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Muscle power, sitting unsupported and trunk rotation in pre-term infants
L de Groot1, B Hopkins, B Touwen
1Faculty of Human Movement Sciences, Free University, Amsterdam, The Netherlands.
Insights
Pre-term infants often exhibit muscle power discrepancies, impacting trunk rotation and unsupported sitting. Early postural management is crucial to address these developmental challenges.
Area of Science:
- Developmental Pediatrics
- Motor Control
- Infant Physiology
Background:
- Pre-term infants frequently display transient discrepancies between active and passive muscle power.
- These differences are most pronounced in trunk extensor muscles, with high active power relative to passive components.
Purpose of the Study:
- To investigate muscle power development in pre-term infants.
- To assess the impact of muscle power on unsupported sitting and trunk rotation.
- To explore potential origins of muscle power deviance in pre-term infants.
Main Methods:
- Assessed 37 healthy pre-term and 20 full-term infants at corrected ages of 39 and 52 weeks.
- Evaluated trunk muscle power, unsupported sitting ability, and trunk rotation.
- Compared developmental milestones between pre-term and full-term infants.
Main Results:
- At 39 weeks, half of pre-term infants could not sit unsupported or rotate their trunks, unlike full-term infants.
- By 52 weeks, most pre-term infants could sit unsupported but still showed impaired trunk rotation.
- Pre-term infants demonstrated higher active trunk muscle power but retained deviant muscle function affecting rotation.
Conclusions:
- Deviant muscle power in pre-term infants can hinder functional skills like unsupported sitting and trunk rotation.
- Postural positioning in neonatal care may contribute to these muscle power deviations.
- Postural management strategies should focus on avoiding prolonged extensor positions to promote optimal motor development.
Abstract:
Discrepancies between active and passive muscle power are often seen in pre-term infants over the first year. Generally of a transient nature, they are most obvious in the extensor muscles of the trunk where there is a high active muscle power relative to the passive component. While high active muscle power may not be a sign of cerebral palsy, it is our contention that it will impair functions such as unsupported sitting and the ability to rotate in this position. In this study, 20 full-term and 37 healthy pre-term infants were assessed at the (corrected) ages of 39 and 52 weeks for muscle power in the trunk, sitting unsupported and rotation around the body axis while seated. At the age of 39 weeks, all full-term infants could sit without support. In contrast half of the pre-term infants could not sit without support and the majority of them could not rotate the trunk in this position. At 52 weeks the majority of pre-term infants could sit without support, despite having higher active muscle power in the trunk. However this deviant muscle power prevented rotatory movements of the trunk during sitting. The origin of this deviance may reside in the positioning to which pre-term infants are subjected after birth and thus postural management should be directed towards avoidance of extensor positions.