Permanent deficits in handgrip strength and running speed performance in low birth weight children

Objective: The main goal of this study was to verify the influence of low birth weight (LBW) on the physical fitness of children aged 710 years. The comparisons were subsequently adjusted for chronological age, gender, physical activity (PA), and body composition. Methods: A total of 356 children of both genders born in Vitoria de Santo Antao (Northeast of Brazil) were divided into two groups according to their birth weight (LBW < 2.500 g, n = 100, and normal birth weight, NBW = 3.000 g and = 3.999 g, n = 256). Body composition measurements included body weight, height, body mass index, triceps, and subscapular skinfolds, and body fat percentage (%BF). PA was assessed by a questionnaire. Physical fitness was assessed by handgrip strength, muscle endurance, explosive power, flexibility, agility, maximal oxygen consumption (VO2max), and running speed. Results: LBW children were shorter, lighter, had lower fat-free mass, muscle strength, and running speed but a higher VO2max than the NBW group. The differences in body weight (P = 0.507), height (P = 0.177), fat-free mass (P = 0.374), and VO2max (P = 0.312) disappeared when adjusted for covariates. The differences in right and left handgrip strength (P < 0.01) and running speed (P < 0.01) remained significant even when controlled for age, gender, height, fat-free mass, and PA. Conclusion: This combined analysis suggests that LBW alone can be not considered as a biological determinant of growth, body composition, or physical fitness in children, but is a predictor of muscle strength and running speed. Am. J. Hum. Biol., 2013. (c) 2012 Wiley Periodicals, Inc.