Early physical activity intervention prevents decrease of bone strength in very low birth weight infants.
OBJECTIVE
To evaluate the effect of early range-of-motion intervention on bone strength and bone turnover in very low birth weight infants.


METHODS
Twenty-four infants (mean birth weight: 1135 +/- 247 g; mean gestational age: 28.5 +/- 2.3 weeks) were matched for gestational age and birth weight and then randomly assigned into exercise (n = 12) and control (n = 12) groups. Exercise protocol started at the first week of life and involved daily extension and flexion range of motion against passive resistance of the upper and lower extremities (5 minutes per day, 5 days per week, 4 weeks). Growth parameters, bone strength, and biochemical markers of bone homeostasis were measured at enrollment and after 4 weeks. Bone strength was determined using quantitative ultrasound measurement of bone speed of sound (SOS) at the middle left tibial shaft.


RESULTS
Bone SOS decreased significantly in the control group during the study period (from 2892 +/- 30 m/sec to 2799 +/- 26), whereas bone SOS of the exercise group remained stable (2825 +/- 32 m/sec and 2827 +/- 26 m/sec at baseline and 4 weeks, respectively). This significant difference in bone SOS was not expressed in the biochemical markers of bone homeostasis.


CONCLUSIONS
There is a significant postnatal decrease in the bone SOS of very low birth weight infants. A brief range-of-motion exercise attenuates the decrease in bone strength and may decrease the risk of osteopenia.
Litmanovitz
Ita
I
Department of Neonatology, Meir General Hospital, Sapir Medical Center, Kfar Saba, Israel. litmani@clalit.org.il
Dolfin
Tzipora
T
Friedland
Orit
O
Arnon
Shmuel
S
Regev
Rivka
R
Shainkin-Kestenbaum
Ruth
R
Lis
Monika
M
Eliakim
Alon
A
D015502:Absorptiometry, Photon; D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers; D015519:Bone Density; D001846:Bone Development; D001851:Bone Diseases, Metabolic / Q000517:prevention & control*; D016723:Bone Remodeling; D001862:Bone Resorption; D005081:Exercise Therapy; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D008297:Male; D016059:Range of Motion, Articular; D013977:Tibia / Q000000981:diagnostic imaging; D016896:Treatment Outcome; D014463:Ultrasonography
D015415:Biomarkers; D000469:Alkaline Phosphatase