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Motor imagery (MI) is the mental representation of a movement without its execution. It activates internal representations of the movement without external stimulus through different memory‐related processes. Although acute stress is frequent in the population and affects supraspinal structures essential for memory functionality, it is still unknown how that stress affects MI capacity and temporal congruence (TC) between execution and movement imagination. This study aimed to discover how acute stress may influence MI capacity and TC in the subscales of internal and external visual imagery and kinesthetic imagery. A double‐blind, randomized trial was conducted. Sixty‐two young, healthy subjects (mean age = 20.65 [2.54]; 39 females and 23 males) unfamiliar with the assessment and uses of MI were recruited. Participants were assigned by stratified randomization to the stress group or the control group. Stress was induced by the Maastricht Acute Stress Test (MAST), while the control group performed the MAST control protocol. MI capacity and TC were assessed before (t1) and after (t2) MAST stress or control using the Movement Imagery Questionnaire‐3 (MIQ‐3). Electrodermal activity and heart rate variability were further recorded as control variables to assess stress induction. Thirty subjects in the stress group and 26 subjects in the control group were analyzed. No significant group differences were observed when comparing MI capacity or TC in any subscales. These findings suggest that acute stress does not significantly affect MI capacity or TC in young, healthy, non‐experienced MI subjects. MI could thus be a relevant helpful technique in stressful situations. [ABSTRACT FROM AUTHOR]

Purpose: The ability to perform motor imagery (MI) might be impaired by the physical fatigue elicited during training. Interestingly, there is also theoretical support for a more limited influence of fatigue in the existing literature. Method: We evaluated MI ability before and after two exercise protocols: (i) a continuous exercise of 20 min performed on a cycle ergometer at 80% of the secondary ventilatory threshold (Continuous exercise), and (ii) an intermittent exercise of 20 min involving sprints at maximal intensity performed with regular intervals (Intermittent exercise). MI ability evaluations were performed using validated behavioral (mental chronometry) and psychometric (subjective reports) methods. MI ability evaluations included mental rehearsal of a motor sequence which involved the main effectors of the exercise protocols (walking), and mental rehearsal of a motor task which did not involve the main somatic effectors of the exercise protocols (pointing movements with the upper limbs). Results: Mental chronometry showed that MI ability was degraded only after Intermittent exercise, while self-report measures of MI vividness revealed that MI ability was primarily impaired during MI of the walking task. Conclusions: Present results suggest that Intermittent exercise engaging anaerobic processes of energy expenditure, but not Continuous exercise engaging aerobic processes of energy expenditure, impaired MI ability. Findings are discussed in relation to the internal models theory of motor simulation, specifically changes in current state of the motor system under the fatigued state-affecting motor predictions. Present findings may contribute to successful applications of MI training in sports and rehabilitation.

Background: Manual massage (MM) interventions can improve psychophysiological states of relaxation and well-being. In this context, robotic massage (RM) represents a promising, but currently understudied, solution. Hypothesis: Both MM and RM would improve flexibility of the hamstrings and lumbopelvic muscles and promote a psychophysiological state of relaxation through decreased sympathetic activity. Study Design: Single-blind randomized crossover trial. Level of Evidence: Level 2. Methods: A total of 21 participants experienced 2 massage interventions targeting back soft tissues. During a first condition, the intervention was performed by a physical therapist, whereas during a second condition the intervention was performed by a robot. We collected objective and subjective indexes of performances and well-being before and after each massage intervention. We also collected physical therapists' self-reports of perceived fatigue, tension, and ability to maintain the massage routine. Results: Skin conductance decreased from the pretest to the posttest in both conditions (partial R 2 = 0.44, 95% CI [0.30, 1.00], P < 0.01), although the decrease was more pronounced after MM. Whereas both interventions were associated with improved subjective sensations, eg, pain, warmth, well-being (partial R 2 = 0.08, 95% CI [0.06, 1.00], P < 0.01), MM yielded additional benefits compared with RM. The physical therapist reported greater fatigue and tension and reduced perceived massage efficiency along with repeated massage interventions. MM outperformed RM to elicit a psychophysiological state of relaxation. Conclusion: RM exhibited a pattern of changes comparable with that of MM, for both objective and subjective indexes of relaxation and well-being. Clinical Relevance: RM could represent a prophylactic option to prevent the onset of counterproductive fatigability in physical therapists. [ABSTRACT FROM AUTHOR]

There is now ample evidence that motor imagery contributes to improve motor performance and promote motor learning and recovery. During the last decades, a large number of experimental studies and imagery frameworks were designed to determine the critical key components for effective imagery interventions. The extent to which athletes often move slightly during motor imagery has spawned specific interest in imagery research from a conceptual perspective, hence challenging the traditional idea that imagery requires to remain motionless. While a wealth of research has extensively decoupled motor imagery from action, more recent imagery theories specifically considered that athletes can perform a dynamic form of imagery, by adopting a congruent body position and embodying spatial and/or temporal features of the movement without entirely performing it. Spurred by the wide use of this form of imagery by athletes and the promising related experimental research, the present paper aims at reviewing the impact and predictive positive effects of dynamic motor imagery on motor performance. Direct implications for applied work, including specific instructions that dynamic motor imagery might have during different stages of the coaching process of athletes, are further considered. A framework for the appropriate timing for delivering dynamic imagery interventions is finally proposed. [ABSTRACT FROM AUTHOR]

Limb movement direction can be inferred from local field potentials in motor cortex during movement execution. Yet, it remains unclear to what extent intended hand movements can be predicted from brain activity recorded during movement planning. Here, we set out to probe the directional-tuning of oscillatory features during motor planning and execution, using a machine learning framework on multi-site local field potentials (LFPs) in humans. We recorded intracranial EEG data from implanted epilepsy patients as they performed a four-direction delayed center-out motor task. Fronto-parietal LFP low-frequency power predicted hand-movement direction during planning while execution was largely mediated by higher frequency power and low-frequency phase in motor areas. By contrast, Phase-Amplitude Coupling showed uniform modulations across directions. Finally, multivariate classification led to an increase in overall decoding accuracy (>80%). The novel insights revealed here extend our understanding of the role of neural oscillations in encoding motor plans. A study using intracranial recordings in humans suggests that upcoming hand movements can be predicted by oscillatory brain features of the LFP signal. [ABSTRACT FROM AUTHOR]

Motor imagery (MI) training is used to improve motor performance in both patients and athletes. The putative link between personality and MI remains however largely underexplored. In this pilot study, 72 sports students performed MI and physical execution of a finger pointing task. MI ability was assessed through the mental chronometry paradigm that captured the temporal components of imagery, as well as self-report measures of imagery vividness and imagery ease. Personality dimensions were assessed with the five-factor model. Extraversion was found to be significantly correlated with MI ability as measured with mental chronometry (r =.37, p =.001) but not with imagery vividness (r = −.08, p =.481) or imagery ease (r = −.04, p =.741). The other personality dimensions were unrelated to MI ability (all p >.05). Based on these findings, we postulate that extravert individuals may have an advantage in controlling and maintaining the temporal aspect of mental movements. This may help extraverts to better benefit from imagery training. [ABSTRACT FROM AUTHOR]

When applied over the primary motor cortex (M1), anodal transcranial direct current stimulation (a-tDCS) could enhance the effects of a single motor imagery training (MIt) session on the learning of a sequential finger-tapping task (SFTT). This study aimed to investigate the effect of a-tDCS on the learning of an SFTT during multiple MIt sessions. Two groups of 16 healthy young adults participated in three consecutive MIt sessions over 3 days, followed by a retention test 1 week later. They received active or sham a-tDCS during a MIt session in which they mentally rehearsed an eight-item complex finger sequence with their left hand. Before and after each session, and during the retention test, they physically repeated the sequence as quickly and accurately as possible. Both groups (i) improved their performance during the first two sessions, showing online learning; (ii) stabilised the level they reached during all training sessions, reflecting offline consolidation; and (iii) maintained their performance level one week later, showing retention. However, no significant difference was found between the groups, regardless of the MSL stage. These results emphasise the importance of performing several MIt sessions to maximise performance gains, but they do not support the additional effects of a-tDCS. [ABSTRACT FROM AUTHOR]

Purpose: Brazilian jiu-jitsu is a martial art emphasizing ground combat with multiple ramifications to self-defense and military training. Some Brazilian jiu-jitsu athletes prefer fighting on their back (Guardadors), while others preferentially adopt a standing or kneeling position (Passadors). Whether the combat scenario leading to adopt a preferential or nonpreferential combat style influences the combat outcomes remains unexplored. Methods: In a counterbalanced design, 13 athletes performed simulated combats from either a congruent or incongruent scenario with regard to their preferred combat style. We collected combat scores from the official ranking system and measured upper- and lower-limb explosive performance before and after the combats, as well as the rating of perceived exertion and blood lactate concentrations to index fatigability. Results: Passadors had greater grip strength than Guardadors ( R p 2 =.23, P =.03), whereas Guardadors showed higher lower-limb performance ( R p 2 =.16, P =.05). When forced to combat as Passadors, Guardadors exhibited greater grip-strength impairment and a greater increase in perceived exertion ( R p 2 =.12, P =.04; R p 2 =.15, P =.05, respectively). They also had higher blood lactate concentrations ( R p 2 =.19, P =.02). Conclusion: Guardadors exhibited greater fatigability after fighting from an incongruent combat situation compared to Passadors, presumably due to greater difficulties to adjust to the loss of initiative when restricted to a primarily defensive role. Future studies should examine how combat style congruency might affect performance and influence recovery strategies during high-level competitive events. [ABSTRACT FROM AUTHOR]