Document Detail

Longitudinal changes in muscle activity during infants' treadmill stepping.
MedLine Citation:
PMID:  22490560     Owner:  NLM     Status:  MEDLINE    
Previous research has described kinetic characteristics of treadmill steps in very stable steppers, in cross-sectional designs. In this study we examined, longitudinally, muscle activation patterns during treadmill stepping, without practice, in 12 healthy infants at 1, 6, and 12 mo of age. We assessed lateral gastrocnemius, tibialis anterior, rectus femoris, and biceps femoris as infants stepped on a treadmill during twelve 20-s trials. Infants showed clear changes in kinematics, such as increased step frequency, increased heel contact at touch down, and more flat-footed contact at midstance. Electromyographic data showed high variability in muscle states (combinations), with high prevalence of all muscles active initially, reducing with age. Agonist-antagonist muscle coactivation also decreased as age increased. Probability analyses showed that across step cycles, the likelihood a muscle was on at any point tended to be <50%; lateral gastrocnemius was the exception, showing an adultlike pattern of probability across ages. In summary, over time, healthy infants produce a wide variety of muscle activation combinations and timings when generating stepping patterns on a treadmill, even if some levels of muscle control arose with time. However, the kinematic stability improved much more clearly than the underlying kinetic strategies. We conclude that although innate control of limb movement improves as infants grow, explore, and acquire functional movement, stepping on a treadmill is a novel and unpracticed one. Hence, developing stable underlying neural activations will only arise as functional practice ensues, similarly to that observed for other functional movements in infancy.
Caroline Teulier; Jennifer K Sansom; Karin Muraszko; Beverly D Ulrich
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2012-04-04
Journal Detail:
Title:  Journal of neurophysiology     Volume:  108     ISSN:  1522-1598     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-08-02     Completed Date:  2013-01-10     Revised Date:  2013-08-14    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  853-62     Citation Subset:  IM    
Laboratoire Psychologie de la Perception, Centre National de la Recherche Scientifique, Université Paris Descartes, Paris, France.
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MeSH Terms
Biomechanics / physiology
Exercise Test
Foot / physiology
Leg / physiology
Longitudinal Studies
Muscle, Skeletal / physiology*
Walking / physiology*
Grant Support

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