Exercises that strengthen the back are helpful in integrating retained primitive reflexes like moro, atnr, stnr, spinal galant, landau, and TLR.
Developing strong extensor muscle is a large and important part for getting an infant ready to sit up and eventually walk. Increased muscle tone and the help and eventually integration of primitive reflexes work together to not only getting us moving in an upright position but also to help the brain develop.
Extensor muscles help with balance and give large amounts of sensory input to our brains. Sensory input from our muscles is a large contributor to brain development and primitive reflex integration. Kids with retained primitive reflexes often have low muscle tone. They will also have a flexor tone that is typically stronger than their extensor tone.
This is only getting worse with our modern way of living and lack of movement.
While flexors are important, most individuals need more help with their extensors.