Motor Skill – What About You Need To Know

A motor skill is a learned ability to cause a predetermined movement outcome with maximum certainty. Motor learning is the relatively permanent change in the ability to perform a skill as a result of practice or experience. Performance is an act of executing a motor skill. The goal of motor skill is to optimize the ability to perform the skill at the rate of success, precision, and to reduce the energy consumption required for performance. Continuous practice of a specific motor skill will result in greatly improved performance.

Motor activity is represented by several behaviors (e.g., ambulation, grooming, rearing, sniffing) that involve coordinated involvement of sensory, motor, and associative processes. Motor activity testing often is performed in a novel environment using an automated detection system. Rodents may exhibit a substantial diurnal cyclicity in their level of spontaneous motor activity that must be considered when designing test batteries and interpreting data. Motor activity changes may result from CNS and/or PNS damage.

Types of motor skills

Gross motor skills require the use of large muscle groups to perform tasks like walking, balancing, and crawling. The skill required is not extensive and therefore are usually associated with continuous tasks. Much of the development of these skills occurs during early childhood. The performance level of gross motor skills remains unchanged after periods of non-use.^[rx] Gross motor skills can be further divided into two subgroups: oculomotor skills, such as running, jumping, sliding, and swimming; and object-control skills such as throwing, catching, and kicking. Motor skills are movements and actions of the muscles. Typically, they are categorized into eighteen groups:

• Fine motor skills – requires the use of smaller muscle groups to perform smaller movements with the wrists, hands, fingers, and feet, and toes. These tasks are precise in nature, like playing the piano, writing carefully, and blinking. Generally, there is a retention loss of fine motor skills over a period of non-use. Discrete tasks usually require more fine motor skills than gross motor skills.^[rx] Fine motor skills can become impaired. Some reasons for impairment could be an injury, illness, stroke, congenital deformities, cerebral palsy, and developmental disabilities. Problems with the brain, spinal cord, peripheral nerves, muscles, or joints can also have an effect on fine motor skills, and decrease control.^[rx]

Development

Motor skills develop in different parts of a body along three principles:

• Cephalocaudal – development from head to foot. The head develops earlier than the hand. Similarly, hand coordination develops before the coordination of the legs and feet. For example, an infant is able to follow something with their eyes before they can touch or grab it.^[rx]
• Proximodistal – the movement of limbs that are closer to the body develop before the parts that are further away, such as a baby learns to control the upper arm before the hands or fingers. Fine movements of the fingers are the last to develop in the body.^[rx]
• Gross to specific – a pattern in which larger muscle movements develop before finer movements. For example, a child only being able to pick up large objects, to then picking up an object that is small between the thumb and fingers. The earlier movements involve larger groups of muscles, but as the child grows finer movements become possible and specific things can be achieved.^[rx]

In children, a critical period for the acquisition of motor skills is preschool years (ages 3–5), as fundamental neuroanatomic structure shows significant development, elaboration, and myelination over the course of this period.^[rx] Many factors contribute to the rate at which children develop their motor skills. Unless afflicted with a severe disability, children are expected to develop a wide range of basic movement abilities and motor skills.^[rx] Motor development progresses in seven stages throughout an individual’s life: reflexive, rudimentary, fundamental, sports skill, growth and refinement, peak performance, and regression. Development is age-related but is not age-dependent. In regard to age, it is seen that typical developments are expected to attain gross motor skills used for postural control and vertical mobility by 5 years of age.^[rx]

There are six aspects of development:

• Qualitative – changes in movement-process results in changes in movement-outcome.
• Sequential – certain motor patterns precede others.
• Cumulative – current movements are built on previous ones.
• Directional – cephalocaudal or proximodistal
• Multifactorial – numerous-factors impact
• Individual – dependent on each person

In the childhood stages of development, gender differences can greatly influence motor skills. In the article “An Investigation of Age and Gender Differences in Preschool Children’s Specific Motor Skills”, girls scored significantly higher than boys on visual motor and graphomotor tasks. The results from this study suggest that girls attain manual dexterity earlier than boys.^[rx] Variability of results in the tests can be attributed towards the multiplicity of different assessment tools used.^[rx] Furthermore, gender differences in motor skills are seen to be affected by environmental factors. In essence, “parents and teachers often encourage girls to engage in [quiet] activities requiring fine motor skills, while they promote boys’ participation in dynamic movement actions”.^[rx] In the journal article “Gender Differences in Motor Skill Proficiency From Childhood to Adolescence” by Lisa Barrett, the evidence for gender-based motor skills is apparent. In general, boys are more skillful in object control and object manipulation skills. These tasks include throwing, kicking, and catching skills. These skills were tested and concluded that boys perform better with these tasks. There was no evidence for the difference in locomotor skill between the genders, but both are improved in the intervention of physical activity. Overall, the predominance of development was on balance skills (gross motor) in boys and manual skills (fine motor) in girls.^[rx]

Components of development

• Growth – increase in the size of the body or its parts as the individual progresses toward maturity (quantitative structural changes)
• Maturation – refers to qualitative changes that enable one to progress to higher levels of functioning; it is primarily innate
• Experience or learning – refers to factors within the environment that may alter or modify the appearance of various developmental characteristics through the process of learning
• Adaptation – refers to the complex interplay or interaction between forces within the individual (nature) and the environment (nurture)

Influences on development

• Stress and arousal – stress and anxiety is the result of an imbalance between demand and the capacity of the individual. In this context, arousal defines the amount of interest in the skill. The optimal performance level is moderate stress or arousal.^[rx] An example of an insufficient arousal state is an overqualified worker performing repetitive jobs. An example of an excessive stress level is an anxious pianist at a recital. The “Practice-Specificity-Based Model of Arousal” (Movahedi, 2007) holds that, for best and peak performances to occur, motor task performers need only to create an arousal level similar to the one they have experienced throughout training sessions. For peak performance, performers do not need to have high or low arousal levels. It is important that they create the same level of arousal throughout training sessions and competition. In other words, high levels of arousal can be beneficial if athletes experience such heightened levels of arousal during some consecutive training sessions. Similarly, low levels of arousal can be beneficial if athletes experience such low levels of arousal during some consecutive training sessions.^[rx]
• Fatigue – the deterioration of performance when a stressful task is continued for a long time, similar to the muscular fatigue experienced when exercising rapidly or over a long period. Fatigue is caused by over-arousal. Fatigue impacts an individual in many ways: perceptual changes in which visual acuity or awareness drops, slowing of performance (reaction times or movement speed), irregularity of timing, and disorganization of performance.
• Vigilance – the effect of the loss of vigilance is the same as fatigue, but is instead caused by a lack of arousal. Some tasks include actions that require little work and high attention.^[rx]
• Gender – gender plays an important role in the development of the child. Girls are more likely to be seen performing fine stationary visual motor skills, whereas boys predominantly exercise object-manipulation skills. While researching motor development in preschool-aged children, girls were more likely to be seen performing skills such as skipping, hopping, or skills with the use of hands only. Boys were seen to perform gross skills such as kicking or throwing a ball or swinging a bat. There are gender-specific differences in qualitative throwing performance, but not necessarily in quantitative throwing performance. Male and female athletes demonstrated similar movement patterns in humerus and forearm actions but differed in trunk, stepping, and backswing actions.

Stages of motor learning

Motor learning is a change, resulting from practice. It often involves improving the accuracy of movements both simple and complex as one’s environment changes. Motor learning is a relatively permanent skill as the capability to respond appropriately is acquired and retained.^[rx]

The stages of motor learning are the cognitive phase, the associative phase, and the autonomous phase.

• Cognitive phase – When a learner is new to a specific task, the primary thought process starts with, “What needs to be done?” Considerable cognitive activity is required so that the learner can determine appropriate strategies to adequately reflect the desired goal. Good strategies are retained and inefficient strategies are discarded. The performance is greatly improved in a short amount of time.
• Associative phase – The learner has determined the most effective way to do the task and starts to make subtle adjustments in performance. Improvements are more gradual and movements become more consistent. This phase can last for a long time. The skills in this phase are fluent, efficient, and aesthetically pleasing.
• Autonomous phase – This phase may take several months to years to reach. The phase is dubbed “autonomous” because the performer can now “automatically” complete the task without having to pay any attention to performing it. Examples include walking and talking or sight-reading while doing simple arithmetic.^[rx]

A motor unit consists of a single alpha motor neuron and all of the corresponding muscle fibers it innervates; all of these fibers will be of the same type (either fast twitch or slow-twitch).

When a motor unit is activated, all of its fibers contract. Groups of motor units often work together to coordinate the contractions of a single muscle. All of the motor units that subserve a single muscle are considered a motor unit pool.

The number of muscle fibers within each unit can vary. Thigh muscles, for example, can have a thousand fibers in each unit, eye muscles might have ten. In general, the number of muscle fibers innervated by a motor unit is a function of a muscle’s need for refined motion.

The smaller the motor unit, the more precise the action of the muscle. Muscles requiring more refined motion are innervated by motor units that synapse with fewer muscle fibers.

Motor unit recruitment is the progressive activation of a muscle by the successive recruitment of motor units to accomplish increasing gradations of contractile strength. The activation of more motor neurons will result in more muscle fibers being activated, and therefore a stronger muscle contraction.

Motor unit recruitment is a measure of how many motor neurons are activated in a particular muscle. It is therefore a measure of how many muscle fibers of that muscle are activated. The higher the recruitment, the stronger the muscle contraction will be.

Motor units are generally recruited in order of smallest to largest (from fewest fibers to most fibers) as contraction increases. This is known as Henneman’s Size Principle.