Answer
People who are bound to wheelchairs have thin and weak legs and high bones because the bones are no longer subjected to weight-bearing stress and therefore lose calcium. Atrophy occurs to the muscles when you cannot use them anymore and loss of density causes them to generally weaken.more. Loss of density causes them to generally weaken.
Work Step by Step
Just think that if you did bicep curls every day for 2 months your biceps would go through hypertrophy which means that you bicep muscles will get bigger. Now lets just not use our biceps for 2 months. Our biceps would go through atrophy and our biceps would become smaller.