The chronometric (time-related) phenomenon described in traditional medicine is quite similar to the biological clock in modern medicine and it is usually used to explain the time-related circulation of qi through the meridian system. Because the qigong acupressure therapy is applied at the acupoints of the meridians, it is of course closely relate to flow of qi through the meridian and the qigong acupressure practioners may choose an adequate time to treat the patient. For example, at noon (11-13 o'clock), i.e. Wu o'clock in Chinese chronometry, qi is flowing through the Heart Meridian, it is the best time to treat patients with heart diseases by qigong acupressure therapy.