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Birth weight and physical ability in 5- to 8-yr-old healthy children born prematurely


Medicine & Science in Sports & Exercise: September 1997 - Volume 29 - Issue 9 - p 1124-1130
Clinical Sciences: Clinical Investigations

Recent advances in perinatal care have resulted in increased survival rates of extremely small and immature newborns. This has resulted in some neurodevelopmental impairment. The purpose of this study was to quantitatively evaluate and compare neuromuscular performance in children born prematurely at various levels of subnormal birth weight (BW). Subjects were 5- to 8-yr-old children born prematurely at different levels of subnormal BW (535-1760g,N = 22, PM), and age-matched controls born at full term (>2500g,N = 15, CON). None of the subjects had any clinically defined neuromuscular disabilities. Body mass (BM) of PM was lower than that of CON(18.3 ± 2.7 vs 21.7 ± 3.8 kg) with no difference in height or sum of 4 skinfolds. Peak mechanical power output determined with a 15-s modified Wingate Anaerobic Test and corrected for BM was lower (P = 0.07) in PM than in CON (5.11 ± 1.07 vs 5.94 ± 1.00 W·kg-1). This was especially noticeable in children born at extremely low BW (ELBW, <1000g, 4.49 ± 1.04 W·kg-1,P<0.01). Peak power, determined in a force-plate vertical jump, corrected for BM was lower in PM vs CON (25.5 ± 5.4 vs 30.8 ± 5.2 W·kg-1, respectively P = 0.01), especially in the ELBW group (20.0 ± 5.5 W·kg-1). Similarly, the elapsed time between peak velocity and actual jump take-off was longer in PM than in CON (41.2 ± 9.4 vs 35.8 ± 5.8 ms, respectively, P = 0.04). No differences were observed in peak force. The results suggest that performance deficiencies of prematurely-born children may be a result of inferior inter-muscular coordination. The precise neuromotor factors responsible for this should be identified by future research.

Ribstein Center for Research and Sport Medicine Sciences, Wingate Institute, Netanya, ISRAEL; Neonatal Intensive Care U, Meir General Hospital, Kfar Saba, ISRAEL; Children's Exercise and Nutrition Center, McMaster University and Department of Pediatrics, Chedoke-McMaster Hospitals, Hamilton, Ontario, CANADA

Submitted for publication November 1996.

Accepted for publication May 1997.

We thank the subjects and their parents for their cooperation and willingness to take part in all the tests. We thank Michal Cohen-Schienovitz and Nitza Shinker for their devoted technical help.

This study was supported by the Israeli Sports Authority.

Address for correspondence: Bareket Falk, Ph.D., Ribstein Center for Research and Sport Medicine Sciences, Wingate Institute, Netanya 42902, Israel. E-mail:

©1997The American College of Sports Medicine