Time course and temporal order of changes in movement kinematics during motor learning: effect of joint and instruction

60-Hour Sleep Deprivation Affects Submaximal but Not Maximal Physical Performance

The effect of 60-h sleep deprivation (SD) on physical performance and motor control was studied. Twenty cadets were measured for aerobic performance (VO₂) before and immediately after the SD period. Maximal strength and EMG of the knee extensor muscles were measured before and after 60 h of SD. Balance, reaction times and motor control were assessed every evening and morning during the SD period. Main effects were observed for heart rate (p = 0.002, partial eta squared: 0.669), VO₂ (p = 0.004, partial eta squared: 0.621), ventilation (p = 0.016, partial eta squared: 0.049), and lactate concentration (p = 0.022, partial eta squared: 0.501), whereas RER remained unaltered (p = 0.213, partial eta squared: 0.166). Pairwise comparisons revealed decreased values at submaximal loads in heart rate, VO₂, ventilation (all p < 0.05) but not in RER, whereas all of their respective maximal values remained unchanged. Moreover, pairwise comparisons revealed decreased lactate concentration at maximal performance but only at 8-min time point during submaximal workloads (p < 0.05). Pairwise comparisons of maximal strength, EMG and rate of force development revealed no change after SD. Main effects were observed for motor and postural control, as well as for reaction times (all p < 0.05), whereas pairwise comparison did not reveal a consistent pattern of change. In conclusion, motor control can mostly be maintained during 60-h SD, and maximal neuromuscular and aerobic performances are unaffected. However, submaximal cardiorespiratory responses seem to be attenuated after SD.

Influence of Perspective of Action Observation Training on Residual Limb Control in Naïve Prosthesis Usage

Prior work in amputees and partial limb immobilization have shown improved neural and behavioral outcomes in using their residual limb with prosthesis when undergoing observation-based training with a prosthesis-using actor compared to an intact limb. It was posited that these improvements are due to an alignment of user with the actor. It may be affected by visual angles that allow emphasis of critical joint actions which may promote behavioral changes. The purpose of this study was to examine how viewing perspective of observation-based training effects prosthesis adaptation in naïve device users. Twenty nonamputated prosthesis users learned how to use an upper extremity prosthetic device while viewing a training video from either a sagittal or coronal perspective. These views were chosen as they place visual emphasis on different aspects of task performance to the device. The authors found that perspective of actions has a significant role in adaptation of the residual limb while using upper limb prostheses. Perspectives that demonstrate elbow adaptations to prosthesis usage may enhance the functional motor outcomes of action observation therapy. This work has potential implications on how prosthetic device operation is conveyed to persons adapting to prostheses through action observation based therapy.

Translating the science into practice: shaping rehabilitation practice to enhance recovery after brain damage

The revolution in neuroscience provided strong evidence for learning-dependent neuroplasticity and presaged the role of motor learning as essential for restorative therapies after stroke and other disabling neurological conditions. The scientific basis of motor learning has continued to evolve from a dominance of cognitive or information processing perspectives to a blend with neural science and contemporary social-cognitive-psychological science, which includes the neural and psychological underpinnings of motivation. This transformation and integration across traditionally separate domains is timely now that clinician scientists are developing novel, evidence-based therapies to maximize motor recovery in the place of suboptimal solutions. We will review recent evidence pertaining to therapeutic approaches that spring from an integrated framework of learning-dependent neuroplasticity along with the growing awareness of protocols that directly address the patient's fundamental psychological needs. Of importance, there is mounting evidence that when the individual's needs are considered in the context of instructions or expectations, the learning/rehabilitation process is accelerated.

Inertial sensor real-time feedback enhances the learning of cervical spine manipulation: a prospective study

BACKGROUND

Cervical Spinal Manipulation (CSM) is considered a high-level skill of the central nervous system because it requires bimanual coordinated rhythmical movements therefore necessitating training to achieve proficiency. The objective of the present study was to investigate the effect of real-time feedback on the performance of CSM.

METHODS

Six postgraduate physiotherapy students attending a training workshop on Cervical Spine Manipulation Technique (CSMT) using inertial sensor derived real-time feedback participated in this study. The key variables were pre-manipulative position, angular displacement of the thrust and angular velocity of the thrust. Differences between variables before and after training were investigated using t-tests.

RESULTS

There were no significant differences after training for the pre-manipulative position (rotation p = 0.549; side bending p = 0.312) or for thrust displacement (rotation p = 0.247; side bending p = 0.314). Thrust angular velocity demonstrated a significant difference following training for rotation (pre-training mean (sd) 48.9°/s (35.1); post-training mean (sd) 96.9°/s (53.9); p = 0.027) but not for side bending (p = 0.521).

CONCLUSION

Real-time feedback using an inertial sensor may be valuable in the development of specific manipulative skill. Future studies investigating manipulation could consider a randomized controlled trial using inertial sensor real time feedback compared to traditional training.

Motor performance benefits of matched limb imitation in prosthesis users

Our previous work demonstrated that the action encoding parietofrontal network, which is crucial in planning and executing motor tasks, is less active in prosthesis users who imitate movements of intact actors (mismatched limb) versus prosthesis users (matched limb). Such activation could have behavioral consequences in prosthesis users rehabilitating with intact therapists. The goal was to identify behavioral effects of matched versus mismatched limb action imitation in naïve users of prostheses. Intact subjects donned a specially adapted prosthetic device to simulate the wrist and forearm movement that transradial amputees experience. While electrogoniometry was recorded, non-amputated prosthesis users (NAPUs) observed and imitated demonstrations of a skillful motor task performed by either an intact actor or NAPU. We hypothesized that NAPUs would elicit less motion variability when performing matched versus mismatched imitation. Matched imitation resulted in a significant decrease in shoulder motion variability compared with mismatched imitation. The matched group also developed elbow motion patterns similar to the NAPU demonstrator, while the mismatched group attempted patterns similar to the intact demonstrator. This suggests a behavioral advantage to matched imitation when adapting to a prosthetic device, as it yielded more consistent movements and facilitated development of new motor patterns. Further, these results suggest that when prosthesis users are faced with the impossible task of imitating movements of an intact hand, they perform this action with greater variability and poorer technique. This work has implications on how prosthetic device operation is conveyed to persons with amputation as their clinical interactions often involve mismatched limb imitation.

Kinetic analysis of expertise in spinal manipulative therapy using an instrumented manikin

OBJECTIVE

The goals of this study were to measure the kinetic profile of thrust in different groups of subjects with various levels of expertise and to quantify general coordination while performing thoracic spine manipulation.

PARTICIPANTS

A total of 43 students and chiropractors from the Chiropractic Department of the Université du Québec à Trois-Rivières participated in this study.

METHODS

Participants were asked to complete ten consecutive thoracic spine manipulations on an instrumented manikin. Peak force, preload force, time to peak force, time to peak force variability, peak force variability, rate of force production and unloading time were compared between groups. Hand-body delay obtained by calculating the temporal lag between the onset of unloading and the onset of peak force application was also compared between groups.

RESULTS

No group difference was observed for the peak force, peak force variability and preload force variables. However, group differences were present for variables like time to peak force, time to peak force variability, rate of force production, unloading time and hand-body delay.

CONCLUSION

This study demonstrates clear differences between groups of subjects with different levels of expertise in thoracic spine manipulation. This study also demonstrates the usefulness of a simple, instrumented manikin to analyze spinal manipulation and identify important parameters related to expertise.

Temporal modulations of agonist and antagonist muscle activities accompanying improved performance of ballistic movements

Although many studies have examined performance improvements of ballistic movement through practice, it is still unclear how performance advances while maintaining maximum velocity, and how the accompanying triphasic electromyographic (EMG) activity is modified. The present study focused on the changes in triphasic EMG activity, i.e., the first agonist burst (AG1), the second agonist burst (AG2), and the antagonist burst (ANT), that accompanied decreases in movement time and error. Twelve healthy volunteers performed 100 ballistic wrist flexion movements in ten 10-trial sessions under the instruction to "maintain maximum velocity throughout the experiment and to stop the limb at the target as fast and accurately as possible". Kinematic parameters (position and velocity) and triphasic EMG activities from the agonist (flexor carpi radialis) and antagonist (extensor carpi radialis) muscles were recorded. Comparison of the results obtained from the first and the last 10 trials, revealed that movement time, movement error, and variability of amplitudes reduced with practice, and that maximum velocity and time to maximum velocity remained constant. EMG activities showed that AG1 and AG2 durations were reduced, whereas ANT duration did not change. Additionally, ANT and AG2 latencies were reduced. Integrated EMG of AG1 was significantly reduced as well. Analysis of the alpha angle (an index of the rate of recruitment of the motoneurons) showed that there was no change in either AG1 or AG2. Correlation analysis of alpha angles between these two bursts further revealed that the close relationship of AG1 and AG2 was kept constant through practice. These findings led to the conclusion that performance improvement in ballistic movement is mainly due to the temporal modulations of agonist and antagonist muscle activities when maximum velocity is kept constant. Presumably, a specific strategy is consistently applied during practice.

EMG remains fractionated in Parkinson's disease, despite practice-related improvements in performance

OBJECTIVE

We studied the ability of patients with Parkinson's disease to improve their performance in a motor task requiring both speed and accuracy in the execution of elbow flexion movements. Our goal was to investigate the changes in electromyographic activity associated with the changes in movement performance.

METHODS

Eleven patients on anti-Parkinsonian medication were tested. The patients were selected for being bradykinetic, having little or no resting tremor or dyskinesias, and being in stages II or III of the Hoehn and Yahr rating scale.

RESULTS

The untrained patients displayed multiple bursts of agonist activity, characteristic of Parkinsonian EMG recordings. All patients improved their performance by increasing peak velocity while maintaining movement accuracy within strict boundaries. With practice, the patients' performance changed in a manner similar to that which has been previously observed for performance curves in neurologically normal subjects. As movement duration decreased (i.e. peak velocity increased), we observed a slight decrease in the number of agonist bursts and an increase in the average burst duration. However, the patients continued to generate a fractionated, multi-burst agonist pattern.

CONCLUSIONS

We conclude that Parkinsonian patients benefit from practice by improving their performance but remain fundamentally impaired in the generation of muscle activation patterns. This study has shown that the generation of fractionated, multiple short bursts of EMG activity that is characteristic of movements made by Parkinsonian patients is not normalized by practice.