Becker, P., Roeykens, J., Reynders, M., McGregor, N., De Meirleir K. Exercise
capacity in chronic fatigue syndrome. Archives
of Internal Medicine, 2000, 160, 3270-3277.
with CFS suffer from various symptoms, including debilitating fatigue, muscle
pain, and muscle weakness. Many experience marked functional impairment. In this
study, the researchers evaluated the exercise capacity in a large cohort of
female patients with CFS.
compared 427 women with CFS (CDC criteria '88 or '94) and 204 matched sedentary
control subjects who all performed a maximal test with graded increase on a
bicycle ergometer. Gas exchange ratio was continuously measured. In a second
stage, they examined only those persons who achieved a maximal effort as defined
by 2 end points: a respiratory quotient of at least 1.0 and an age-predicted
target heart rate of at least 85%.
resting heart rate of the patient group was higher, but the maximal heart rate
at exhaustion was lower, relative to the control subjects. The maximal workload
and maximal oxygen uptake attained by the patients with CFS were almost half
those achieved by the control subjects. Analyzing only those persons who
performed a maximal exercise test, similar findings were observed.
compared with healthy sedentary women, female patients with CFS show a
significantly decreased exercise capacity. This could affect their physical
abilities to a moderate or severe extent. Reaching the age-predicted target
heart rate seemed to be a limiting factor of the patients with CFS in achieving
maximal effort, which could be due to autonomic disturbances."
decrease in physical capacity in patients with CFS appears to be associated with
disease severity and is consistent with the reduction seen in many other chronic
is a very interesting article although it might have been more illuminating if
the researchers had compared and contrasted subgroups (e.g. post infection
versus gradual onset), and if they had repeated the test 24 hours later (to
assess post-exertional exercise capacity).