Chickens need healthy outdoor exercise just as much as any other living creature.
They need the vitamins from the sun just like we do.
They get minerals by pecking around in the soil and grass is a healthy supplement to their usual diet.
Chickens were created to be active and outdoors.
Caging them permanently isn't natural and can make them act peculiar like pecking one another to the point of cannibalism.
The Run - The outside run is contained by standard poultry netting strung from the hen house walls out around two stout posts sunk a good 18 inches into the ground.
Dig the post holes at least a foot across and fill the space around the posts with rocks wedged in tight.
Mix some Portland cement, sand and enough water so that the mixture flows around the rocks.
This mixture will create a solid anchor around the rocks and posts and the wooden posts will last longer if surrounded by concrete.
Most any hard wood will do for the posts, especially if the sub-ground level portion has been soaked in a bucket of creosote for a week or more, though red cedar, cypress and redwood all have natural anti-rot protection built in.
Chicken netting can't be stretched like wire fencing, so it must be framed in and should be five feet in height.
Secure the top of the netting to the posts.
Along the bottom of the run, bury six-inch boards.
Staple the bottom of the netting to the boards.
This anchors the netting and prevents any creature from digging under to get into the pen for a free meal.