Deep tissue massage is intended for athletes or someone who suffers with an injury. Deep tissue targets deep layers of tissue like muscles, tendons, and fascia (fascia is like seran wrap that wraps around individual muscles, groups of muscles, and organs) that a Swedish massage would not get to.
This massage tends to cause some pain. If you find yourself holding your breath, please notify your therapist to decrease the pressure. It is normal to experience some pain for the next couple of days after your treatment.