Which modalities are used to activate muscle contractions?

• A. NMES, FES, and IFT
• B. Ultrasound and phonophoresis
• C. Laser therapy
• D. Cryotherapy

Answer: (A)

Electrical stimulation activates muscle contractions by delivering currents that depolarize motor nerves, making the muscles contract. Neuromuscular electrical stimulation (NMES) is designed specifically to provoke these contractions to strengthen or re-educate muscles. Functional electrical stimulation (FES) uses the same principle to produce purposeful, task-oriented movements, such as lifting a foot during walking. Interferential therapy can also produce a motor response when the device is set to motor-level parameters, allowing the underlying muscles to contract.

In contrast, modalities like ultrasound and phonophoresis rely on sound energy to heat tissues or enhance medication delivery, not to trigger muscle contractions. Laser therapy uses light to influence cellular processes, not to evoke immediate muscle activity, and cryotherapy lowers tissue temperature and can alter nerve conduction without causing muscle contractions.