Assisted exercise improves bone strength in very low birthweight infants by bone quantitative ultrasound

Aim: To evaluate whether assisted exercise could prevent the development of osteopenia of prematurity, we performed assisted exercise in the study group of very low birthweight (VLBW) premature infants. Methods: Sixteen premature infants with birthweight below 1500g were enrolled in this study and randomly assigned into the exercise (n=8) and control (n=8) groups. Assisted exercise involved full extension and flexion range of motion of the upper and lower extremities by a trained nurse with a schedule of 5days a week for a total of 4weeks. Bone strength was determined by quantitative ultrasound measurement of tibial bone speed of sound every 2weeks during the study period. Results: No difference in gender, birthweight, and gestation age between the exercise and control groups was noted. There was statistically significant less tibial bone speed of sound decrease in the exercise group on the sixth and eighth week of life. During the study period, there were no statistically significant differences in blood biochemistry data, including calcium, phosphorus, magnesium, alkaline phosphatase, osteocalcin and osteoprotegerin, between the two groups. Conclusions: This study revealed that early assisted exercise could improve bone strength in very low birthweight infants. The biochemical markers of bone metabolism, osteocalcin and osteoprotegerin, could not be the indicators for early diagnosis of osteopenia of prematurity.