Final answer:
Brief-intense TENS is a pain modality used for procedural pain. It does not flip between frequencies, and it is not the most common TENS used for acute injuries. It is used to evoke pain and release endogenous opioids.
Step-by-step explanation:
Brief-intense TENS, or transcutaneous electrical nerve stimulation, is a pain modality used for procedural pain. It is used to create some pain before or during a procedure so that the patient doesn't experience a more intense and uncomfortable pain. However, the statement that it flips back and forth between frequencies so that the patient cannot adapt to the TENS being applied is not correct. TENS typically uses a constant frequency.
Brief-intense TENS is not the most common TENS used for acute injuries like an ankle sprain. In fact, it is often used for chronic pain conditions.
Brief-intense TENS is used to evoke pain and muscular pain in order to release endogenous opioids, which are naturally occurring pain-relieving chemicals in the body.
It is important to note that the effectiveness of Brief-intense TENS may vary depending on individual factors and the specific condition being treated.