heart rate variability (HRV) has been considered as valuable non-invasive test that has been used to investigate the function of the autonomic nervous system. In severe conditions HRV tend to reduce. This is based on the fact that the spatial and temporal variations in heart rate, reflect changes of sympathetic and vagal activity, following postural changes and or physical activity in neonates. Importantly, evidence suggests that the neurocardiac mechanism in high risk infants with neurological damage are less efficient, and less adaptive to exercise, postural change, and physical activity, compared to infants with less or no damage.

Considering this association, HRV has been suggested as a possible marker of brain damage, neurodevelopmental dysfunction, and improvement following exercises, activities, and therapeutic physiotherapeutic interventions. Thus, parameters related to HRV have been used as physiological markers reflective of motoric control, function, and neuromotor developmental level, and milestones