There are many theories as to the causes of male infertility. In Oriental Medical Theory infertility is associated with a dysfunction of the kidney, liver and spleen organ systems. The kidneys have primary importance because they govern birth, growth, reproduction, and development. They are also credited with being the root of all Yin/Yang energies.
Decreased mobility of sperm is a sign of deficiency of kidney Yang, although this is not the only contributor to decreased sperm mobility. Impotence or loss of libido is another cause of infertility. This affects men stressed by overwork, or the emotional effects of a mid-life crisis. It is seen in younger men overwrought with sexual anxiety or frustration.
Decreased sperm count or abnormal sperm are other causes or infertility. The motility of sperm is primarily a responsibility of kidney Yang while the number of sperm is primarily controlled by kidney Yin.
In clinical practice, Yin and Yang share a mutual interdependence on one another, and so it is not unusual to see a combined deficiency of kidney Yin and Yang that manifests as a low sperm count.