MUSCLE POWER, SITTING UNSUPPORTED AND TRUNK ROTATION IN PRETERM INFANTS

Discrepancies between active and passive muscle power are often seen i n pre-term infants over the first year. Generally of a transient natur e, they are most obvious in the extensor muscles of the trunk where th ere is a high active muscle power relative to the passive component. W hile high active muscle power may not be a sign of cerebral palsy, it is our contention that it will impair functions such as unsupported si tting and the ability to rotate in this position. In this study, 20 fu ll-term and 37 healthy pie-term infants were assessed at the (correcte d) ages of 39 and 52 weeks for muscle power in the trunk, sitting unsu pported 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 ma jority of them could not rotate the trunk in this position. At 52 week s the majority of pre-term infants could sit without support, despite having higher active muscle power in the trunk. However this deviant m uscle 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 s hould be directed towards avoidance of extensor positions.