Practice Schedule And The Learning Of Motor Skills In Children And Adults: Teaching Implications

Understanding how motor skills are learned influences how one teaches effective motor skill attainment. Educators must ask, “Does repetitive practice of the same task make for better performance or does contextual variability (random practice) offer some benefit when learning motor skills?” Studies on the effects of Contextual Interference may provide some insight. Contextual interference (CI) studies typically use simple tasks involving movements already acquired by adults, which may account for random practice benefits. In contrast, children do not consistently demonstrate CI effects, as tasks usually require acquisition of a new movement pattern. In this experiment, adults and children ((8-10 yrs old) threw a Frisbee to targets for 54 trials under random or blocked conditions. Having had considerable throwing experience with other throwing objects, adults were expected to benefit from random practice. For children, a blocked practice advantage was predicted as it provides for devising and stabilizing a suitable movement pattern. Retention/retraining trials were administered 30 minutes after acquisition and seven days later. Two transfer tests were given after the delayed retention test: (a) same throwing object/different target distances (SODT), which required re-scaling the practiced movement, and (b) different throwing object (ropeball)/same target distances (DOST) which required a new movement pattern. Throwing accuracy was measured by absolute error from the target. Both age groups showed a blocked practice benefit on retention and SODT transfer tests. Findings from this experiment suggest that task variables and stage of learning are important determinants of CI effects and thus should influence how we teach motor skill attainment

Influence of Biomechanical Constraints on Endpoint Control, Interlimb Coordination and Learning

A number of movements produced in everyday life require not only coordination of joints within a limb, but also coordination between one or more limbs. The aim of this dissertation was to examine the influence of biomechanical constraints on intralimb coordination, interlimb coordination, and learning. Experiment 1 sought to determine if principles of the Leading Joint Hypothesis, when applied to a multijoint bimanual coordination task, could provide insight into the contribution of intralimb dynamics to interlimb coordination. Participants repetitively traced ellipse templates in an asymmetrical coordination pattern (i.e. both limbs moving counter-clockwise). Kinematic data of the upper limbs were recorded with a VICON camera system. Ellipse templates were oriented either tilted right or tilted left; yielding a total of four left arm-right arm leading joint combinations. The findings indicated that stability of interlimb coordination patterns were found to be influenced by whether arm movements were produced with similar or different leading joints. Bimanual asymmetric ellipse-tracing produced with similar leading joints were more stable than patterns produced with different leading joints. For example, asymmetric coordination patterns produced with similar leading joints exhibited less transient behavior than coordination patterns produced with different leading joints (p < .01). Experiment 2 expanded on these findings by employing a similar task and incorporating a learning component to assess how intralimb dynamics are tuned with practice of a novel coordination pattern. Participants were randomly assigned to one of three groups. One group practiced tracing a pair of ellipse templates that were oriented in such a way that required similar leading joints while the other two groups practiced tracing ellipse templates that required different leading joints. Early in practice, the group learning the coordination pattern with similar leading joints exhibited greater interlimb stability than the two groups learning with different leading joints. However, following two days of practice, performance of the groups learning with different leading joints improved to match that of the group learning with similar leading joints. The findings suggest that initial biomechanical constraints can be overcome with practice, resulting in similar performance regardless of whether being produced with similar or different leading joints

Impaired Postural Control Reduces Sit-to-Stand-to-Sit Performance in Individuals with Chronic Obstructive Pulmonary Disease

Abstract Background: Functional activities, such as the sit-to-stand-to-sit (STSTS) task, are often impaired in individuals with chronic obstructive pulmonary disease (COPD). The STSTS task places a high demand on the postural control system, which has been shown to be impaired in individuals with COPD. It remains unknown whether postural control deficits contribute to the decreased STSTS performance in individuals with COPD. Methods: Center of pressure displacement was determined in 18 individuals with COPD and 18 age/gender-matched controls during five consecutive STSTS movements with vision occluded. The total duration, as well as the duration of each sit, sit-to-stand, stand and stand-to-sit phase was recorded. Results: Individuals with COPD needed significantly more time to perform five consecutive STSTS movements compared to healthy controls (1966 vs. 1364 seconds, respectively; p = 0.001). The COPD group exhibited a significantly longer stand phase (p = 0.028) and stand-to-sit phase (p = 0.001) compared to the control group. In contrast, the duration of the sit phase (p = 0.766) and sit-to-stand phase (p = 0.999) was not different between groups. Conclusions: Compared to healthy individuals, individuals with COPD needed significantly more time to complete those phases of the STSTS task that require the greatest postural control. These findings support the proposition that suboptimal postural control is an important contributor to the decreased STSTS performance in individuals with COPD

Training BIG to move faster: the application of the speed–amplitude relation as a rehabilitation strategy for people with Parkinson’s disease

We have used the phenomenon that speed increases with movement amplitude as a rehabilitation strategy. We tested the hypothesis that the generalized training of amplitude in the limb motor system may reduce bradykinesia and hypokinesia in the upper and lower limbs in subjects with Parkinson’s disease (PD) across disease severity (Stage I, n=6; Stage II, n=7; Stage III, n=5). While studies have separately examined the relationship of amplitude to speed in reaching and gait, the same study has not reported the relationship for both limb systems. Moreover, the rehabilitation intervention, Training BIG, is unique in that it applies well-established treatment concepts from a proven treatment for the speech motor system in PD [Lee Silverman Voice Treatment (LSVT®)] to the limb motor system. Subjects (n=18) participated in intense practice (1-h sessions/4× week/4 weeks) of large amplitude movements involving the whole body (i.e., head, arm, trunk, and leg) while focusing on the sensory awareness of “movement bigness.” Testing procedures were designed to demonstrate the transfer of generalized amplitude practice to speed improvements during functional “untrained” tasks in “uncued” conditions with blinded testers. After therapy, the subjects significantly increased their speed of reaching and gait for the preferred speed condition. This effect was greater when the severity of the disease was less. The results support further application and efficacy studies of Training BIG. Amplitude-based behavioral intervention in people with PD appears to be a simple target that may be applied in different contexts for multiple tasks and results in improved speed–amplitude scaling relations across the upper and lower limbs

Information-theoretic Sensorimotor Foundations of Fitts' Law

© 2019 ACM. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published is accessible via https://doi.org/10.1145/3290607.3313053We propose a novel, biologically plausible cost/fitness function for sensorimotor control, formalized with the information-theoretic principle of empowerment, a task-independent universal utility. Empowerment captures uncertainty in the perception-action loop of different nature (e.g. noise, delays, etc.) in a single quantity. We present the formalism in a Fitts' law type goal-directed arm movement task and suggest that empowerment is one potential underlying determinant of movement trajectory planning in the presence of signal-dependent sensorimotor noise. Simulation results demonstrate the temporal relation of empowerment and various plausible control strategies for this specific task

Coordination Control of a Dual-Arm Exoskeleton Robot Using Human Impedance Transfer Skills

This paper has developed a coordination control method for a dual-arm exoskeleton robot based on human impedance transfer skills, where the left (master) robot arm extracts the human limb impedance stiffness and position profiles, and then transfers the information to the right (slave) arm of the exoskeleton. A computationally efficient model of the arm endpoint stiffness behavior is developed and a co-contraction index is defined using muscular activities of a dominant antagonistic muscle pair. A reference command consisting of the stiffness and position profiles of the operator is computed and realized by one robot in real-time. Considering the dynamics uncertainties of the robotic exoskeleton, an adaptive-robust impedance controller in task space is proposed to drive the slave arm tracking the desired trajectories with convergent errors. To verify the robustness of the developed approach, a study of combining adaptive control and human impedance transfer control under the presence of unknown interactive forces is conducted. The experimental results of this paper suggest that the proposed control method enables the subjects to execute a coordination control task on a dual-arm exoskeleton robot by transferring the stiffness from the human arm to the slave robot arm, which turns out to be effective

Theories for Skilled Limb Movements .

Some of the theories that have been advanced to perform skilled limb movements are reviewed in this paper. The aspects discussed in brief include alpha-gamma control, choice of control variables in limb movements, equilibrium point hypotheses, experimental observations from simple movement studies and explanations proposed, in particular the dual strategy hypothesis. The single mechanical degree-of-freedom movements may be controlled by one of two strategies: a speed-insensitive strategy or a speed-sensitive strategy. The term strategy implies a set of rules which specify in terms of task variables and subject instructions how to choose the excitation signal, the controlling signal at the alpha motoneuron level. The two strategies differ in that speed-insensitive strategy is a result of duration modulation of the excitation pulse, whereas the speed-sensitive strategy is a result from amplitude modulation. Finally, the problem of multi-degrees of freedom movements and the role of higher motor control centres are discussed in brief

Robotic therapy for chronic stroke: general recovery of impairment or improved task-specific skill?

VS. Robotic therapy for chronic stroke: general recovery of impairment or improved task-specific skill