The effects of exercise on body weight and circulating leptin in premature infants

Objective: To assess the effect of daily movements on weight gain, serum leptin, and insulin-like growth factor I (IGF-I) in premature infants. Study Design: Twenty very-low-birth-weight premature infants were matched and randomized to a daily movement (n = 10) and control groups (n = 10). Daily movement consised of passive range of motion with gentle compression of both the upper and lower extremities 5 days per week for 4 weeks. Results: Daily movements led to a significant increase in weight gain (784 ± 51 vs 608 ± 26 g in movements and controls, respectively, p<0.02), and to a significant increase in leptin (0.60 ± 0.19 vs 0.13 ± 0.06 ng/ml in movements and controls, respectively, p<0.05). Changes in body weight correlated with changes in serum lepin (r=0.48, p<0.03). IGF - I also increased following daily movements (18.8 ± 4.1 vs 9.2 ± 4.1 ng/ml in movements and controls, respectively); however, this increase was not statistically significant. Conclusion: A relatively brief range of motion daily movement intervention was associated with greater weight gain and increased leptin levels in very-low-birth-weight premature infants. This may suggest that at least part of the daily movements associated with increase in body weight resulted from an increase in adipose tissue.