With age muscular can become weaker . this is due to

Sarcopenia is the condition in which muscles become weak because of aging. 
This is normal in all human bodies because it has the tendency of slowly deteriorating through time. 
This condition cannot be prevented. 
Muscles, joints, and bones start to weaken and lose its functions as we age.

Just try to give them some space. don’t cut them off completely or else they could become jealous, just give them some space and time to think. hope this .