Ankle sprains are the most common ankle injury in today's competitive athlete. Pain and swelling can keep an athlete benched at the heighth of the playing season. Restoring the joint to normal as quickly as possible becomes the goal.
It sounds like your daughter may have received a treatment called electrical stimulation (ES). An electrical current or impulse can be passed through the skin via flat electrodes applied to the muscle. The electric current applied is low-voltage with just enough energy to cause the muscle to contract. This type of ES is called neuromuscular electrical stimulation (NMES).
By contracting and relaxing the muscles through multiple cycles, a pump action is created. This muscle pump helps keep fluid from pooling thus decreasing or minimizing edema. Instead, blood and lymph fluid are moved away from the ankle into the leg and back up toward the heart.
Usually a 30-minute treatment session with five second contractions can create 360 cycles. This is far more muscle pumping than a person can do by actively contracting the muscle. As your daughter experienced, the result can be rapid recover and return to sports.