Tissues heated to 45°C and then stretched exhibit a non-elastic residual elongation of about 0.5-0.9% that persists after the stretch is removed which does not occur in these same tissues when stretched at normal tissue temperatures. Thus 20 stretching sessions can produce a 10-18% increase in length in tissues so heated and stretched. This effect would be especially valuable in working with ligaments, joint capsules, tendons, fasciae, and synovium that have become scarred, thickened or contracted. Such stretching at 45°C caused much less weakening in stretched tissues for a given elongation that a similar elongation produced at normal tissue temperatures.
The experiments cited clearly showed that low-force stretching can produce significant residual elongation when heat is applied together with stretching or range-of-motion exercises, which is also sager than stretching tissues at normal tissue temperatures. This safer stretching effect is crucial in properly training competitive athletes so as to minimize their "down" time from injuries.
There was a 20% decrease in stiffness at 45°C as compared with 33°C in rheumatoid finger joints, which correlated perfectly to both subjective and objective observation of stiffness. Any stiffened joint and thickened connective tissues should respond in a similar fashion.
