Fibrosis is a disease that causes abnormal accumulation of collagen and other extracellular matrix components. It can lead to organ failure and is responsible for one-third of all deaths worldwide. However, there is no cure for this disease, and the development of minimally invasive therapies is urgently needed. We have previously reported techniques for adjusting the shape and flexibility of fibrous tissue by traction while denaturing it with heat. However, studies comparing heat and traction on fibrous tissue are limited, so this paper examined that. Applying heat and traction to bovine Achilles tendon tissue has been shown to cause the denaturation of collagen molecules to accumulate in the tissue in response to these loads. Heat-induced collagen denaturation was nondirectional and omnidirectional, whereas mechanical stress-induced collagen denaturation was concentrated in the direction of traction. When both heat and traction were applied, collagen denaturation increased more than under a single load, indicating a synergistic effect.