We focus between the third eye and root because this route awakens the prana to move through the nervous system. Focusing from root to crown is avoided here because that can cause problems with a premature kundalini awakening. They aren't nice.
Why in pranayama are you having two focuses? One on third eye and one from basement of body to third eye?
Hi ettskede:
There are not two focuses of attention. Attention follows the spinal nerve during spinal breathing pranayama between root and brow, as woosa said.
We may also raise the eyes and slightly furrow the brow during spinal breathing practice if we are using sambhavi mudra (an optional later addition). In that case the physical mudra is used while the attention continues to trace the spinal nerve during spinal breathing. It takes some getting used to.
Slight tension should not be a problem. But if it becomes more than slight then the practice routine should be adjusted.
If any practice is causing excessive discomfort, scale back the time of that practice until the symptoms subside. This is called "self-pacing," and it is discussed extensively throughout the AYP lessons for many situations. It is a very important aspect of self-directed practice.
There will be no risk of injury if practices are self-paced according to our capacity. Each will find their own equilibrium in this, reaching a balance between practices and normal daily activity for good long term spiritual progress with comfort and safety.