What is causing low water pressure at master shower faucet or shower head what can be done to correct

Is this a change, something new or has it always been that way, Have you changed shower heads or the valve?

It is not really the pressure that is the problem, it's the volume is limited. You likely have a restriction due to debris collecting in the shower head, cartridges and/or aerators. Is the rest of the house just fine? Tell us all you can about the valves that have restrictions.

Hello, if its only on your shower and it's the same pressure on both hot and cold then more than likely its going to be the shower head, they come with flo restrictors which you can see if you take off the shower head and look into the threaded part. Most have a screen to prevent debre from clogging up the ports, and limit the amount of water that can pass through the shower head. Good luck ----Zeke--

Zeke is on to something with the flow restrictors (water savers).
Unscrew the shower head and look inside to find a rubber washer with holes around the edge. This will be the flow restrictor, pry it out and toss it. Pressure better now? Good luck, tom