The physical activity program is based on the Moyer-Mileur et al protocol (1). Briefly, this protocol involves extension and flexion range-of-motion exercise against passive resistance of both the upper and lower extremities. Both extension and flexion were performed five times at the wrist, elbow, shoulder, ankle, knee, and hip joints (about 10 minutes for each session). Infant in group 1 have the physical activity intervention once a day, 5 days a week. Infant in group 2 will have the same physical activity intervention twice a day, five times a week. Infant in group 3, the control group will have a similar time (10 minutes) of daily interactive periods of holding and stroking without range-of-motion activity.