Deputy Police Commissioner Mike Bush says there has been no reduction in the number of front line police staff while officers complete a mandatory fitness test.
About 5% of the force - or 361 officers - have not passed the physical competency test which they are required to do in order to work in front line jobs.
Constables, sergeants and senior sergeants have to take the test every two years. The timed course includes running, leaping, dragging objects and climbing over walls and through windows.
In a new rule introduced on Friday officers must have a current pass before being used in front line roles.
Mr Bush said because staff are often deployed with tasers, pepper spray, handcuffs and sometime firearms, they need to be fit, healthy and able.
He said the officers in question have either failed the test, are injured, or are in rehabilitation.
Mr Bush said the number of front line staff who failed is actually very small, and they have been replaced by others who passed the test until they complete it successfully.