The aim of this study was to evaluate the changes in bone mineral density and anthropometric indices of extremely low birth weight (ELBW) preterm infants undergoing daily physical activity. Twenty-eight low-risk ELBW preterm infants (intervention group = 14, control group = 14) with a birth weight of under 1000 g and gestational age of 26-32 weeks were recruited. Preterm infants in the control group were provided with standard nursing care, whereas those in the intervention group received a daily physical activity programme in addition to standard nursing care during the study. Before and after the study, anthropometric indices and tibial speed of sound (SOS) values were measured. In this study, the tibial SOS values were found to be increased in the intervention group (+111.14 m/s) (p = 0.001) and decreased in the control group (-58.21 m/s) (p = 0.030). The increase in percentage of body weight, height, and tibial length of infants in the intervention group was significantly higher than in the control group (respectively; p = 0.002, p = 0,015, p < 0.001). A daily physical activity programme increased body weight, height, tibial length, and SOS values of the tibia in ELBW preterm infants.