Exercise Tolerance Testing in Adolescents with CFS and Recovered Controls after Mono

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Tate Mitchell to CO-CURE May 8

'Exercise Tolerance Testing in a Prospective Cohort of Adolescents
with Chronic Fatigue Syndrome and Recovered Controls Following
Infectious Mononucleosis'

Katz BZ, Boas S, Shiraishi Y, Mears CJ, Taylor R.
J Pediatr. 2010 May 5. [Epub ahead of print]

Department of Pediatrics, Northwestern University, Feinberg School of
Medicine and Children's Memorial Hospital, Chicago, IL.

http://www.ncbi.nlm.nih.gov/pubmed/20447647


Abstract

OBJECTIVE: Six months after acute infectious mononucleosis (IM), 13%
of adolescents meet criteria for chronic fatigue syndrome (CFS). We
measured exercise tolerance in adolescents with CFS and control
subjects 6 months after IM.

STUDY DESIGN: Twenty-one adolescents with CFS 6 months after IM and 21
recovered control subjects performed a maximal incremental exercise
tolerance test with breath-by-breath gas analysis. Values expressed
are mean +/- standard deviation.

RESULTS: The adolescents diagnosed with CFS and control subjects did
not differ in age, weight, body mass index, or peak work capacity.
Lower oxygen consumption peak percent of predicted was seen in
adolescents with CFS compared with control subjects (CFS 99.3 +/- 16.6
vs control subject 110.7 +/- 19.9, P = .05). Peak oxygen pulse also
was lower in adolescents with CFS compared with recovered control
subjects (CFS 12.4 +/- 2.9 vs control subjects 14.9 +/- 4.3, P = .03).

CONCLUSIONS: Adolescents with CFS 6 months after IM have a lower
degree of fitness and efficiency of exercise than recovered
adolescents. Whether these abnormal exercise findings are a cause or
effect of CFS is unknown. IM can lead to both fatigue and measurable
changes in exercise testing in a subset of adolescents.

Copyright 2010 Mosby, Inc. All rights reserved.
 

Hope123

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It was a good idea to study to compare recovered and non-recovered mono patients but we know from prior studies that it's not so much a one time exercise tolerance test that distinguishes CFS vs. non-CFS groups but rather a repeat exercise test. That is, metabolic measure are similar in both groups after one test but after a second test, the CFS groups' measures decline even more rather than staying stable or improving like healthy controls or even controls with non-CFS chronic diseases (heart/ lung disease, e.g.)
 

Dolphin

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CONCLUSIONS: Adolescents with CFS 6 months after IM have a lower
degree of fitness and efficiency of exercise than recovered
adolescents. Whether these abnormal exercise findings are a cause or
effect of CFS is unknown.
IM can lead to both fatigue and measurable
changes in exercise testing in a subset of adolescents.
I'd be betting on "effect".
 
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but we know from prior studies that it's not so much a one time exercise tolerance test that distinguishes CFS vs. non-CFS groups but rather a repeat exercise test.
I wholeheartedly agree. This was a test of capability, not fatigability (as in chronic FATIGUE syndrome). You'd think that researchers would have worked this out by now. And also, you would surely expect the ill subjects to do worse than the recovered ones, so I'm not quite sure what the purpose of this study was.
 

Dolphin

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I just read the following paper. One thing not covered in the abstract is the following:
--------------
Although they didn't reach significance, these data might be of interest to somebody. I have a vague recollection of reading some CFS patients' cortisol levels dropped after exercising and the results here suggest it happened for some of the CFS patients.

Salivary cortisol response to exercise

The Kruskal Wallis test was used to examine the pattern of
cortisol change in response to exercise in adolescents with
CFS and recovered control subjects. Relative change from
baseline (T1) to immediately after maximal oxygen consumption
(VO2 max) (T2), and immediately after (T2) to
60 minutes after exercise (T3) were compared between cases
and control subjects. Although there seemed to be a greater
rise in salivary cortisol levels in response to exercise in recovered
control subjects (51% increases) compared with cases
with CFS (7% increase), this was not statistically significant.
A sluggish cortisol response in subjects with CFS also is consistent
with subjects with CFS exercising less efficiently than
recovered control subjects (Table III).

Table III. Relationship between exercise and cortisol
response.
1st number:CFS
2nd number:Control
3rd number:p value

Cortisol Values
Mean +/- SD
T1, 10 minutes before 0.8 +/- 0.5 ng/mL 0.9 +/- 0.9 ng/mL .67
T2, Immediately after 0.8 +/- 0.5 ng/mL 1.0 +/- 0.9 ng/mL .39
T3, 60 minutes after 1.2 +/- 1.6 ng/mL 1.3 +/- 1.0 ng/mL .78

Percent change
T1 vs T2 8.7 +/- 56.1 50.5 +/- 137.3 .21
T2 vs T3 155.1 +/- 575.3 126.0 +/- 279.7 .84
 
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Full text inc tables available here

Just wanted to pull out the deconditioning/fitness levels as VO2 max from the paper:


VO2max, ml/min/kg
CFS patients: 37.4
Recovered: 40.9

The differences were not statistically significant. Population norms for group of this age that is 85% female is around 40-49 so recovered patients (after 6 months) are scraping average while CFS patients are a bit below average, but by no means abnormal.
 

Dolphin

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Full text inc tables available here

Just wanted to pull out the deconditioning/fitness levels as VO2 max from the paper:


VO2max, ml/min/kg
CFS patients: 37.4
Recovered: 40.9

The differences were not statistically significant. Population norms for group of this age that is 85% female is around 40-49 so recovered patients (after 6 months) are scraping average while CFS patients are a bit below average, but by no means abnormal.
Thanks.

Probably not important but there's a slight discrepency with the PubMed Central file: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2975670/pdf/nihms-191571.pdf . Recovered are down as 41.7 but still not statistically different from non-recovered.