Final answer:
Amyotrophic lateral sclerosis (ALS) causes a decline in voluntary muscle control over time due to the degeneration of motor neurons that control voluntary movements.
Step-by-step explanation:
Amyotrophic lateral sclerosis (ALS) causes a decline in voluntary muscle control over time due to the degeneration of motor neurons that control voluntary movements. As the lateral portion of the spine that controls muscle movement hardens, signals are no longer sent to muscles. Initially, muscles weaken and coordination is affected, and eventually paralysis occurs.