When 'Fire' Builds Up, Does the Body Stiffen? The Hidden Cause of Chronic Muscle Pain

From the perspective of modern medicine, 'fire' described in Donguibogam can be explained as chronic stress and the resulting imbalances in the nervous and hormonal systems. When we experience stress, our body's emergency response system, the sympathetic nervous system, is activated. This is just like switching into fight-or-flight response mode. Heart rate speeds up, blood pressure rises, and muscles instantly enter a state of tension. While this state helps to temporarily escape a crisis, problems arise when this tension fails to release and persists for a long time. Chronic stress continuously stimulates the hypothalamic-pituitary-adrenal axis (HPA axis) and increases the secretion of the stress hormone cortisol. While cortisol also plays a role in regulating inflammatory responses, excessive long-term secretion can actually promote a systemic inflammatory response and lower immunity. As muscles remain in a continuous state of tension, the supply of oxygen and nutrients becomes compromised, and as waste products accumulate, trigger points develop. In particular, muscles in areas vulnerable to stress, such as the neck, shoulders, back, and lower back, begin to knot firmly like stones. This chronic muscle tension impedes blood circulation and compresses nerves, creating a vicious cycle that further aggravates pain. Pain essentially begets pain. Additionally, stress affects the brain's pain perception system. Chronic stress increases sensitivity to pain, causing one to feel stronger pain even from minor stimuli. As the balance of neurotransmitters such as serotonin and norepinephrine is disrupted, pain modulation function declines, leading to feelings of depression or anxiety that can form a loop triggering muscle tension once again. It is as if the body and mind are joining hands and hurting together. Ultimately, the 'fire' in Donguibogam is very similar to the chronic stress response explained in modern medicine. Persistent tension of body and mind causes autonomic nervous system imbalance, adversely affects the function of muscle cells and microvessels, and induces a state of systemic inflammation, resulting in chronic muscle pain and fatigue. We can see that the wisdom of ancient forebears—that one must manage hot 'fire' in the body—aligns remarkably well with modern medicine's advice to restore bodily balance through stress management. It is truly important not to ignore your body's signals and to warmly nurture it.