What is the pulse frequency used in IFC for muscle contraction?

The correct pulse frequency for muscle contraction using Interferential Current (IFC) typically falls within the range of 50-120 pps. This frequency range is effective for eliciting muscle contractions because it provides an adequate stimulation to recruit muscle fibers. At these frequencies, the action potentials generated in the muscle tissue lead to strong and synchronous contractions, which can be beneficial for muscle strengthening and rehabilitation.

The lower frequency range (20-25 pps, as indicated in the answer choice) is typically associated with pain modulation rather than muscle contraction. Therefore, while different frequencies can serve particular therapeutic purposes, for muscle contraction specifically, the 50-120 pps range is deemed optimal.