In bracing or functional electrical stimulation (FES) settings, which describes the on:off duty cycle?

• A. 1:5
• B. Depends
• C. 1:1
• D. 1:2

Answer: (B)

In FES and bracing setups, the on:off duty cycle describes how long the stimulator is active (on) versus how long it rests (off) in each cycle. This ratio controls how much the muscle contracts versus how much it recovers, which directly affects fatigue, comfort, and how well the contraction lines up with the movement you’re trying to achieve. There isn’t a single fixed ratio that fits every person or task. The best duty cycle is tailored to the individual’s muscle response, tolerance, and the activity or phase of movement you’re aiming to assist. For someone who tires quickly, you’d use a longer off time (for example, a more conservative on:off ratio) to prevent rapid fatigue and maintain function. For someone who tolerates stimulation well and needs more sustained effort, the ratio might be shorter. In short, the duty cycle is decision-based and adjusted to fit the specific situation, which is why “Depends” is the right way to think about it.