Course:KIN366/ConceptLibrary/LocomotorReflexes

Movement Experiences for Children
KIN 366
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Instructor:	Dr. Shannon S.D. Bredin
Email:	shannon.bredin@ubc.ca
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Locomotor Reflexes are one of the three types of reflexes vital in the motor development of infants in the first 2 years of life. They are reflexes that resemble later voluntary locomotor movements (Gabbard, 2008). Reflexes are defined as involuntary, subcortically controlled movements that are relatively stereotypical, in response to a specific stimulation (Kandel, Schwartz, & Jessell, 2000). They are the first forms of human movement. Reflexive behavior is important primarily for their role of stimulating the central nervous system (CNS) and muscles, and as a diagnostic tool to measure neurological integrity (Gabbard, 2008). Locomotor reflexes can be classified further into three types: swimming, crawling, and stepping.

Types of Locomotor Reflexes:

The three locomotor reflexes include swimming reflex, crawling reflex, and stepping reflex that are each elicited by a different stimulus and appear at different stages of development.

Swimming Reflex:

Stimulation and Response

The swimming reflex is elicited while holding the infant in a prone position underwater with either the head above or under the surface of the water (Gabbard, 2008). The infant reacts by exhibiting rhythmically flexor- extensor movements in the upper and lower limbs creating a kicking and paddling swimming motion (McGraw, 1939).

Onset and Disappearance

This reflex is demonstrated as early as the second week after birth and is noted to disappear by 4-6 months.

Purpose

Although an infant displays the swimming reflex, it does not mean they can necessarily swim. Simply, it serves as a survival mechanism if an infant is to be dropped in the water (Berk, 2012). A common involuntary response when an infant is submerged underwater is a bradycardiac response where the infant will hold their breath and open their eyes (Gabbard, 2008).

Crawling Reflex:

Stimulation and Response

The crawling reflex is triggered when a newborn is placed in a prone position on their stomach and alternative strokes are applied to the soles of both feet (Gabbard, 2008). The infant then responds by moving their legs and arms in a crawling motion (Gabbard, 2008).

Onset and Disappearance

This reflex’s onset is at birth and occurs till 4 months of age (Gabbard, 2008).

Purpose

The crawling reflex has been discussed to be a forerunner to future voluntary crawling and to promote the development of sufficient muscle tone (Gabbard, 2008).

False Crawling Reflex

When an infant is placed on their stomach, it will appear as if they are demonstrating the crawling reflex. However, almost one week later, the infant will lie flat and not exhibit the reflex. This is speculated as account of when an infant is in a curled position in the womb, it takes a natural instinctive position to protect themselves from asphyxiation when lying face down (Berk, 2012).

Stepping Reflex:

Stimulation and Response

The stepping reflex is stimulated by holding the infant upright while their feet touch a supporting surface (Gabbard, 2008). The infant will reflexively react to the pressure on their soles by lifting one foot after another simulating a stepping response (Berk, 2012).

Onset and Disappearance

This behaviour is seen as early as the end of the first week after birth to approximately two months of age; however it is variable due to the weight changes experienced at infancy (Berk, 2012).

Purpose

The stepping reflex has been noted to prepare the CNS to engage in voluntary walking. There are controversial discussions on the idea of “the disappearing reflex”, as erect locomotion does not appear till the latter months of the first year (Thelen et al.,1984). Other factors have been found to influence reflexive behavior, which are discussed in Exercising the Reflexes.

Exercising the Reflexes

Relationship between Physical Growth and Stepping Reflex

Thelen, Fisher, Ridley-Johnson (1984) played a significant role in discovering the behavioural consequences of rapid growth of early infancy (Thelen et al., 1984). They challenged the idea that stepping should not be considered a reflex, as its kinematic characteristics resembled those of kicking in the supine position (Thelen et al., 1984). However, the question still remained as to why one behavior disappeared and the other did not. Within the first few weeks and months after birth, infants gain a significant amount of body fat relative to muscle tissue (Fomon & Nelson, 2012). Consequently, due to the infant’s insufficient strength, they experience greater difficulty in the upright position to lift their heavier legs against gravity and thus, the stepping disappears (Thelen et al., 1984). While in the supine position, gravity supported the flexion of the legs, creating step-like movements (Thelen et al., 1984).

When looking at infants at 2,4, and 6 weeks of age, they determined that between the 2nd to 4th week, infants experience rapid weight gain and thus, decrease the amount of steps they take in the upright position (Thelen et al., 1984). The disuse of the reflex is therefore influenced by lack of muscle strength in the legs (Thelen et al., 1984). They furthered their research by performing two studies that manipulated the mass of the infant’s legs either by adding ankle weights or placing the legs under water. It was concluded that reflex stepping decreases with increased weight and stepping frequency increases when infants are submerged chest deep under water (Thelen et al., 1984). Water acts as a buoy for the legs, reducing the effects of the infant’s mass, thus creating a greater ease of stepping (Thelen et al., 1984).

In addition, when 6-7 month-old infants were supported over a treadmill, they presented alternating stepping movements similar to more mature walking, indicating that the underlying mechanism had not disappeared. Therefore, the stepping reflex expresses a pattern of presence- absence- presence rather than a full disappearance (Gabbard, 2008).

Relationship between Locomotion and the Stepping Reflex

Zelazo, Zelazo, & Kolb (1972) determined that infants who ‘practiced’ the stepping reflex daily, increased their stepping reflex and as well engaged in voluntary walking by a month earlier compared to infants who did not receive practice or who received passive movement in the supine position (Zelazo et al., 1972). The results demonstrated that the reflex is lost due to disuse and that with continued practice, the reflex becomes integrated in later independent locomotion (Thelen et al., 1984).

Transitioning from Involuntary to Voluntary Behaviours

Theoretical Outlooks

There has been substantial debate in regards to the relationship between early infancy reflexes to later voluntary movement (White, Livesey, & Hayes, 1993). Previous explanation includes that the maturational cortical centers inhibit the locomotor reflexes, such as the stepping reflex, as a result of motor tracts developing. As the cerebral cortex matures, most of these reflexes become inhibited to allow for the rise of voluntary motor behaviours (Gabbard, 2008). On the other hand, another perspective states that during the early stages of infancy, from birth to close to the first year, infants are reflex machines undergoing a constant process of neuromuscular functional maturation preparing them for voluntary behaviour (Gabbard, 2008).

Two viewpoints stand:

1) Traditional: Neonatal reflexes are independent of voluntary control and disappear (Gabbard, 2008).
2) Contemporary: Neonatal reflexes contribute to the emergence of later voluntary movement in which they are not lost but rather are inhibited and integrated into controlled behavior (Gabbard, 2008).

Traditional Theory

McGraw's Theory of Development

McGraw’s Theory of Development takes on the more traditional view of neonatal reflexes. In order for progression to voluntary controlled behavior, early reflexes, primarily locomotor reflexes, must be inhibited by the CNS- known as motor interference (Haywood & Getchell, 2014). This is believed because of the time lag seen between involuntary responses and the emergence of voluntary behavior; therefore suggesting there is no continuity and no direct link between the two (White, Livesey,& Hayes, 1993). For instance, the crawling reflex disappears by four months, while voluntary crawling is not seen till the sixth or seventh month (Gabbard, 2008).

The theoretical framework for McGraw places an emphasis on neuromaturational model of motor development, in particular the increasing role of the cerebral cortex (Heriza, 1991). She discussed four periods of neural maturation:

1) A period of reflexive behavior representing the function of lower centers of the CNS (Heriza, 1991).
2) A period of decline in overt expression of reflexes reflecting cortical inhibition of the functioning of lower centers (Heriza, 1991).
3) A period of cortical control over function as indicated by the deliberate or voluntary quality of overt activity (Heriza, 1991).
4) A period of integration of the various neural centers involved in function as evidence by smooth movements (Heriza, 1991).

Gessell’s Maturational Theory

Gesell’s Maturational Theory states that development is due to solely inherited factors and biological variables and that environmental stimulation serves little influence (Heriza, 1991). Development is assumed to progress in a sequential manner that is consistent among all individuals but rate of development is dependent on the infant’s hereditary background. This theory is contended by more contemporary theories suggesting that early development sequence is not fixed and heredity is not the only contributing factor (Gabbard, 2008).

Contemporary Theory

Dynamics Systems Theory

Dynamic systems theory encapsulates the interplay between the infant’s CNS, biomechanical, psychological, and social environments to explain movement changes (Heriza,1991). This theory supports the continuity between specific reflexive movement and voluntary movements and that reflexes are the building blocks for future volitional movements (Berk, 2012). For instance, as described earlier, Thelen and colleagues (1984) findings showed the stepping reflex potentially regresses as account of body size and composition changes not because of the central processes responsible of generating motor patterns (Thelen et al., 1984). Therefore, strength is the limiting factor not the loss of the reflex. As well as, Zelazo’s and colleagues’ (1972) findings, was a prime example that early reflex movements form the foundation for later voluntary movements as earlier voluntary walking is detected when the stepping reflex is “practiced” daily (Zelazo et al., 1972; White, Livesey,& Hayes, 1993).

Taken together, numerous individual factors play a role in the integration of reflexes and the onset of voluntary movement that are not only dependent on the maturation of the CNS.

Practical Applications

Clinical Applications

Reflexes are vital diagnostic indicators in the early months of infancy to assess neurological maturity (White, Livesey, & Hayes, 1993). Pediatricians can elicit the neonatal and infantile reflexes to measure the neurological function of the child. Considering reflexes occur within a predicable age ranges, pediatricians can identify any neurological impairment. Impairments can be indicated by the absence of a reflex, prolonged persistence of a reflex beyond the age that it should have disappeared, presence of unequal bilateral reflex response, and/or uneven strength characteristics of a reflex (Gabbard, 2008; White, Livesey, & Hayes,1993). To perform an assessment on neonatal behaviour, the Apgar Scale and Brazelton can be used.

Guidance Considerations

Parents, guardians, and caregivers should understand that motor development during infancy is essential for the emergence of later voluntary movements. They should facilitate an environment that provides their infant the opportunity to be mobile, whether it is self-initiated or guided. As a result, caregivers should maximize activity time and limit restraint time to foster infantile movements. Locomotor reflexes serve as a fundamental precursor for voluntary movements, importantly erect locomotion. If parents can help exercise the reflexes, it will further promote the maturation of the CNS, promote greater frequency of the reflex, and respectively, potentially cause for an earlier onset of voluntary movements. When exercising the reflexes, make sure there is an attentive parent to be mindful of their infant’s behavior, in particular while their babies are immersed under water to prevent drowning and as well swallowing too much water (Berk, 2012).

References

Berk, L.E. (2012) Infants and Children: Prenatal Through Middle Childhood. Boston, MA: Pearson Education.

Fomon, S. J., & Nelson, S. E. (2002). Body Composition of the Male and Female Reference Infants 1. Annual review of nutrition, 22(1), 1-17.

Gabbard C.P. (2008). Lifelong Motor Development, 5th ed. San Francisco, CA: Pearson Benjamin Cummings.

Haywood, K., & Getchell, N. (2014). Life Span Motor Development. Champaign, IL: Human Kinetics.

Heriza, C. (1991). Motor development: traditional and contemporary theories. In Contemporary management of motor control problems: proceedings of the II Step Conference. Alexandria, VA: Foundation for Physical Therapy.

Kandel E.R., Schwartz J.H., Jessell T.M. (2000). Principles of Neural Science, 4th ed. New York, NY: McGraw-Hill.

McGraw, M. B. (1939). Swimming behavior of the human infant. The Journal of Pediatrics, 15(4), 485-490.

Thelen, E. (1986). Treadmill-Elicited Stepping in Seven-Month-Old Infants. Child Development, 57(6), 1489-1506.

Thelen, E, Fisher D.M., Ridley-Johnson, R. (1984). The relationship between physical growth and a newborn reflex. Infant Behaviour and Development, 7(4), 479-493.

White, F., Livesey, D., Hayes, B. (2012). Development Psychology: From Infancy to Adulthood. Sydney, AU: Pearson Australia.

Zelazo, P. R., Zelazo, N. A., & Kolb, S. (1972). " Walking" in the Newborn. Science, 176(4032), 314-315.