Fig. 4
Changes in the three measures in 20 individuals re-tested after experiencing a clinical deterioration. Individual changes in the %peak VO2 of normal, the physical functioning scale of the SF-36 questionnaire, and the number of steps/day in 20 patients undergoing re-evaluation because of worsening of symptoms. All mean measurements during the re-evaluation showed a significant deterioration (P < 0.0001) in comparison to the initial evaluation. Phys F: Physical Functioning scale of the SF-36 questionnaire; %peak VO2: peak VO2 oxygen uptake relative to controls [37]; No of steps: number of steps per day