She says that CFS is a new form of "effort syndrome", a disorder with a long history.

He directed a study of the condition known as "soldier's heart" and, having established it was not a cardiological problem, renamed it the "effort syndrome".

In 1918 he wrote the monograph The Soldier's Heart and the Effort Syndrome.

It is also variously known as cardiac neurosis, chronic asthenia, effort syndrome, functional cardiovascular disease, neurocirculatory asthenia, primary neurasthenia, subacute asthenia and irritable heart.

There are many names for the syndrome, which has variously been called cardiac neurosis, chronic asthenia, effort syndrome, functional cardiovascular disease, neurocirculatory asthenia, primary neurasthenia, and subacute asthenia.

They included so-called "effort syndrome" that afflicted veterans of the Civil War and World War I, chronic brucellosis, hypoglycemia, myalgic encephalomyelitis, chronic candidiasis and chronic mononucleosis.

During World War One while in the RAMC EB Gunson assisted Thomas Lewis, the noted clinical scientist, in achieving an improved understanding of the Effort Syndrome.

The disorder also closely resembles the so-called effort syndrome, which afflicted veterans of the Civil War and World War I, as well as the Gulf War syndrome that now plagues some veterans of the Persian Gulf War.