Accel World Wiki

Physical Burst is a feature of the Brain Burst program. As stated by Takumu, Physical Burst is a step below the Physical Full Burst.

A normal Brain Burst accelerates neural activity and thought processes a thousand times by separating the consciousness from the body. Physical Burst accelerates one's conciousness by 10 times for 3 seconds in the real world, making it feel like 30 seconds in acceleration to the burst linker. The burst linker is then able to move their real body in an accelerated state, albeit, 10 times slower than normal to them.

However, using the Physical Burst depletes 5 burst points. As such, it is advised to avoid using it whenever possible due to its highly exhaustive nature.