Heat and stretch procedures: an evaluation using rat tail tendon.

This study evaluated various methods of applying force to collagenous tissue at various temperatures to produce permanent elongation, using rat tail tendon as the tissue model. A materials testing machine was used to measure the forces applied and the resulting elongation produced by differing procedures. Short-term vigorous stretching and prolonged moderate stretching were compared at 37 C. The effect of heating tissue prior to applying force was evaluated, and the effect of using a prolonged application of low force was demonstrated. The data showed that the low force, long duration procedure was very effective at producing residual elongation. Elevating tissue temperature and maintaining it prior to applying force was found to cause significantly less damage; and finally, the lower loads applied at elevated temperatures for prolonged periods were found to produce significantly greater residual elongation.