Which type of current is associated with tetanic contraction?

• A. Low Frequency Current
• B. High Frequency Current
• C. Both
• D. Neither

Answer: (A)

Tetanic contraction happens when the muscle receives repeated stimuli so quickly that individual twitches merge into a single, sustained contraction. In electrotherapy practice, this is produced with low‑frequency pulsed currents (roughly in the tens of hertz). At these rates, motor units are activated rapidly enough that relaxation between stimuli is minimized, leading to a fused, strong contraction useful for strengthening. Higher-frequency currents (in the kilohertz range) don’t produce the same controlled tetanus in the same way and are typically used for other therapeutic effects or sensations rather than deliberate, sustained muscle contraction.