We aimed to assess whether a twice daily assisted exercise interventional program will have a greater effect on bone strength compared to a once daily intervention or no intervention in very low birth weight (VLBW) preterm infants. Thirty-four very VLBW preterm infants (mean BW 1217 ± 55 g and mean gestational age 28.6 ± 1.1 weeks) were randomly assigned into one of three study groups: twice daily interventions (n = 13), a once daily intervention (n = 11), and no intervention (control, n = 10). The intervention was initiated at a mean of 8 ± 2.4 days of life and continued for 4 weeks. It included passive extension and flexion range-of-motion exercise of the upper and lower extremities. Bone strength was measured at enrollment and after 2 and 4 weeks using quantitative ultrasound of tibial bone speed of sound (SOS, Sunlight Omnisense™). At enrollment, the mean bone SOS was comparable between the twice daily interventions, once daily intervention and control groups (2918 ± 78, 2943 ± 119, and 2910 ± 48 m/s, respectively). As expected, the bone SOS declined in all groups during the study period (−23.6 ± 24, −68.8 ± 28, and −115.8 ± 30 m/s, respectively, p < 0.05), with a significantly attenuated decrease in bone strength in the twice daily intervention group (p = 0.03). A twice daily intervention program of assisted range-of-motion exercise attenuates the decrease in bone strength and may decrease the risk of osteopenia and future fractures in VLBW preterm infants.
Osteopenia Physical activity Quantitative ultrasound Speed of sound
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Internal departmental sources.
Dr. Ita Litmanovitz conceptualized and designed the study, drafted the initial manuscript and approved the manuscript as submitted. Hedva Erez enrolled the infants into the study and performed the assisted exercise. Prof. Alon Eliakim was involved in the study design, interpretation of the results, and reviewed and revised the final draft of the manuscript. Dr. Sofia Bauer-Rusek was responsible for bone QUS measurements and approved the final version of the manuscript. Dr. Shmuel Arnon designed the data collection and revised the final draft of the manuscript. Dr. Rivka Regev was involved in data collection, and reviewed and revised the manuscript. Dr. Gisela Sirota carried out the nutritional management and anthropometric measurements, and reviewed and revised the manuscript. Prof. Dan Nemet designed the study, carried out the statistical analysis, and reviewed and revised the final draft of the manuscript.
Compliance with Ethical Standards
Conflict of Interest
Ita Litmanovitz, Hedva Erez, Alon Eliakim, Sofia Bauer-Rusek, Shmuel Arnon, Rivka H. Regev, Gisela Sirota, and Dan Nemet have no conflict of interest relevant to this article to disclose.
Human and Animal Rights and Informed Consent
This study was approved by the institutional human research committee of Meir Medical Center, Kfar Saba, Israel. Preterm infants born at the Medical Center were eligible for study participation if they met the following criteria: BW < 1500 g, BW appropriate for GA, postnatal age of less than 2 weeks, and the provision of informed parental consent.
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