Head size and motor performance in children born prematurely

PURPOSE: The objective of this study was to determine the relationship between head circumference (HC) and motor performance in 6- to 12-yr-old children born prematurely (PRE: birthweight > or = 1500 g, gestational age > or = 32 wk) and in children born at term (CON). METHODS: Thirty-three PRE and 21 CON without an apparent neurological deficit participated in this study. HC was measured on the day of testing and was rated as small HC (SHC, HC more than 1 SD below the 50th percentile of reference data) or as normal HC (NHC). Subjects were examined by an experienced neuropediatrician, and whole-body coordination was assessed by the Körper-Koordinationstest für Kinder (KTK). Peak exercise performance was determined by a Wingate test and an incremental cycling test to volitional fatigue. Net oxygen cost of cycling was measured during four different tasks lasting 5-7 min each. Subjects pedaled at an intensity corresponding to 30% and 60% of peak oxygen uptake ([OV0312]O(2peak)) at a cadence of 36 and 76 rpm, respectively. RESULTS: Prematures with SHC showed no statistically significant difference in their neurological examination and whole-body coordination compared with prematures with NHC. Wingate test performance and [OV0312]O(2peak) relative to body mass were similar among SHC, NHC, and CON. In SHC, but not in NHC and CON, net oxygen cost of cycling increased significantly (P > 0.05) when cadence was increased from 36 to 76 rpm. CONCLUSION: At the age of 6-12 yr, SHC have a higher oxygen cost of cycling in exercise tasks requiring high velocity, which might be explained-at least in part-by an impaired neural control of intra- and intermuscular coordination.