What if overbreathing wasn’t the result of hypertension and headaches but the cause? Buteyko wondered. Heart disease, ulcers, and chronic inflammation were all linked to disturbances in circulation, blood pH, and metabolism. How we breathe affects all those functions. Breathing just 20 percent, or even 10 percent more than the body’s needs could overwork our systems. Eventually, they’d weaken and falter. Was breathing too much making people sick, and keeping them that way?