This ancient healing method releases all the tension in the muscle and has the ability to instantly relax the recipient. Why do warm stones zap stress from our body? 

A muscle needs to contract or at least have the nerve signal "fire" (as occurs in contraction) before it can relax.

Sometimes the signals are enough to get everything ready to fire, but the signal is not strong enough to actually cause the contraction or discharge the energy from the muscle. An example of this is shoulder pain that comes on after a hard day or from hours of computer work. 

The result is that the muscle tenses, but cannot quite contract and the tension remains and builds up in that muscle, which makes a knot or spasmodic muscle.

When you place a weighted stone on the skin, and gently press the muscle against the underlying bone, it makes it flatten out like a ball of clay would. The sustained application of hot stones on a client, during a treatment, helps the muscle contract repeatedly.