Little and often is the pattern for a tiny, stiff rabbit
Little-and-often movement suits an elderly Netherland Dwarf rabbit with stiff joints, because his very small body warms up fast, tires fast, and gains more from five short outings than from one ambitious session. Five to ten minutes of floor time, several times a day, keeps a dwarf's joints moving without the strain that leaves a tiny senior sore afterwards.
Confidence matters at this size. A Netherland Dwarf who feels exposed in a big open room will sit frozen rather than exercise, so shrink the space with a pen or furniture until the area feels like an extension of his home base.
Keep every destination within a few hops
Close spacing turns floor time into real exercise for an elderly Netherland Dwarf. Set his hide, hay pile, water, and a small forage patch within a few hops of each other, so a stiff little rabbit can complete satisfying trips and rest between them instead of facing crossings that feel like expeditions.
Add distance in body-lengths, not metres. Moving the hay one or two dwarf body-lengths further each week is a genuine progression for a Netherland Dwarf, and it keeps the challenge scaled to the animal actually doing it.
Soft, grippy footing protects small joints
Soft, high-grip footing protects an elderly Netherland Dwarf's joints, because a slip that a large rabbit absorbs can wrench a dwarf's small legs badly. Fleece mats or low-pile carpet over any hard floor give his feet purchase, and the padding cushions each landing from the short hops he still enjoys.
Block off slippery shortcuts. If a Netherland Dwarf can cut across bare laminate to reach his hay, he will, so arrange the pen so the grippy path is also the only path.
Handling during exercise stays minimal
Minimal handling keeps exercise positive for an elderly Netherland Dwarf, since being scooped up is stressful for most dwarfs and stiff joints make being held awkwardly a real discomfort. Open the pen door and let him walk out onto the mat himself, and let him walk back when he has had enough.
If he must be moved, slide a hand under his chest and support his hindquarters fully, keeping the lift low and brief. A Netherland Dwarf who associates floor time with being grabbed will start refusing to come out, and the exercise habit dies with the trust.
Reading a dwarf's signals and knowing when to call the vet
Watch an elderly Netherland Dwarf's whole posture to judge a session: ears up and nose working means he is engaged, while sitting pressed into a corner with ears flat means the space or the session has become too much. End on the engaged version, even if only a few minutes have passed.
A vet visit is due if he stops hopping symmetrically, drags a back foot, or loses interest in floor time he used to enjoy. Logging his session pattern and any change in his hop in KinsLe's Pet Passport gives the vet precise detail for such a small patient, where small changes carry big meaning.