One theory which can be used to explain GET, as outlined in the GET booklet is based on deconditioning which is the gradual decline in physical fitness and strength in the body as a consequence of a reduction in physical functioning. Another theory points to an altered perception of effort (this may be more significant than deconditioning). Researchers have noticed that some people with CFS/ME may experience changes in how they interpret the messages that the body gives them during physical activity.
These changes in both conditioning and perception of effort are thought to be reversible. Therefore, by gradually increasing physical activity, this may enable the body to gain fitness and strength as well as making changes to the perception of effort.
Preliminary research suggests that reduced symptoms (including fatigue) are related to simply participating in a GET programme, rather than necessarily getting fitter, whereas improved functioning is related to getting fitter and stronger. Participants are encouraged to see symptoms as temporary and reversible, as a result of their current relative physical inactivity, and not as signs of progressive pathology.
A mild and transient increase in symptoms is explained as a normal response to an increase in physical activity. Apart from the behavioural and perceptual effects of graded exposure to
GES Therapists Manual GETSET Trial P a g e | 7
previously avoided physical activities, there may be other mechanisms involved in the success of GET such as reversing deconditioning, including elements of habituation, and positive effects of re- engagement with important activities. GET has also been shown to improve sleep, cognition, and mood; factors that are also likely to perpetuate the condition, although these are not directly addressed in the GET booklet or GES itself.
