Glass ceiling effect

The Glass Ceiling Effect is the effect whereby people with ME/CFS often make a degree of improvement over the period course of time, but then reach a point at which they are unable to increase their physical activity, despite high levels of motivation. The glass ceiling is the limit of available energy that a person with ME/CFS has.

In a study by Black and McCully, chronic fatigue syndrome (CFS) patients were asked to increase their daily physical activity by 30% by walking a prescribed amount each day for a period of four weeks. Daily activity was assessed by an accelerometer worn at the hip. For the first 10 days, CFS patients were able to increase their activity but then experienced a relapse and symptom exacerbation that prevented them from following the activity program any further. According to the authors, "the inability to sustain target activity levels, associated with pronounced worsening of symptomology, suggests the subjects with CFS had reached their activity limit."

Other studies have shown that ME/CFS patients are not able to increase their fitness or amount of daily activity the way healthy persons or other patient groups can, after following an exercise therapy.