London, Jan 14 (IANS): Reducing fears that exercise or activity would make symptoms worse is the key to treating people with chronic fatigue syndrome (CFS), says a study.

CFS is a condition whose defining symptom is exhaustion. It affects everyday life with varying degrees of severity.

Existing treatments for CFS aim to reduce fatigue (exhaustion) and improve physical function by improving a patient's ability to walk, or to do everyday tasks which most people take for granted.

"Our results suggest that fearful beliefs can be changed by directly challenging such beliefs or by simple behaviour change with a graded approach to the avoided activity," said professor Trudie Chalder from Kings College London in Britain.

Fears that exercise or activity will make symptoms worse is an understandable reaction to CFS.

For the study, the researchers used a statistical method called mediation analysis to identify the factors, which are key to treating CFS.

Of all the mediating factors analysed, the researchers found that a reduction in fear avoidance beliefs was the strongest, accounting for up to 60 percent of the overall effect of two existing CFS therapies -- cognitive behaviour therapy (CBT) and graded exercise therapy (GET) -- on outcomes.

The findings could lead to new or improved therapies for CFS.

The study appeared in the journal The Lancet Psychiatry.