Exercise, nutrition, and anthropometry of bone development in term and preterm infants

Ita Litmanovitz*, Alon Eliakim

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

Abstract

The physiology of bone mass accretion in the early postnatal life has been studied extensively due to the development of reliable, precise, and noninvasive methods for bone mass assessments. Most of the studies address bone development in very low birth weight preterm infants. Given that the period of greatest bone mineral accretion in utero occurs during the last trimester of pregnancy and that it is very difficult to match bone requirements in the postnatal extra-uterine environment, metabolic bone disease remains relatively common in preterm infants. At birth, both bone mineral density measured by dual X-ray (DEXA) absorptiometry and bone strength measured by quantitative ultrasound measurements of bone speed of sound (SOS) were found to be significantly lower in preterm compared to infants born at term, with a strong correlation between tibial SOS and gestational age. Moreover, longitudinal studies demonstrated a decrease in bone mineralization by DEXA and in bone strength determined by bone SOS during the 1st weeks of post-natal life, emphasizing the importance of the intra-uterine environment for bone development. Interestingly, postnatal catch-up of bone strength in premature infants occurs only when the stress and the inflammatory state, which accompanies the early postnatal life of preterm infants, is reduced. There is conflicting data regarding the beneficial effect of enriched post discharge formula (PDF) on bone metabolism. Enriched PDF, at least until corrected age of 40 weeks, was found beneficial for bone development, but there is still no convincing evidence to support its beneficial effect after this period. There is mounting evidence to support the notion that assisted exercise (passive, range of motion, and flexion and extension with gentle compression of the large joints) attenuates the natural decrease of bone strength or even increase bone mineralization in premature infants. The mechanism for these beneficial bone effects is not clear; however, it may involve exercise-induced increase in bone formation, leptin, and insulin-like growth factor-I level. Whether the positive bone effects are related to the range of motion exercise per se, or whether the assisted exercise regimen leads to increased overall daily movement in preterm infants in not known. The optimal exercise regimen for this unique population also needs to be determined.

Original languageEnglish
Title of host publicationHandbook of Anthropometry
Subtitle of host publicationPhysical Measures of Human Form in Health and Disease
PublisherSpringer New York
Pages1761-1775
Number of pages15
ISBN (Electronic)9781441917881
ISBN (Print)9781441917874
DOIs
StatePublished - 1 Jan 2012

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