Modalities are passive interventions that work on many different levels and require little to no effort or movement on your part. These include treatments such as moist heat, cryotherapy, ultrasound and electrical stimulation as well as many others.
E-stim is the use of a machine to push electrical currents through the injured tissue. Our body is mostly water, making us good conductors of electricity for better or worse. This modality uses a safe and painless level of electrical current in order to facilitate decreased pain, improved circulation, decreased tissue tension, and many more applications. Small electrodes are placed at points near the injured tissue determined by the desired sensory or muscular response desired. Electricity passes from one electrode through the tissue and into the other electrode. Most typically describe the sensation as similar to getting a massage. In some cases E-stim can be used to help a muscle contract more forcefully by altering the electrode placement and increasing the intensity. This is because our muscles contract due to an electrical signal initiated in our brain.
Ultrasound is the use of high frequency sound waves as a form of energy that can reach deeper tissues in our body. The frequency of the sound waves effects how deep the waves have the optimal effect. Ultrasound can be set to continuous modes that generate heat, allowing for a similar effect to moist heat packs but in deeper tissue. There is also a pulsed ultrasound option that is sometimes used to help stimulate tissue healing but with little to no heat generated.
The application of heat or ice is used to alter the blood flow, nerve conduction speeds and sensory input to the injured area. The body reacts to heat by dilating the blood vessels, allowing an increase in blood which brings oxygen and nutrients to the tissue to help with healing. Ice is used to do the reverse. Drops in body temperature cause the body to constrict the blood vessels, reducing the blood flow to the injured area. While it is necessary for healing that blood bring in nutrients, ice is usually applied in the presence of swelling to blunt the inflammatory process in the acute stage of injury to decrease pain. Swelling and pain can be detrimental to the ability of a muscle or joint to move, making ice the priority until the swelling is controlled.