In active range-of-motion (AROM) stimulation, what is the typical on:off ratio?

• A. 1:5
• B. 1:3
• C. 1:1
• D. 1:2

Answer: (C)

The main idea is choosing a duty cycle that supports smooth, continuous movement during active range-of-motion stimulation while keeping fatigue in check. A 1:1 on:off ratio means the stimulator is on for an equal amount of time as it is off. This creates a steady rhythm of contraction and relaxation that helps the limb move through the desired arc without one long, sustained contraction that tires the muscle too quickly. It provides enough assist to complete the range while giving the muscle regular recovery periods.

Ratios with more off time would interrupt the movement pattern and make it harder to progress through the full arc, while shorter or more continuous on-time would fatigue the muscle more quickly and risk an abrupt loss of movement quality. Therefore, 1:1 is the typical, balanced approach for AROM stimulation.