8

Motor Learning

Optimizing Conditions for Teaching and Learning Movement

Joyce R. Maring, PT, DPT, EdD and Susan Joy Leach, PT, PhD, NCS, CEEAA

CHAPTER OBJECTIVES

After reading this chapter, the reader will be prepared to:

• Describe the influence of motor control theories on the application of teaching and learning motor skills.
  
• Identify the stages of motor learning and the focus of each stage of learning in skill development.
  
• Analyze the role of attention in learning a new motor skill.
  
• Classify motor skills according to existing taxonomies.
  
• Describe the conditions and variables that influence how motor tasks are processed.
  
• Relate the conditions of prepractice and practice to outcomes in motor performance and motor learning.
  
• Consider the role of providing feedback in effectively teaching motor skill acquisition.
  
• Apply the principles of motor learning to clinical case scenarios to enhance teaching and learning effectiveness and patient/client performance.

In this chapter, we transition to the role of the therapist as a specialist in the movement system and therefore as movement educator. Therapists teach patients and others how to best acquire or regain motor skills required for maximal participation in all aspects of life. Similar to education in the classroom, teaching motor skills requires the therapist to design environments and conditions that encourage learning through active engagement and practice. In this chapter, we explore our role as movement educators. We describe how theories of motor control and motor learning inform practice. We examine various types of movement, task characteristics, and movement taxonomies. Humans as information processors is discussed and linked to concepts such as attention, interference, response alternatives, and accuracy demands, all essential to teaching and learning about movement. We examine conditions of practice, types of practice, and practice schedules, and how each can be used to optimize learning given the individual, the task, and the environment. Various forms of feedback are introduced and linked to effective learning. Finally, the chapter ends with a discussion of differences across the lifespan.

ROLE OF THEORY IN PRACTICE

Physical therapists are considered movement specialists. We analyze movement and movement dysfunction and then work with individuals to establish or re-establish optimal movements that lead to improved function and quality of life. Therefore, we serve as movement educators and need to effectively apply to clinical practice all of the principles of teaching-learning discussed in this book. We need to know what strategies, patterns, and types of practice will lead to the most effective motor learning in the populations we serve. What are those internal and external processes associated with practice and experience that contribute to motor learning or the acquisition of a motor skill?

Theories are sets of assumptions that we use to explain and predict behaviors. They provide frameworks for our intervention strategies and therapeutic approaches. Theories drive practice. Theoretical assumptions should not be randomly selected, but rather should be chosen as a result of careful and systematic testing and observations. As the systematic testing of assumptions in motor control and learning progressed, theories also evolved; this evolution has had a tremendous impact on the way we practice physical therapy. Just as your assumptions about culture influence your practice, the conjectures that you have about how we control movement influence how you intervene when working with an individual with movement dysfunction. Physical and occupational therapists have been referred to as applied motor control physiologists.1 That is why we need to include a brief discussion to meet the objectives related to motor learning or teaching patients new motor skills (an in-depth discussion of current motor control theories is beyond the objectives of this chapter).

Motor Control Theories

Historical motor control theories were based on assumptions of hierarchical and stimulus-response control of movement.² Sensory input dictates motor output. According to this theory of how we control our movements, if we are trying to improve the way someone walks, our best treatment strategy is to provide him or her with optimal sensory feedback that will, in turn, result in a better walking pattern. So, for example, if we are working with a child with cerebral palsy who uses excessive hip adduction and internal rotation and who is having difficulty getting full hip extension when walking, we might facilitate the child’s movements by giving tactile and proprioceptive input (ie, placing your hands on) to the gluteus medius and gluteus maximus muscles to facilitate hip extension and inhibit the adduction. Through the lens of these historical theories, therapists viewed movement dysfunction secondary to a neurologic lesion as an interruption of the ability of the higher levels to inhibit or control the lower-level primitive reflexes. In this context, our primary role as therapists was to use sensory feedback, such as facilitation and inhibition, to help the higher centers of the nervous system recover control over the lower centers.

Systems Theory and Beyond

Today, we have moved beyond stimulus-response and hierarchical control theories of movement control. Current motor control theories suggest that there are many complex factors that may influence the control and learning or relearning of movements. Russian scientist Bernstein described much of the early work in this area. He hypothesized that movement control was distributed among interacting systems and that all of these interactions must be considered in accounting for the control of movement. This is referred to as a distributed model of motor control.³ Today, that model continues to evolve and expand to take into account the many parameters of movement that must be considered. For example, motor control theories must explain factors such as initiation of movement, the pattern and timing of muscle recruitment, and the influence of environmental variations and task requirements on movement production. That is a lot to consider!

Shumway-Cook and Woollacott4 and others describe the dynamic systems model, in which movement emerges from the interaction of the following 3 primary factors: the environment, the task, and the individual. Each of these factors has the ability to both constrain and enable movement possibilities. Focusing on only one factor, such as the processes within an individual, excludes the contribution of the demands of the task and environment to the control and production of movement. As physical therapists, we are well trained to identify the movements that we want to facilitate and we can describe in detail the musculoskeletal components required to produce those movements. But that is only one piece of the puzzle, and, to be effective teachers of movement and motor skill, we need to pay attention to the attributes of the tasks that we are asking the individual to learn and the environmental contexts in which those tasks will be performed. Movements that may serve an individual well in one environment may need to shift in response to a change in a key parameter. For example, imagine that you were walking on a treadmill. As the velocity increased, your gait pattern would dramatically change as you were transitioning from a walk to a run to meet the increasing velocity demands.

This evolving motor control theory impacts how we, as therapists, examine and intervene with patients who are learning or relearning how to accomplish functional skills. Theory impacts practice! Current theories of motor control and learning stress the organization of practice and movements around a behavioral goal so that retraining becomes task-oriented.⁴ All practice sessions should be centered on an established goal or task that is valued by the participant.⁵ As you know by now, this is a concept that is important to all teaching-learning strategies. The added purpose of a goal-directed task enhances motor learning in all contexts.⁶

Given the earlier example, evolving theories require the therapist to consider the goal of the task (eg, independent and safe ambulation in a specific environment) in addition to the process of ambulating. Potentially, the therapist can think of ways to change the task or to modify the environment to improve the pattern of movement and, therefore, the outcome. This allows the therapist and patient to focus not only on individual factors, such as strength and range of motion, but also on task and environmental factors when designing an intervention intended to achieve movement goals.

Through practice, the acquisition of skilled behavior moves through the following stages of learning: cognitive, associative, and autonomous (Table 8-1). Fitts and Posner⁷ described these 3 stages of learning quite some time ago, and they still provide a useful framework today.

Cognitive Stage

At this stage of learning, the individual is seeking to understand what it takes to perform the skill and to develop a cognitive map. The learner will perform a series of trials and discard the strategies that are not successful. He or she usually relies heavily on feedback (especially visual cues) and practices best in a stable or closed environment. A stable or closed environment is defined as a predictable environment in which everything is the same each and every time a person does the task.

For example, you may be working with a patient who had a recent amputation and has a new prosthetic limb. Initially, he or she may want to practice walking in the parallel bars (a stable and closed environment) and receive a lot of feedback. The patient may experiment with shifting his or her weight in different directions over the prosthetic limb and moving the prosthetic limb in all planes of motion. A mirror could be set up to provide visual input.

As a therapist working with a patient in the cognitive stage of motor learning you may want to provide the following:

• A safe closed environment
  
• Opportunities for trial-and-error practice of the movement
  
• Opportunities for feedback (particularly visual cues)

Associative Stage

This is the middle stage of learning a new motor task. The movement begins to look more organized and coordinated than it did during the cognitive stage, and there is greater consistency, fewer errors, and fewer extra movements except when the patient is distracted or asked to perform more than one task at a time. At this stage of practice, he or she is able to successfully walk with the prosthetic limb in a closed environment (ie, within the parallel bars). The individual reliably moves in all directions as long as he or she is able to concentrate on what he or she is doing. The patient tells you that he or she is beginning to get the feel of it. Errors in gait pattern and problems with balancing with the new limb emerge when he or she is unexpectedly distracted or if he or she has to do too many things at once, such as answer a question and turn a corner at the same time. As a therapist working with a patient/client in the associative stage of learning, you may do the following:

This final stage generally happens after much practice and the task requires little cognitive effort at this point. The individual can now concentrate on other demands at the same time as performing the task and can readily perform the skill or task in a predictable or a dynamic and changing environment. Research in cognitive neuroscience supports that performing a skill in the autonomous stage is associated with less cortical effort, especially for the parts of the brain that have to make decisions.8

• Movement taxonomy along 3 continua9
  
• Open vs closed tasks or skills
  
• Discrete vs continuous tasks or skills
  
• Stability vs mobility tasks or skills

Movement Taxonomy

Gentile⁹ created a taxonomy that looked at movement along 3 continua simultaneously:

1. Stationary vs variable environment
   
2. Stable vs dynamic body
   
3. No manipulation vs maximum manipulation demands.

Figure 8-1 illustrates Gentile’s Taxonomy of Tasks.¹⁰

Open vs Closed Tasks or Skills

This classification considers the interaction of the task and the environment. Closed skills or tasks are characterized by fixed environmental demands and can be produced with minimal variations each time. Open tasks occur under variable conditions, requiring instantaneous adaptation. Most tasks fall along a continuum of open or closed, depending on the role of the environment. Sometimes, we use the terms open and closed to refer to the environment itself. As noted earlier, the closed environment is stable and predictable, and the open environment is constantly changing. Table 8-2 describes the characteristics of open vs closed tasks or skills and provides examples of each.

Discrete vs Continuous Tasks or Skills

Intuitively, you know the type of skills required to perform a specific skill; for example, picking something up from the floor from a standing position is very different than the type of skill required to go for a walk. Tasks can be classified as discrete tasks, which have a recognizable beginning or end, vs a continuous skill, which does not have an inherent beginning and end. Table 8-2 describes the characteristics of discrete vs continuous tasks or skills and provides examples of each. Sometimes, a series of discrete movements can be performed in a sequence. We refer to these as serial movements, and they are composed of discrete movements strung together. Many activities of daily living are serial movements. For example, dressing in the morning requires a series of discrete tasks performed together.

As previously described in Gentile’s9 Taxonomy (stable vs dynamic body), movement requirements can vary depending on whether the base of support is in motion. Table 8-2 describes the characteristics of stability vs mobility tasks or skills and provides examples of each.

It Matters!

We have talked about how therapists need to consider the taxonomy of tasks and environments so that they can intentionally increase the complexity and demands of the task. This building process helps our patients to perform necessary skills at an autonomous level. Performing necessary skills autonomously means that they can be performed safely in real-life scenarios. The individual cannot only walk independently, but can also cross a street while monitoring other pedestrians and the color of the traffic light. Setting clinical goals in collaboration with the patient/client that adequately incorporate the practical realities of living and working in the community is a critical skill required of all therapists.

There is a significant body of evidence that we exert far more control over our responses than such a perspective would indicate. We are much more than a “black box” that receives input, which subsequently drives the output. There are a number of factors that influence what stimuli we attend to, how quickly we can filter the stimuli and select possible response options, and then how we implement the output we selected. Schmidt and Lee11 describe human beings as complex information processors. After the stimulus is received from the environment, we process it in a number of ways before acting upon it. As information processors, we do the following:

• Identify stimuli that we receive: As part of the identification process, we detect and recognize familiar patterns. Most responses require us to pick out meaningful patterns of features in the stimuli presented (eg,, how fast is that car travelling toward me?).
  
• Select a number of stimulus-response alternatives: We decide upon the possible options.
  
• Program a response based on the selection: This involves organizing and initiating a reaction.
  
• Produce a response at the level of the effector.

The point is, as an information processor, we have a lot of control over the stimuli we attend to and the subsequent responses we select. Those processes are influenced, however, by a number of factors. Understanding those factors assists us in being aware of their impact on the patients/clients we treat and, therefore, we can better assist them in selecting a response that leads to improved function.

Attention and Information Processing

We all have a limited potential for attention at any given moment. We may be bombarded by stimuli and sensory input, but it is not possible to attend to all of the input we receive. We do not, however, cut off the sensory input at the level of the receptors. Our nervous systems are picking up all of the sounds, sensations, visual inputs, and stimuli that surround us. The stimuli pass through some sort of attention filter and we decide which ones require our response.

One way to determine how much attention is being used is to calculate dual-task cost. Consider 2 tasks that you can measure separately, such as gait speed and a cognitive task such as saying the alphabet out loud and skipping every other letter. Both of these skills can be performed separately and then performed together. Any drop in performance in the dual-task condition over the single-task condition would be considered the dual-task cost. A drop in performance may be noted in either one or both of the tasks. A common test to determine someone’s risk for falls is the Timed Up and Go (TUG) test that simply measures the amount of time that it takes someone to transfer to a stand-up position, walk a short distance, turn, and sit back down again.12 It turns out that if you add a manual component such as carrying a cup of water (TUG manual) or a cognitive component such as counting backward by 3 (TUG cognitive), the amount of increased time required to complete the TUG task is a good measure of the cost of dividing one’s attention to perform dual tasks.¹³ The clinical implications of this finding are enormous, both for testing whether a person can safely navigate open environments where attention must be divided to maintain safety and in planning therapeutic interventions where distractors and additional tasks can be added incrementally. Think back again to the person with the prosthetic. How might you incrementally move from a closed and single-task environment to the demands of an open environment where attention has to be divided?

Given that attention plays such an important role in movement, can a therapist influence what the patient pays attention to and does focus of attention influence a patient’s performance? The focus of attention literature resoundingly says yes. In the focus of attention paradigm, the instructions or feedback provided to learners can have a significant impact on motor skill learning.14 An internal focus occurs when learners are directed to pay attention to their body movements, whereas an external focus occurs when learners are directed to pay attention to the effects of their movements on the environment or the outcome of their movements.¹⁵ Using a very simple example, a therapist may direct the patient’s focus of attention while moving from sit to stand by asking a patient to “push up with your hands” (internal focus) vs “push up from the armrests” (external focus). The point of the instruction is to focus the learner’s attention on the outcome of the movement rather than the movement itself.

Studies consistently demonstrate that an external focus of attention helps the participant to reliably learn the skill with more efficiency and effectiveness over less time. This is true whether the person is learning to stand on a stable or unstable surface^15,16 or learning a complex sport such as a slalom ski simulator task,¹⁷ pitching a golf ball at a target,¹⁸ hitting tennis strokes,^18–20 volleyball tennis serve,²¹ and a soccer pass.²¹ The results consistently show that an external focus is superior to an internal focus in terms of effective learning and performance. So, for ball games, it is usually better to focus the learner’s attention on the direction of a ball toward a target than to analyze how the arm or leg moved to contact the ball.

The effect of an external focus has also been studied in some patient populations. For example, an external focus of attention was shown to improve postural stability in a group of patients who had a stroke and experienced problems with balance.²² Participants who were instructed to shift their weight toward an external target next to their hip performed much better than those who were instructed on the weight-shifting movement itself. Using an external focus of attention during practice led to increased efficiency of movements and likely indicated decreased attention requirements, meaning that more automatic strategies were used during the task. (Remember the importance of getting to the automatic stage of learning!) Although findings related to the superiority of an external focus of attention are robust, physical therapists typically use instructions and feedback that are internally focused during stroke rehabilitation.^23,24 Researchers recorded and analyzed several gait training sessions and noticed that therapists asked the patient to pay attention to an internal process, such as pushing off with a leg or lifting a foot, in 67% of the directions. For patients having difficulty clearing a foot during gait or on the stairs, rather than asking the patient to lift his or her foot (internal focus), an external focus could be created by asking the patient to touch your hand with his or her knee or to touch a target on a step. Movement educators must consider the potential impact of our directions related to the person’s focus of attention while remembering that an external focus will generally help the person to learn faster and more efficiently; in other words, allow the movement to become more automatic.

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