day repeat exercise testing in CFS (i.e. do two exercise tests, 24
hours or so apart):
Snell CR, Stevens SR, Davenport TE, Van Ness JM. Discriminative
Validity of Metabolic and Workload Measurements to Identify
Individuals With Chronic Fatigue Syndrome. Phys Ther. 2013 Jun 27.
[Epub ahead of print]
Extract from Jennifer's blogpost:
"In Test 1, the CFS patients did not perform as ...well as controls.
Multiple measurements were lower in the CFS group, including VO2max,
peak workload, and workload at the anaerobic threshold. However, only
the peak workload difference was statistically significant. In Test 2,
the differences were quite dramatic. The controls performed the same
or even better on the second test. But the CFS patients demonstrated a
drop in VO2max, oxygen consumption at the anaerobic threshold, peak
workload, and workload at the anaerobic threshold. The mean for the
last value – workload at the anaerobic threshold – dropped by more
than 50%. Respiratory measurements prove that all subjects gave a
maximal effort in both tests, so the reduction is not due to lack of
Here's an extract from the full text she has access to:
"This functional deficit may provide an objective indication of PEM.
Despite considerable patient heterogeneity with respect to illness
duration and type of onset, analysis of data from the second test was
able to correctly classify 49 out of 51 individuals with CFS and 9 out
of 10 controls."