies involving non-athletes, our primary conclusion is that substantial effort and research is still required to quantify the effects of bed rest on physical performance, identify effective countermeasures, and provide return-to-sport timelines in bona fide athletes.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

Registration ID: osf.io/d3aew; Date: October 24, 2022.

The effect of movement representation techniques on ankle function and performance in persons with or without a lateral ankle sprain: a systematic review and meta-analysis

BACKGROUND

Lateral ankle sprains are highly prevalent and result in tissue damage, impairments of muscle strength, instability, and muscle activation. Up to 74% will experience ongoing symptoms after a lateral ankle sprain. In healthy subjects, motor imagery might induce neural changes in the somatosensory and motor areas of the brain, yielding favourable enhancements in muscular force. However, during motor imagery, difficulties in building a motor image, no somatosensory feedback, and the absence of structural changes at the level of the muscle might explain the differences found between motor imagery and physical practice. In rehabilitation, motor imagery might be supportive in rebuilding motor networks or creating new networks to restore impairments in muscle activation and movement patterns. This systematic review was undertaken to summarize the current body of evidence about the effect on motor imagery, or action observation, on lower leg strength, muscle performance, ankle range of motion, balance, and edema in persons with, and without, a lateral ankle sprain compared to usual care, a placebo intervention, or no intervention.

METHODS

A systematic review with meta-analysis of randomized controlled trials was conducted in healthy participants and participants with a lateral ankle sprain. Motor imagery or action observation in isolation, or in combination with usual care were compared to a placebo intervention, or no intervention. An electronic search of MEDLINE, EMBASE, Cinahl, Psychinfo, Sportdiscus, Web of Science, Cochrane and Google Scholar was conducted, and articles published up to 7th June 2023 were included. Two reviewers individually screened titles and abstracts for relevancy using the inclusion criteria. Variables related to muscle strength, muscle function, range of motion, balance, return to sports tests, or questionnaires on self-reported function or activities were extracted. A risk of bias assessment was done using the Cochrane Risk-of-Bias tool II by two reviewers. Meta-analysis using a random effects model was performed when two or more studies reported the same outcome measures. The Standardized Mean Difference (SMD) was calculated over the change from baseline scores. Review manager 5.4 was used to perform analysis of subgroup differences and test for statistically significant differences. Confidence intervals were visually checked for overlap between subgroups.

RESULTS

Nine studies, six examining healthy participants and three examining participants with an acute lateral ankle sprain, were included. All studies were rated with moderate to high risk of bias overall. Quality of the motor imagery interventions differed largely between studies. Meta-analysis showed a large and significant effect of motor imagery on lower leg strength (SMD 1.47, 95% CI 0.44 to 2.50); however, the evidence was downgraded to very low certainty due to substantial heterogeneity (I2 = 73%), limitations in the studies (some concerns in risk of bias in all studies), and imprecision (n =  < 300). Evidence showed no association with ankle range of motion (SMD 0.25, 95% CI -0.43 to 0.93), edema (SMD -1.11, 95% CI -1.60 to 3.81), the anterior reach direction of the Star Excursion Balance Test (SEBT) (SMD 0.73, 95% CI -0.62 to 2.08), the posterolateral direction (SMD 0.32, 95% CI -0.94 to 1.57), and the posteromedial direction (SMD 0.52, 95% CI -0.07 to 1.10). The certainty of evidence for the different comparisons was very low.

CONCLUSIONS

There is a low certainty, significant, positive effect for motor imagery being able to improve lower leg muscle strength in healthy participants. The effect on balance, range of motion and edema was uncertain and of very low certainty.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021243258.

Influence of motor imagery training on hip abductor muscle strength and bilateral transfer effect

Motor imagery training could be an important treatment of reduced muscle function in patients and injured athletes. In this study, we investigated the efficacy of imagery training on maximal force production in a larger muscle group (hip abductors) and potential bilateral transfer effects. Healthy participants (n = 77) took part in two experimental studies using two imagery protocols (∼30 min/day, 5 days/week for 2 weeks) compared either with no practice (study 1), or with isometric exercise training (study 2). Maximal hip abduction isometric torque, electromyography amplitudes (trained and untrained limbs), handgrip strength, right shoulder abduction (strength and electromyography), and imagery capability were measured before and after the intervention. Post intervention, motor imagery groups of both studies exhibited significant increase in hip abductors strength (∼8%, trained side) and improved imagery capability. Further results showed that imagery training induced bilateral transfer effects on muscle strength and electromyography amplitude of hip abductors. Motor imagery training was effective in creating functional improvements in limb muscles of trained and untrained sides.

Environmental enrichment through virtual reality as multisensory stimulation to mitigate the negative effects of prolonged bed rest

Prolonged bed rest causes a multitude of deleterious physiological changes in the human body that require interventions even during immobilization to prevent or minimize these negative effects. In addition to other interventions such as physical and nutritional therapy, non-physical interventions such as cognitive training, motor imagery, and action observation have demonstrated efficacy in mitigating or improving not only cognitive but also motor outcomes in bedridden patients. Recent technological advances have opened new opportunities to implement such non-physical interventions in semi- or fully-immersive environments to enable the development of bed rest countermeasures. Extended Reality (XR), which covers augmented reality (AR), mixed reality (MR), and virtual reality (VR), can enhance the training process by further engaging the kinesthetic, visual, and auditory senses. XR-based enriched environments offer a promising research avenue to investigate the effects of multisensory stimulation on motor rehabilitation and to counteract dysfunctional brain mechanisms that occur during prolonged bed rest. This review discussed the use of enriched environment applications in bedridden patients as a promising tool to improve patient rehabilitation outcomes and suggested their integration into existing treatment protocols to improve patient care. Finally, the neurobiological mechanisms associated with the positive cognitive and motor effects of an enriched environment are highlighted.

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

Introduction

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.

Methods

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.

Results

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).

Discussion

These findings provide experimental support for the use of MI during physical training sessions to improve and transfer force development.

Bilateral transfer of motor performance as a function of motor imagery training: a systematic review and meta-analysis

Objective

The objective of this review was to evaluate the efficacy of mental imagery training (MIT) in promoting bilateral transfer (BT) of motor performance for healthy subjects.

Data sources

We searched 6 online-databases (Jul-Dec 2022) using terms: "mental practice," "motor imagery training," "motor imagery practice," "mental training," "movement imagery," "cognitive training," "bilateral transfer," "interlimb transfer," "cross education," "motor learning," "strength," "force" and "motor performance."

Study selection and data extraction

We selected randomized-controlled studies that examined the effect of MIT on BT. Two reviewers independently determined if each study met the inclusion criteria for the review. Disagreements were resolved through discussion and, if necessary, by a third reviewer. A total of 9 articles out of 728 initially identified studies were chosen for the meta-analysis.

Data synthesis

The meta-analysis included 14 studies for the comparison between MIT and no-exercise control (CTR) and 15 studies for the comparison between MIT and physical training (PT).

Results

MIT showed significant benefit in inducing BT compared to CTR (ES = 0.78, 95% CI = 0.57-0.98). The effect of MIT on BT was similar to that of PT (ES = -0.02, 95% CI = -0.15-0.17). Subgroup analyses showed that internal MIT (IMIT) was more effective (ES = 2.17, 95% CI = 1.57-2.76) than external MIT (EMIT) (ES = 0.95, 95% CI = 0.74-1.17), and mixed-task (ES = 1.68, 95% CI = 1.26-2.11) was more effective than mirror-task (ES = 0.46, 95% CI = 0.14-0.78) and normal-task (ES = 0.56, 95% CI = 0.23-0.90). No significant difference was found between transfer from dominant limb (DL) to non-dominant limb (NDL) (ES = 0.67, 95% CI = 0.37-0.97) and NDL to DL (ES = 0.87, 95% CI = 0.59-1.15).

Conclusion

This review concludes that MIT can serve as a valuable alternative or supplement to PT in facilitating BT effects. Notably, IMIT is preferable to EMIT, and interventions incorporating tasks that have access to both intrinsic and extrinsic coordinates (mixed-task) are preferred over those that involve only one of the two coordinates (mirror-task or normal-task). These findings have implications for rehabilitation of patients such as stroke survivors.

Maximizing Strength: The Stimuli and Mediators of Strength Gains and Their Application to Training and Rehabilitation

ABSTRACT

Spiering, BA, Clark, BC, Schoenfeld, BJ, Foulis, SA, and Pasiakos, SM. Maximizing strength: the stimuli and mediators of strength gains and their application to training and rehabilitation. J Strength Cond Res 37(4): 919-929, 2023-Traditional heavy resistance exercise (RE) training increases maximal strength, a valuable adaptation in many situations. That stated, some populations seek new opportunities for pushing the upper limits of strength gains (e.g., athletes and military personnel). Alternatively, other populations strive to increase or maintain strength but cannot perform heavy RE (e.g., during at-home exercise, during deployment, or after injury or illness). Therefore, the purpose of this narrative review is to (a) identify the known stimuli that trigger gains in strength; (b) identify the known factors that mediate the long-term effectiveness of these stimuli; (c) discuss (and in some cases, speculate on) potential opportunities for maximizing strength gains beyond current limits; and (d) discuss practical applications for increasing or maintaining strength when traditional heavy RE cannot be performed. First, by conceptually deconstructing traditional heavy RE, we identify that strength gains are stimulated through a sequence of events, namely: giving maximal mental effort, leading to maximal neural activation of muscle to produce forceful contractions, involving lifting and lowering movements, training through a full range of motion, and (potentially) inducing muscular metabolic stress. Second, we identify factors that mediate the long-term effectiveness of these RE stimuli, namely: optimizing the dose of RE within a session, beginning each set of RE in a minimally fatigued state, optimizing recovery between training sessions, and (potentially) periodizing the training stimulus over time. Equipped with these insights, we identify potential opportunities for further maximizing strength gains. Finally, we identify opportunities for increasing or maintaining strength when traditional heavy RE cannot be performed.

Elderly may benefit more from motor imagery training in gaining muscle strength than young adults: A systematic review and meta-analysis

Objective

The current review was aimed to determine the effectiveness of mental imagery training (MIT) on the enhancement of maximum voluntary muscle contraction (MVC) force for healthy young and old adults.

Data sources

Six electronic databases were searched from July 2021 to March 2022. Search terms included: "motor imagery training," "motor imagery practice," "mental practice," "mental training," "movement imagery," "cognitive training," "strength," "force," "muscle strength," "performance," "enhancement," "improvement," "development," and "healthy adults."

Study selection and data extraction

Randomized controlled trials of MIT in enhancing muscle strength with healthy adults were selected. The decision on whether a study met the inclusion criteria of the review was made by two reviewers independently. Any disagreements between the two reviewers were first resolved by discussion between the two reviewers. If consensus could not be reached, then it would be arbitrated by a third reviewer.

Data synthesis

Twenty-five studies including both internal MIT and external MIT were included in meta-analysis for determining the efficacy of MIT on enhancing muscle strength and 22 internal MIT were used for subgroup analysis for examining dose-response relationship of MIT on MVC.

Results

MIT demonstrated significant benefit on enhancing muscle strength when compared with no exercise, Effect Size (ES), 1.10, 95% confidence interval (CI), 0.89-1.30, favoring MIT, but was inferior to physical training (PT), ES, 0.38, 95% CI, 0.15-0.62, favoring PT. Subgroup analysis demonstrated that MIT was more effective for older adults (ES, 2.17, 95% CI, 1.57-2.76) than young adults (ES, 0.95, 95% CI, 0.74-1.17), p = 0.0002, and for small finger muscles (ES, 1.64, 95% CI, 1.06-2.22) than large upper extremity muscles (ES, 0.86, 95% CI, 0.56-1.16), p = 0.02. No significant difference was found in the comparison of small finger muscles and large lower extremity muscles, p = 0.19 although the ES of the former (ES, 1.64, 95% CI, 1.06-2.22) was greater than that of the later (ES, 1.20, 95%, 0.88-1.52).

Conclusion

This review demonstrates that MIT has better estimated effects on enhancing MVC force compared to no exercise, but is inferior to PT. The combination of MIT and PT is equivalent to PT alone in enhancing muscle strength. The subgroup group analysis further suggests that older adults and small finger muscles may benefit more from MIT than young adults and larger muscles.

Effects of motor imagery training on skeletal muscle contractile properties in sports science students

Background

Studies on motor imagery (MI) practice based on different designs and training protocols have reported changes in maximal voluntary contraction (MVC) strength. However, to date, there is a lack of information on the effects of MI training on contractile properties of the trained muscle.

Methods

Forty-five physically active sport science students (21 female) were investigated who trained three times per week over a 4-week period in one of three groups: An MI group conducted MI practice of maximal isometric contraction of the biceps brachii; a physical exercise (PE) group physically practiced maximal isometric contractions of the biceps brachii in a biceps curling machine; and a visual imagery (VI) group performed VI training of a landscape. A MVC test of the arm flexors was performed in a biceps curling machine before and after 4 weeks of training. The muscular properties of the biceps brachii were also tested with tensiomyography measurements (TMG).

Results

Results showed an interaction effect between time and group for MVC (p = 0.027, η ² = 0.17), with a higher MVC value in the PE group (Δ5.9%) compared to the VI group (Δ -1.3%) (p = 0.013). MVC did not change significantly in the MI group (Δ2.1%). Analysis of muscle contractility via TMG did not show any interaction effects neither for maximal radial displacement (p = 0.394, η ² = 0.05), delay time (p = 0.79, η ² = 0.01) nor contraction velocity (p = 0.71, η ² = 0.02).

Conclusion

In spite of MVC-related changes in the PE group due to the interventions, TMG measurements were not sensitive enough to detect concomitant neuronal changes related to contractile properties.

Corticomotor Plasticity Underlying Priming Effects of Motor Imagery on Force Performance

The neurophysiological processes underlying the priming effects of motor imagery (MI) on force performance remain poorly understood. Here, we tested whether the priming effects of embedded MI practice involved short-term changes in corticomotor connectivity. In a within-subjects counterbalanced experimental design, participants (n = 20) underwent a series of experimental sessions consisting of successive maximal isometric contractions of elbow flexor muscles. During inter-trial rest periods, we administered MI, action observation (AO), and a control passive recovery condition. We collected electromyograms (EMG) from both agonists and antagonists of the force task, in addition to electroencephalographic (EEG) brain potentials during force trials. Force output was higher during MI compared to AO and control conditions (both p < 0.01), although fatigability was similar across experimental conditions. We also found a weaker relationship between triceps brachii activation and force output during MI and AO compared to the control condition. Imaginary coherence topographies of alpha (8−12 Hz) oscillations revealed increased connectivity between EEG sensors from central scalp regions and EMG signals from agonists during MI, compared to AO and control. Present results suggest that the priming effects of MI on force performance are mediated by a more efficient cortical drive to motor units yielding reduced agonist/antagonist coactivation.

Impact of Motor-Cognitive Interventions on Selected Gait and Balance Outcomes in Older Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

Efficient performance of most daily activities requires intact and simultaneous execution of motor and cognitive tasks. To mitigate age-related functional decline, various combinations of motor and cognitive training have shown promising results. The aim of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to evaluate the efficacy of different types of motor-cognitive training interventions (e.g., sequential and simultaneous) on selected functional outcomes in healthy older adults.

Methods

Six online academic databases were used to retrieve eligible RCTs up to April 2021, following PRISMA guidelines and PICO criteria. A random-effects model was used for all meta-analyses conducted on selected functional outcomes: single- and dual-task gait speed, the Timed Up and Go Test (TUG), and Berg Balance Scale (BBS) score. Effect size (ES) was calculated as Hedges' g and interpreted as: trivial: <0.20, small: 0.20–0.60, moderate: 0.61–1.20, large: 1.21–2.00, very large: 2.01–4.00 or extremely large >4.00.

Results

From 2,546 retrieved records, 91 RCTs were included for meta-analysis (n = 3,745 participants; 64.7–86.9 years). The motor-cognitive interventions included differed according to the type of training (e.g., sequential, simultaneous with additional cognitive task or exergame training. The results showed that motor-cognitive interventions can improve gait speed under single-task conditions (small ES = 0.34, P = 0.003). The effect of the intervention was moderated by the type of control group (Q = 6.203, P = 0.013): passive (moderate ES = 0.941, P = 0.001) vs. active controls (trivial ES = 0.153, P = 0.180). No significant effect was found for dual-task walking outcomes (P = 0.063). Motor-cognitive intervention had a positive effect on TUG (small ES = 0.42, P < 0.001), where the effect of intervention was moderated by control group [passive (moderate ES = 0.73, P = 0.001) vs. active (small ES = 0.20, P = 0.020)], but not by the type of training (P = 0.064). Finally, BBS scores were positively affected by motor-cognitive interventions (small ES = 0.59, P < 0.001) with however no significant differences between type of control group (P = 0.529) or intervention modality (P = 0.585).

Conclusions

This study provides evidence for the effectiveness of various types of motor-cognitive interventions on performance-based measures of functional mobility in healthy older adults. With respect to significant effects, gait speed under single-task condition was improved by motor-cognitive interventions, but the evidence shows that this type of intervention is not necessarily more beneficial than motor training alone. On the other hand, motor-cognitive interventions are better at improving multicomponent tasks of dynamic balance and mobility function, as measured by the TUG. Because of substantial heterogeneity and the current limited availability of different types of interventions, the conclusions should be interpreted with caution.

The Time Course of Quadriceps Strength Recovery After Total Knee Arthroplasty Is Influenced by Body Mass Index, Sex, and Age of Patients: Systematic Review and Meta-Analysis

Introduction

For patients with osteoarthritis who have undergone total knee arthroplasty (TKA), quadriceps strength is a major determinant of general physical function regardless of the parameters adopted for functional assessment. Understanding the time course of quadriceps strength recovery and effectiveness of different rehabilitation protocols is a must. Therefore, the aim of this study was to: (i) determine the magnitude of maximal voluntary strength (MVS) loss and the time course of recovery of the quadriceps muscle following TKA, (ii) identify potential moderators of strength outcomes, and (iii) investigate whether different rehabilitation practices can moderate the strength outcomes following TKA, respectively.

Design

General scientific databases and relevant journals in the field of orthopedics were searched, identifying prospective studies that investigated quadriceps’ MVS pre-to post-surgery.

Results

Seventeen studies with a total of 832 patients (39% males) were included. Results showed that in the early post-operative days, the involved quadriceps’ MVS markedly declined, after which it slowly recovered over time in a linear fashion. Thus, the greatest decline of the MVS was observed 3 days after TKA. When compared to pre-operative values, the MVS was still significantly lower 3 months after TKA and did not fully recover up to 6 months following TKA. Furthermore, a meta-regression analysis identified that the variables, time point of evaluation, patient age, sex, and BMI, significantly moderate the MVS of the quadriceps muscle.

Conclusion

The analyzed literature data showed that the decrease in strength of the involved quadriceps muscles following TKA is considerable and lasts for several months post-surgery. Therefore, we recommend to specifically target the strengthening of knee extensor muscles, preserve motor control, and apply appropriate nutrition to ensure a holistic quadriceps muscle recovery. Since age, sex, and BMI were found to be moderating factors in patients’ recovery, further research should include specific analyses considering these moderators.

Does mental practice or mirror therapy help prevent functional loss after distal radius fracture? A randomized controlled trial

STUDY DESIGN

A randomized, single-blinded controlled trial.

INTRODUCTION

Therapy results after distal radius fractures (DRF) especially with older patients are often suboptimal. One possible approach for counteracting the problems are motor-cognitive training interventions such as Mental Practice (MP) or Mirror Therapy (MT), which may be applied in early rehabilitation without stressing the injured wrist.

PURPOSE OF THE STUDY

The aim of the study is to investigate the effects of MP and MT on wrist function after DRF. The pilot study should furthermore provide information about the feasibility of these methods.

METHODS

Thirty-one women were assigned either to one of the two experimental groups (MP, MT) or to a control group (relaxation intervention). The participants completed a training for six weeks, administered at their homes. Measurements were taken at four times (weeks 0, 3, 6 and 12) to document the progression in subjective function (PRWE, QuickDASH) and objective constraints of the wrist (ROM, grip strength) as well as in health-related quality of life (EQ-5D).

RESULTS

The results indicated that both experimental groups showed higher improvements across the intervention period compared to the control group; e.g. PRWE: MT 74.0%, MP 66.2%, CG 56.9%. While improvements in grip strength were higher for the MP group, the MT group performed better in all other measures. However, time by group interactions approached significance at best; e.g. ROM: P = .076; η_p² = .141.

CONCLUSION

The superiority of MP as well as MT supports the simulation theory. Motor-cognitive intervention programs are feasible and promising therapy supplements, which may be applied in early rehabilitation to counteract the consequences of immobilization without stressing the injured wrist.

The effects of preoperative rehabilitation on pain and functional outcome after total knee arthroplasty: a meta-analysis of randomized controlled trials

Background

There have been controversial findings for the effectiveness of rehabilitation before operation after total knee arthroplasty (TKA). This study aimed to conduct an updated, comprehensive systematic review. On that basis, the review was to be combined with meta-analysis to measure the effects of rehabilitation before operation on functions and pain after TKA.

Methods

Articles were searched by using Central Register of Controlled Trials (CENTRAL), Web of Science, EMBASE, Cochrane, Pubmed, CNKI, Wanfang, Weipu and the Chinese Biomedical Database from the beginning to December 10, 2021. The major outcomes included pain, knee flexion and extension, as well as knee range of motion (ROM). Secondary outcomes included timed-up-and-go (TUG), 6-min walk, and patient-reported functional outcome (the Knee Injury and Osteoarthritis Outcome Score (KOOS) or Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)). Third outcomes included the length of hospital stay.

Results

Nineteen studies recruiting 1008 patients satisfied with the inclusion criteria. Significant difference was identified in knee flexion, TUG, KOOS (knee-associated life quality and functions in sports and recreation), as well as the length of hospital stay (P < 0.05). Insignificant statistical difference was identified in pain, 6-min walk, ROM, knee extension, KOOS (pain, symptoms and function of daily living) after TKA between the two groups. No difference was found between the groups in WOMAC.

Conclusions

Preoperative rehabilitation could significantly shorten hospital stay, whereas there is not any conclusive evidence of the improvement of postoperative functions. Accordingly, in-depth high-quality studies should be conducted to confirm the effectiveness of preoperative rehabilitation in patients having received TKA.

Motor Imagery and Action Observation as Appropriate Strategies for Home-Based Rehabilitation: A Mini-Review Focusing on Improving Physical Function in Orthopedic Patients

Dynamic stability of the knee and weakness of the extensor muscles are considered to be the most important functional limitations after anterior cruciate ligament (ACL) injury, probably due to changes at the central (cortical and corticospinal) level of motor control rather than at the peripheral level. Despite general technological advances, fewer contraindicative surgical procedures, and extensive postoperative rehabilitation, up to 65% of patients fail to return to their preinjury level of sports, and only half were able to return to competitive sport. Later, it becomes clear that current rehabilitation after knee surgery is not sufficient to address the functional limitations after ACL reconstruction even years after surgery. Therefore, new therapeutic tools targeting the central neural system, i.e., the higher centers of motor control, should be investigated and integrated into current rehabilitation practice. To improve motor performance when overt movement cannot be fully performed (e.g., due to pain, impaired motor control, and/or joint immobilization), several techniques have been developed to increase physical and mental activation without the need to perform overt movements. Among the most popular cognitive techniques used to increase physical performance are motor imagery and action observation practices. This review, which examines the available evidence, presents the underlying mechanisms of the efficacy of cognitive interventions and provides guidelines for their use at home.

Sport psychology and performance meta-analyses: A systematic review of the literature

Sport psychology as an academic pursuit is nearly two centuries old. An enduring goal since inception has been to understand how psychological techniques can improve athletic performance. Although much evidence exists in the form of meta-analytic reviews related to sport psychology and performance, a systematic review of these meta-analyses is absent from the literature. We aimed to synthesize the extant literature to gain insights into the overall impact of sport psychology on athletic performance. Guided by the PRISMA statement for systematic reviews, we reviewed relevant articles identified via the EBSCOhost interface. Thirty meta-analyses published between 1983 and 2021 met the inclusion criteria, covering 16 distinct sport psychology constructs. Overall, sport psychology interventions/variables hypothesized to enhance performance (e.g., cohesion, confidence, mindfulness) were shown to have a moderate beneficial effect (d = 0.51), whereas variables hypothesized to be detrimental to performance (e.g., cognitive anxiety, depression, ego climate) had a small negative effect (d = -0.21). The quality rating of meta-analyses did not significantly moderate the magnitude of observed effects, nor did the research design (i.e., intervention vs. correlation) of the primary studies included in the meta-analyses. Our review strengthens the evidence base for sport psychology techniques and may be of great practical value to practitioners. We provide recommendations for future research in the area.

Effectiveness of motor imagery for improving functional performance after total knee arthroplasty: a systematic review with meta-analysis

Background

The aim of this study was to appraise the effects of motor imagery on the functional performance improvement among total knee arthroplasty patients systematically. We hypothesized a relatively greater recovery in the motor imagery group.

Methods

Medline (Ovid), Embase and Cochrane Controlled Register of Trials (CENTRAL) were searched from inception to October 1st, 2021. We included randomized controlled trials evaluating the effects of motor imagery on the functional recovery among total knee arthroplasty patients. Measurements included range of motion, strength intensity, Visual Analogue Scale, Time Up and Go Test, Oxford Knee Score, Western Ontario and McMaster Universities Osteoarthritis Index, all of which were evaluated before and after intervention. Mean differences (MD) or standard mean differences (SMD) and 95% confidence intervals (CI) were calculated. The Cochrane risk of bias tool was used to assess the risk of bias.

Results

Six studies with 168 patients were included for the meta-analysis. The SMD of strength intensity was increased (SMD = 0.90, 95% CI = [0.47]–[1.32], P < 0.001). The SMD of Visual Analogue Scale was reduced (SMD =  − 0.91; 95% CI = [− 1.29]–[− 0.52], P < 0.001). The SMD of Time Up and Go Test was reduced (SMD =  − 0.56, 95% CI = [− 0.94]–[− 0.19], P = 0.003). The MD of Oxford Knee Score was slightly increased (MD = 0.79-point, 95% CI = [− 0.31]–[1.88], P = 0.159). The outcomes of range of motion, Western Ontario and McMaster Universities Osteoarthritis Index were described according to the original data.

Conclusion

Compared with control therapy, motor imagery in the intervention group achieved an effective treatment for strength enhancement, pain reduction and physical activities improvement. More large-scale, prospective researches are needed in the future.

Trial registration: The PROSPERO trial registration number is CRD42021250996.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-02946-4.

Motor effects of movement representation techniques and cross-education: a systematic review and meta-analysis

INTRODUCTION

The objective was to assess the impact of movement representation techniques (MRT) through motor imagery (MI), action observation (AO) and visual mirror feedback (VMF) and cross-education training (CE) on strength, range of motion (ROM), speed, functional state and balance during experimental immobilization processes in healthy individuals, in patients with injuries that did not require surgery and in those with surgical processes that did or did not require immobilization.

EVIDENCE ACQUISITION

MEDLINE, EMBASE, CINAHL and Google Scholar were searched. Thirteen meta-analyses were conducted.

EVIDENCE SYNTHESIS

Regarding the immobilized participants, in the healthy individuals, MI showed significant results regarding maintenance of strength and ROM, with low-quality evidence. Regarding the process with no immobilization, VMF and MI techniques showed significant changes in maintaining ROM in patients with injury without surgery, with very low-quality evidence. Results had shown that MI demonstrated significantly higher maintenance of strength and speed in patients undergoing surgery, with low-quality evidence. No significant results were found in ROM. Low-quality evidence showed better results in AO plus usual care compared with usual treatment in isolation with respect to maintenance of functional state and balance. CE training demonstrated maintenance of strength in patients undergoing surgery, with moderate evidence; however, not in healthy experimentally immobilized individuals. VMF did not show significant results in maintaining ROM after surgery without immobilization, nor did MI in maintaining strength after surgery and immobilization.

CONCLUSIONS

MRT and CE training have been shown to have a significant impact on the improvement of various motor variables and on physical maintenance in general.

A Systematic Review of the Sport Psychology Mixed Martial Arts Literature: Replication and Extension

MMA is a global sport with a growing body of psychological literature. Our main objective was to replicate and extend a past review concerning the sport psychology literature with MMA participants. We conducted our electronic search in EBSCO with the following databases: SPORTDiscus, PsycINFO, ERIC, and Psychology and Behavioral Sciences Collection. Our eligibility criteria were research articles (a) found in academic journals, (b) with MMA participants, and (c) at least one topic found in sport psychology literature. After conducting a PRISMA-guided search, 16 studies met our inclusion criteria. The studies spanned from 2011 to 2021, with 795 MMA participants from the USA (n = 7), Brazil (n = 4), and one study each from Czechia, Poland, Spain, Sweden, and the United Kingdom. From studies reporting mean ages, MMA participants were in their mid-20s (M = 26.55 ± 2.38 years of age). The results section includes risk of bias ratings across five areas (i.e., subject selection, sample’s MMA background, participant anonymity, data collection procedures, and questionnaire or qualitative theme reporting). More risk of bias concerns resulted with the quantitative than qualitative articles. To best represent the studies, we presented separate results tables with many specifics for both the quantitative (i.e., topic, main analysis, time frame, summary of results, and meaningfulness) and qualitative studies (topic, main analysis, time frame, and main themes). The included studies covered a variety of historic and meta-analyzed topics such as confidence, mood, motivations, and social facilitation. Based on our review, we discussed the literature strengths and limitations, and suggested future research directions. Last, we provided practical points for both MMA participants and their trainers.

Effects of motor imagery on strength, range of motion, physical function, and pain intensity in patients with total knee arthroplasty: A systematic review and meta-analysis

BACKGROUND

In the early stages of total knee arthroplasty (TKA) rehabilitation, in which physical function in general can be affected, motor imagery (MI) might play a relevant role.

OBJECTIVE

To assess the impact of MI on strength, active range of motion (ROM), pain intensity, and physical function in patients with TKA.

METHODS

We conducted a systematic review and meta-analysis of randomised controlled trials. Pooled effects were calculated as standardised mean differences (SMDs) and 95% confidence intervals (CIs) for the relevant outcomes using random effects model. The certainty of evidence was assessed with GRADE approach.

RESULTS

This review included 7 articles. The addition of MI to standard therapy, based on low quality of evidence, showed a moderate increase in quadriceps strength (4 studies; SMD: 0.88; 95% CI: 0.42, 1.34) and a small reduction in pain intensity (SMD: 0.63; 95% CI: 0.08, 1.19). It is unclear whether MI can provide beneficial effects for active ROM and function.

CONCLUSIONS

There is low to very low-quality evidence that adding an MI intervention to standard rehabilitation for patients with TKA may improve quadriceps strength and pain intensity, but the effects of MI on ROM and physical function is unclear.

Ain't Just Imagination! Effects of Motor Imagery Training on Strength and Power Performance of Athletes during Detraining

PURPOSE

This study aimed to investigate the effects of motor imagery (MI) training on strength and power performances of professional athletes during a period of detraining caused by the COVID-19 outbreak.

METHODS

Thirty male professional basketball players (age, 26.1 ± 6.2 yr) were randomly assigned to three counterbalanced groups: two MI training groups, who completed imagery training by mentally rehearsing upper and lower limb resistance training exercises loaded with either 85% of one repetition maximum (85%1RM) or optimum power loads (OPL), or a control group. For six consecutive weeks, although all groups completed two weekly sessions of high-intensity running, only the MI groups performed three additional MI sessions a week. Maximal strength and power output were measured through 1RM and OPL assessments in the back squat and bench press exercises with a linear positioning transducer. Vertical jump and throwing capabilities were assessed with the countermovement jump and the seated medicine ball throw tests, respectively. Kinesthetic and visual imagery questionnaires, and chronometry and rating of perceived effort scores were collected to evaluate MI vividness, MI ability, and perceived effort.

RESULTS

Physical performances improved significantly following both MI protocols (range, ~2% to ~9%), but were reduced in the control group, compared with preintervention (P ≤ 0.016). Moreover, interactions (time-protocol) were identified between the two MI groups (P ≤ 0.001). Whereas the 85%1RM led to greater effects on maximal strength measures than the OPL, the latter induced superior responses on measures of lower limb power. These findings were mirrored by corresponding cognitive and psychophysiological responses.

CONCLUSIONS

During periods of forced detraining, MI practice seems to be a viable tool to maintain and increase physical performance capacity among professional athletes.

Anticipatory Energization Revealed by Pupil and Brain Activity Guides Human Effort-Based Decision Making

An organism's fitness is determined by how it chooses to adapt to effort in response to challenges. Exertion of effort correlates with activity in dorsomedial prefrontal cortex (dmPFC) and noradrenergic pupil dilation, but little is known about the role of these neurophysiological processes for decisions about future efforts, they may provide anticipatory energization to help us accept the challenge or a cost representation that is weighted against the expected rewards. Here, we provide evidence for the former, by measuring pupil and functional magnetic resonance imaging (fMRI) brain responses while 52 human participants (29 females) chose whether to exert efforts to obtain rewards. Both pupil-dilation rate and dmPFC fMRI activity increased with anticipated effort level, and these increases differ depending on the choice outcome: they were stronger when participants chose to accept the challenge compared with when the challenge was declined. Crucially, the choice-dependent modulation of pupil and brain-activity effort representations were stronger in participants whose behavioral choices were more sensitive to effort. Our results identify a process involving the peripheral and central human nervous system that simulates the required energization before overt response, suggesting a role in guiding effort-based decisions.SIGNIFICANCE STATEMENT The brain's arousal system tracks the effort we engage in during strenuous activity. But much less is known about what role this effort signaling may play when we decide whether to exert effort in the future. Here, we characterize pupil-linked arousal and brain signals that guide decisions whether to engage in effort to gain money. During such choices, increases in brain activity and pupil dilation correlated with the effort involved in the chosen option, and these increases were stronger when people decided to accept the effort compared with when they rejected it. These results suggest that the brain arousal system guides decisions by energizing the organism for the prospective challenge.

Feasibility of motor imagery and effects of activating and relaxing practice on autonomic functions in healthy young adults: A randomised, controlled, assessor-blinded, pilot trial

Introduction

Motor imagery (MI) is the mental rehearsal of a motor task. Between real and imagined movements, a functional equivalence has been described regarding timing and brain activation. The primary study aim was to investigate the feasibility of MI training focusing on the autonomic function in healthy young people. Further aims were to evaluate participants’ MI abilities and compare preliminary effects of activating and relaxing MI on autonomic function and against controls.

Methods

A single-blinded randomised controlled pilot trial was performed. Participants were randomised to the activating MI (1), relaxing MI (2), or control (3) group. Following a MI familiarisation, they practiced home-based kinaesthetic MI for 17 minutes, 5 times/week for 2 weeks. Participants were called once for support. The primary outcome was the feasibility of a full-scale randomised controlled trial using predefined criteria. Secondary outcomes were participants’ MI ability using the Movement Imagery Questionnaire-Revised, mental chronometry tests, hand laterality judgement and semi-structured interviews, autonomic function.

Results

A total of 35 participants completed the study. The feasibility of a larger study was confirmed, despite 35% attrition related to the COVID-19 pandemic. Excellent MI capabilities were seen in participants, and significant correlations between MI ability measures. Interview results showed that participants accepted or liked both interventions. Seven major themes and insider recommendations for MI interventions emerged. No significant differences and negligible to medium effects were observed in MI ability or autonomic function between baseline and post-intervention measures or between groups.

Conclusions

Results showed that neither activating nor relaxing MI seems to change autonomic function in healthy individuals. Further adequately powered studies are required to answer open questions remaining from this study. Future studies should investigate effects of different MI types over a longer period, to rule out habituation and assess autonomic function at several time points and simultaneously with MI.

Motor imagery in congenital hemiplegia: Impairments are not universal

BACKGROUND

Motor imagery (MI) training may benefit children with congenital hemiplegia, but reports on MI ability are mixed. This study considered individual patterns of performance to better understand MI ability in children with hemiplegia.

METHOD

Twenty children with hemiplegia (7-13 years; 10 with right hemiplegia), completed a MI task, IQ estimate and functional tests. Children with hemiplegia scoring above chance on the MI task were compared to a group of age-matched peers. The performance patterns of those scoring below chance were considered individually.

RESULTS

Three children with right hemiplegia were excluded due to low IQ. Seven of 10 children with left hemiplegia and three of seven with right hemiplegia performed MI at an equivalent level to peers without hemiplegia. The seven children with hemiplegia who scored significantly below chance scored lower on functional tests, but differences here failed to reach an adjusted significance level. Four of the seven appeared engaged in MI, but performed very poorly. The remaining three had unique performance patterns explored in more detail.

CONCLUSION

Motor imagery deficits are not universally observed in children with congenital hemiplegia and individual performance should be examined before completing group analyses. Recommendations for exclusions and reporting in future studies are made.

Effects of TheraBand and Theratube Eccentric Exercises on Quadriceps Muscle Strength and Muscle Mass in Young Adults

Purpose

This study was aimed at comparing the effects of TheraBand and theratube eccentric exercises on quadriceps muscle strength in young adults.

Methods

Thirty young adults (19 females, 11 males) participated in this pretest-posttest experimental study. Participants were randomly assigned to one of the two groups: TheraBand and theratube groups. They received the training intervention 3 times a week for 4 weeks (12 sessions) with progression after 2 weeks. Maximum eccentric quadriceps strength was assessed using the Biodex isokinetic dynamometer system. Additionally, quadriceps muscle mass was measured using a tape.

Results

Both groups showed a significant improvement in the peak torque of the eccentric isokinetic quadriceps' strength after weeks 2 and 4. Strength change in the quadriceps was nonsignificant in the theratube group compared to the TheraBand group after 4 weeks of training (p < 0.05). There was no increase in muscle mass during the 4 weeks of training in any group (p > 0.05).

Conclusion

Both the TheraBand and theratube are equally effective in the strengthening of the quadriceps muscle in young adults. Therefore, either the TheraBand or theratube may be used according to the availability and feasibility of the subjects for training intervention.

Does partial activation of the neuromuscular system induce cross-education training effect? Case of a pilot study on motor imagery and neuromuscular electrical stimulation

INTRODUCTION

Cross education defines the gains observed in the contralateral limb following unilateral strength training of the other limb. The present study questioned the neural mechanisms associated with cross education following training by motor imagery (MI) or submaximal neuromuscular electrical stimulation (NMES), both representing a partial activation of the motor system as compared to conventional strength training.

METHODS

Twenty-seven participants were distributed in three groups: MI, NMES and control. Training groups underwent a training program of ten sessions in two weeks targeting plantar flexor muscles of one limb. In both legs, neuromuscular plasticity was assessed through maximal voluntary isometric contraction (MViC) and triceps surae electrophysiological responses evoked by electrical nerve stimulation (H-reflexes and V-waves).

RESULTS

NMES and MI training improved MViC torque of the trained limb by 11.3% (P < 0.001) and 13.8% (P < 0.001), respectively. MViC of the untrained limb increased by 10.3% (P < 0.003) in the MI group only, accompanied with increases in V-waves on both sides. In the NMES group, V-waves only increased in the trained limb. In the MI group, rest H-reflexes increased in both the trained and the untrained triceps suraes.

CONCLUSION

MI seems to be effective to induce cross education, probably because of the activation of cortical motor regions that impact the corticospinal neural drive of both trained and untrained sides. Conversely, submaximal NMES did not lead to cross education. The present results emphasize that cross education does not necessarily require muscle activity of the trained limb.

Using motor imagery practice for improving motor performance - A review

Motor imagery practice is a current trend, but there is a need for a systematic integration of neuroscientific advances in the field. In this review, we describe the technique of motor imagery practice and its neural representation, considering different fields of application. The current practice of individualized motor imagery practice schemes often lacks systematization and is mostly based on experience. We review literature related to motor imagery practice in order to identify relevant modulators of practice effects like previous experience in motor training and motor imagery practice, the type of motor task to be trained, and strategies to increase sensory feedback during physical practice. Relevant discrepancies are identified between neuroscientific findings and practical consideration of these findings. To bridge these gaps, more effort should be directed at analyzing the brain network activities related to practically relevant motor imagery practice interventions.

Insights into the combination of neuromuscular electrical stimulation and motor imagery in a training-based approach

Introduction

Training stimuli that partially activate the neuromuscular system, such as motor imagery (MI) or neuromuscular electrical stimulation (NMES), have been previously shown as efficient tools to induce strength gains. Here the efficacy of MI, NMES or NMES + MI trainings has been compared.

Methods

Thirty-seven participants were enrolled in a training program of ten sessions in 2 weeks targeting plantar flexor muscles, distributed in four groups: MI, NMES, NMES + MI and control. Each group underwent forty contractions in each session, NMES + MI group doing 20 contractions of each modality. Before and after, the neuromuscular function was tested through the recording of maximal voluntary contraction (MVC), but also electrophysiological and mechanical responses associated with electrical nerve stimulation. Muscle architecture was assessed by ultrasonography.

Results

MVC increased by 11.3 ± 3.5% in NMES group, by 13.8 ± 5.6% in MI, while unchanged for NMES + MI and control. During MVC, a significant increase in V-wave without associated changes in superimposed H-reflex has been observed for NMES and MI, suggesting that neural adaptations occurred at supraspinal level. Rest spinal excitability was increased in the MI group while decreased in the NMES group. No change in muscle architecture (pennation angle, fascicle length) has been found in any group but muscular peak twitch and soleus maximal M-wave increased in the NMES group only.

Conclusion

Finally, MI and NMES seem to be efficient stimuli to improve strength, although both exhibited different and specific neural plasticity. On its side, NMES + MI combination did not provide the expected gains, suggesting that their effects are not simply cumulative, or even are competitive.

Home-based motor imagery intervention improves functional performance following total knee arthroplasty in the short term: a randomized controlled trial

BACKGROUND

Motor imagery (MI) is effective in improving motor performance in the healthy asymptomatic adult population. However, its possible effects among older orthopaedic patients are still poorly investigated. Therefore, this study explored whether the addition of motor imagery to routine physical therapy reduces the deterioration of quadriceps muscle strength and voluntary activation (VA) as well as other variables related to motor performance in patients after total knee arthroplasty (TKA).

METHODS

Twenty-six patients scheduled for TKA were randomized to either MI practice combined with routine physical therapy group (MIp) or to a control group receiving physical therapy alone (CON). MIp consisted of maximal voluntary isometric contraction (MViC) task: 15 min/day in the hospital, then 5 times/week in their homes for 4 weeks. MViC and VA of quadriceps muscle, knee flexion and extension range of motion, pain level, along with a Timed Up-and-Go Test (TUG) and self-reported measure of physical function (assessed using the Oxford Knee Score questionnaire [OKS]) were evaluated before (PRE) and 1 month after surgery (POST).

RESULTS

Significantly better rehabilitation outcomes were evident on the operated leg for the MIp group compared to CON: at POST, the MIp showed lower strength decrease (p = 0.012, η2 = 0.237) and unaltered VA, significantly greater than CON (p = 0.014, η2 = 0.227). There were no significant differences in knee flexion and extension range of motion and pain level (p > 0.05). Further, MIp patients performed better in TUG (p < 0.001, η2 = 0.471) and reported better OKS scores (p = 0.005, η2 = 0.280). The non-operated leg showed no significant differences in any outcomes at POST (all p > 0.05). In addition, multiple linear regression analysis showed that failure of voluntary activation explained 47% of the quadriceps muscle strength loss, with no significant difference in perceived level of pain.

CONCLUSION

MI practice, when added to physical therapy, improves both objective and subjective measures of patients' physical function after TKA, and facilitates transfer of MI strength task on functional mobility.

TRIAL REGISTRATION

Retrospectively registered on ClinicalTrials.gov NCT03684148.

Effect of action observation therapy on motor function in children with cerebral palsy: a systematic review of randomized controlled trials with meta-analysis

Objective:

To evaluate the evidence of using Action Observation Therapy in the rehabilitation of children with Cerebral Palsy.

Study design:

Systematic review with meta-analysis of Randomised Controlled Trials.

Methods:

For the purpose of identifying relevant studies, six databases were searched from inception until July 2020. The methodological quality was assessed by Physiotherapy Evidence Database scale. The outcomes were classified within the framework of the International Classification of Functioning. A pooled meta-analysis was performed on studies that demonstrated homogeneity.

Results:

Twelve randomised controlled trials with 307 participants were included with six of them were included in the meta-analysis. Non-significant difference between the groups was demonstrated by meta-analysis. Results of capacity assessed in post treatment and follow up evaluation were (0.06, –0.22 to 0.34, 95% (CI); P = 0.69 and (–0.35, –0.96 to 0.27, 95% (CI); P = 0.27); respectively. Actual performance in post-treatment and follow up were (0.10, –0.22 to 0.48, 95% (CI); P = 0.62) and (0.01, –0.40 to 0.41, 95% (CI); P = 0.97); respectively. Perceived performance evaluated using (ABILHAND-KIDS) were (0.30, –0.28 to 0.89, 95% (CI); P = 0.31) and (0.15, –0.43 to 0.73, 95% (CI); P = 0.61) for post treatment and follow up; respectively. Overall effect on activity domain was (0.08, –0.11 to 0.28, 95% (CI); P = 0.86) immediately and (0.04, –0.33 to 0.26, 95% (CI); P = 0.49) at follow-up; respectively.

Conclusion:

No evidence of benefit had been found to draw a firm conclusion regarding the effectiveness of action observation therapy in the rehabilitation of children with cerebral palsy due to limitations in methodological quality and variations between studies.

Mental Simulation Practice Has Beneficial Effects on Patients' Physical Function Following Lower Limb Arthroplasty: A Systematic Review and Meta-analysis

OBJECTIVE

To determine the effectiveness of mental simulation practice (MSP) on measures of physical function recovery in patients who have undergone a joint replacement surgery of lower limbs.

DATA SOURCES

A systematic review was conducted using CINAHL, PubMed/MEDLINE, Embase, SPORTDiscus, PEDro, Cochrane Register of Controlled Trials, and Google Scholar from the earliest record until August 16, 2019.

STUDY SELECTION

The following inclusion criteria were used to determine eligibility for studies: (1) randomized and matched controlled trials recruiting men and women who underwent primary unilateral joint arthroplasty; (2) the study examined the effects of MSP intervention on measures of physical function recovery (both performance-based and patient self-reported); and (3) measures of interest were compared between MSP and control groups. A total of 8 papers (7 studies) met the inclusion criteria and were included.

DATA EXTRACTION

Data were extracted by 1 reviewer and checked by a second reviewer, independently.

DATA SYNTHESIS

When compared with standard physical therapy (SPT), MSP showed an effect on physical function in general (effect size [ES], 0.67; 95% confidence interval [CI], 0.38-0.96; n=7), maximal voluntary strength of knee extensor muscles of the affected leg (ES, 1.41; 95% CI, 0.64-2.18; n=2), brisk walking speed (ES, 1.20; 95% CI, 0.58-1.83; n=2), brisk walking speed with dual task (ES, 1.02; 95% CI, 0.41-1.63; n=2), timed up-to go test (ES, 0.96; 95% CI, 0.15-1.77; n=3), and active flexion of the affected leg (ES, 0.70; 95% CI, 0.29-1.11; n=4). Finally, meta-regression analysis revealed that the effects of MSP were significantly predicted only by total number of training sessions per study.

CONCLUSIONS

The present meta-analysis demonstrated that MSP intervention has multiple positive effects on measures of physical function recovery in patients who have undergone total knee or hip replacement surgery in comparison with SPT. Thus, MSP can be applied as an effective complementary therapy to SPT in physical rehabilitation of this specific population, especially in the early postacute and acute phase.

Comparative study of observed actions, motor imagery and control therapeutic exercise on the conditioned pain modulation in the cervical spine: a randomized controlled trial

Aim: The aim of this study was to compare the effects of cervical exercise, motor imagery (MI) and action observation (AO) of cervical exercise actions on conditioned pain modulation and pressure pain thresholds. The second objective was to assess the effects of these interventions on cervical motor activity (ranges of motion and muscle endurance), attention, and the ability to generate motor images.Study design: Single-blinded randomized controlled trial.Materials and methods: Fifty-four healthy subjects were randomly assigned to each group. Response conditioned pain modulation, pressure pain threshold, were the main variables. The secondary outcome measures included, cervical range of motion, Neck flexor endurance test, mental movement representation associated and psychosocial variables.Results: All groups showed significant differences in time factor for all evaluated variables (p < .01) except pressure pain threshold over the tibial region. The post hoc analysis revealed significant within-group differences in the AE and AO groups in conditioned pain modulation (p < .05), with medium effect size in time [AE (d -0.61); AO (d -0.74)].Conclusion: The results showed that within-group changes in conditioned pain modulation, cervical muscle endurance, and attention where founded only in the AE and AO groups. Variations in pain thresholds at pressure in the trapezium area were also obtained in the three groups. Changes in the ranges of flexion-extension and rotation movement were presented exclusively in the exercise group, and in the capacity to generate motor images only in the AO group. However, there was no difference in the pressure pain threshold over the tibial region.

Neurostructural correlates of strength decrease following total knee arthroplasty: A systematic review of the literature with meta-analysis

Recent literature suggests that alterations in both neural and structural components of the neuromuscular system are major determinants of knee extensor muscle weakness after total knee arthroplasty (TKA). Therefore, the goal of this study was to investigate the maximal voluntary strength (MVS), voluntary muscle activation (VMA), and the cross-sectional area (CSA) of the muscle, up to 33 months after the TKA.  We searched relevant scientific databases and literature for outcomes of interest, including quadriceps MVS, VMA, and CSA. Ten studies met the inclusion criteria and involved a total of 289 patients. The quality of the studies was evaluated by Methodological Index for Non-Randomized Studies (MINORS). Results showed that quadriceps MVS markedly declines in the early postoperative period, after which it slowly and linearly recovers over time. However, the same phenomenon was not observed for VMA and CSA, which were not significantly altered after the TKA. Furthermore, a meta-regression analysis revealed that the change in VMA accounted for 39% of the relative change in quadriceps strength (R2=0.39; p=0.015) in the early postoperative period. Patients treated with TKA had considerable weakness of the quadriceps muscle, which was detectable up to 3 months after surgery. Although the change in VMA largely explains quadriceps weakness, this change and CSA differences were not significant, suggesting that other neural correlates, such as hamstrings coactivation, might alter quadriceps muscle function. Thus, more attention should be paid to address VMA failure and coactivation of antagonist muscles.  More comprehensive rehabilitation approaches may be required to target the whole neural circuit controlling the motor action.

Using PETTLEP imagery as a simulation technique in nursing: Research and guidelines

One of the most valuable skill sets developed in nurse education is the ability to develop the clinical and practical skills learned. This can take various forms such as university-based practice, simulation and direct experience with patients. To this end imagery, a process where all of the senses are used to create or recreate an experience in the mind, could represent simulated practice of clinical skills. Research on imagery has indicated that the technique, when used to assist in the performance of skill based procedures carried out by nurses can be beneficial. However, guidelines are lacking in this area of simulated practice. In this article, we review current research on the topic of imagery in enhancing skilled performance and outline a model that can assist in conducting interventions. Furthermore, we consider how this could be implemented within a nursing environment to produce beneficial performance effects in both pre-registration and registered nurses.

Effects of Different Ratios of Physical and Mental Practice on Postural Control Improvement

Mental practice (MP) is a reliable alternative or complement to physical practice (PP) for the training of postural control. We address how MP should ideally be combined with PP. Participants were assigned to four experimental groups where MP/PP ratios during training varied from 0 to 100%. Performance improved only for demanding postural adjustments, regardless of MP/PP ratio, and learning was partially consolidated after a night of sleep. Findings reinforce the relevance of MP for the training of weight shifting and further suggest that MP alone can be as efficient as PP for the learning of certain complex postural adjustments.

Motor imagery training improves balance and mobility outcomes in older adults: a systematic review

QUESTION

Does motor imagery training improve measures of balance, mobility and falls in older adults without a neurological condition?

DESIGN

Systematic review and meta-analysis of randomised controlled trials.

PARTICIPANTS

Adults aged at least 60 years and without a neurological condition.

INTERVENTION

Three or more sessions of motor imagery training.

OUTCOME MEASURES

The primary outcomes were balance measures (such as single leg stance and Berg Balance scale) and mobility measures (such as gait speed and the Timed Up and Go test). Falls were a secondary outcome measure. Risk of bias was evaluated using the PEDro Scale, and overall quality of evidence was assessed using the Grades of Research, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Twelve trials including 356 participants were included in the systematic review and 10 trials (316 participants) were included in the meta-analyses. All trials included either apparently healthy participants or older adults after orthopaedic surgery. There was evidence that motor imagery training can significantly improve balance (SMD 1.03, 95% CI 0.25 to 1.82), gait speed (MD 0.13 m/s, 95% CI 0.04 to 0.22) and Timed Up and Go (MD 1.64 seconds, 95% CI 0.79 to 2.49) in older adults; however, the quality of evidence was very low to low. No data regarding falls were identified.

CONCLUSION

Motor imagery training improves balance and mobility in older adults who do not have a neurological condition. These results suggest that motor imagery training could be an adjunct to standard physiotherapy care in older adults, although it is unclear whether or not the effects are clinically worthwhile.

TRIAL REGISTRATION

PROSPERO CRD42017069954.

Specific and general adaptations following motor imagery practice focused on muscle strength in total knee arthroplasty rehabilitation: A randomized controlled trial

BACKGROUND

Motor imagery (MI) has been a widely used strategy in the past two decades to enhance physical capabilities among orthopaedic patients. However, its effectiveness is still questioned, since the demonstrated effects were likely task-dependent, with little evidence of transfer to tasks not specifically trained with MI.

OBJECTIVE

The aim of this study was to investigate whether an MI practice focused on maximal isometric knee extension strength, causes additional specific and general adaptations upon neuromuscular and functional variables when compared to conventional rehabilitation only, in patients submitted to total knee arthroplasty (TKA).

DESIGN

Parallel group randomized controlled clinical trial.

PARTICIPANTS

Thirty-four patients (56% man) submitted to TKA.

PROGRAM

Patients were randomly assigned to an MI practice group (MIp: 15 minutes per day/5 days per week in addition to routine physical therapy) or control group (CON) that performed routine physical therapy alone for four weeks.

OUTCOME MEASURES

The maximal isometric knee extension strength of the operated leg was defined as the primary outcome. Secondary outcomes were spatial and temporal gait parameters, 30-second chair sit-to-stand performance, a self-reported physical function assessed by the Lower Extremity Functional Scale (LEFS) questionnaire, and an MI ability score. All measurements were conducted before and one month after TKA.

RESULTS

Significant differences in treatment effects were observed for the MIp group compared to CON: the MIp showed less strength decrease (ES = 1.15, 95% CI: 0.32, 1.99, p = 0.022); faster self-selected speed under single (ES = 2.12, 95% CI: 1.16, 3.08, p = 0.001) and dual task (ES = 1.59, large, 95% CI: 0.67, 2.50, p = 0.002) conditions; brisk-pace gait speed during single (ES = 1.32, 95% CI: 0.47, 2.17, p = 0.020) and dual task conditions (ES = 1.31, large, 95% CI: 0.38, 2.23, p = 0.013); improved chair sit-to-stand (ES = 1.45, large, 95% CI: 0.58, 2.31, p = 0.004) performance; and a higher score on MI ability questionnaires for kinaesthetic imagery (KI) (ES = 0.55, 95% CI: -0.23, 1.34, p = 0.010) and internal visual imagery (EVI) (ES = 0.99, 95% CI: 0.18, 1.80, p = 0.039) scales, respectively. In addition, only MIp showed unaltered single and double support periods, as well as stride length and cadence during single task self-selected gait condition. Finally, analysis showed that the improved MI ability score achieved at the end of MI training was significantly correlated with the changes in the strength of the operated leg (kinaesthetic imagery: r = 0.741, p = 0.004; and internal visual imagery: r = 0.623, p = 0.023).

CONCLUSIONS

MI training, when added in a corollary to routine physical therapy, led to improvements in both specific and general adaptations that were related to patients' physical capabilities. While future studies must also evaluate the long-term effects, conducting MI training during acute and post-acute rehabilitation phases is advised, especially when the extent and range of physical exercise is limited or made impossible.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03684148.