Time course of exercise induced alterations in daily activity in CFS, 2005, Black and McCully

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1280928/

Abstract
In a previous study we demonstrated that while people with CFS had lower daily activity levels than control subjects, they were able to increase daily activity via a daily walking program. We reanalyzed our data to determine the time course of activity changes during the walking program. Daily activity assessed via an accelometer worn at the hip was divided into sleep, active, and walking periods. Over the first 4–10 days of walking the subjects with CFS were able to reach the prescribed activity goals each day. After this time, walking and total activity counts decreased. Sedentary controls subjects were able to maintain their daily walking and total activity goals throughout the 4 weeks.

Unlike our previous interpretation of the data, we feel this new analysis suggests that CFS patients may develop exercise intolerance as demonstrated by reduced total activity after 4–10 days. The inability to sustain target activity levels, associated with pronounced worsening of symptomology, suggests the subjects with CFS had reached their activity limit.

 

This brief note was mentioned by @strategist. It's interesting in terms of exercise physiology evidence, but the sample size is very small. I think it's most interesting in terms of history. In 2005, Black and McCully realised that their initial analysis had led them to a faulty conclusion, and they were attempting to inform others.

 

Patients using accelerometers for 4 weeks strongly refutes the claim by PACE that they are an undue burden for patients.