Thanks to Tom Kindlon for this one!
(May be reposted)
I think these exercise test-retest protocols make sense when one considers
what Dr Melvin Ramsay described:
"Muscle fatigability. Even after a minor degree of physical excercise, 3 or
more days may relapse before full muscle power is restored. This feature is
unique and is the "sheet anchor" of diagnosis. In moderate cases there may
be normal muscle power in remission."
"This applies particularly to the dominant clinical feature of
profound fatigue. While it is true that there is considerable
variation in degree from one day to the next or from one time of the
day to another, nevertheless in those patients whose dynamic or
conscientious temperaments urge them to continue effort despite
profound malaise or in those who, on the false assumption
of 'neurosis', have been exhorted to 'snap out of it' and 'take
plenty of exercise' the condition finally results in a state of
constant exhaustion. This has been amply borne out by a series of
painstaking and meticulous studies carried out by a consultant in
physical medicine, himself an ME sufferer for 25 years. These show clearly
that recovery of muscle power after exertion is unduly prolonged. After
moderate exercise, from which a normal person would
recover with nothing more than a good night's rest, an ME patient
will require at least 2 to 3 days while after more strenuous exercise
the period can be prolonged to 2 or 3 weeks or more. Moreover, if
during this recovery phase, there is a further expenditure of energy
the effect is cumulative and this is responsible for the unrelieved
sense of exhaustion and depression which characterises the chronic
case."
Tom
---------------------------------------
http://www.cfids.org/cfidslink/2008/020602.asp?tr=y&auid=3349064
Science and Legal News on Postexertional Malaise
From 2006 to 2007, the CFIDS Association of America, through your donations,
funded a study by investigators at the University of the Pacific that
investigated the physiologic basis of postexertional malaise in CFS. Two
papers describing interesting results from this study were published
back-to-back in the December issue of the Journal of Chronic Fatigue
Syndrome.
Both papers address testing the functional capacity of CFS patients at more
than one time point interval-what the investigators call a "test-retest"
approach. One paper, "Diminished Cardiopulmonary Capacity During
Postexertional Malaise," identifies a reproducible physical marker when CFS
patients are subjected to an exercise test-retest protocol. The other paper,
"Legal and Scientific Considerations of the Exercise Stress Test," explores
the use of a test-retest protocol for assessing CFS-related disability.
Physical exercise often exacerbates the symptoms that characterize CFS,
resulting in a postexertional relapse that can last for 24 hours or more. In
fact, postexertional malaise is a hallmark of CFS, and many investigators
have used exercise testing to identify markers of fatigue. Most (basic,
non-CFS) exercise physiology studies focus on the ability of the body to
transport and use oxygen. To survive and to carry out activity, the body
must extract oxygen from the atmosphere and transport it to every cell in
the body, where it's used for essential metabolic processes. Oxygen and
energy are inexorably linked.
When an exercise stress test is done in a lab, the subject performs a
physical activity (like riding a stationary bicycle) while wearing a mask
that determines how much oxygen is consumed-otherwise known as VO2, for
volume of oxygen consumed. Blood pressure and heart rate are also monitored
the entire time. An important aspect of the exercise test is to ensure that
the subject is exerting maximal physical effort and not feigning fatigue.
This is done by calculating a respiratory quotient that measures the
chemical and physical changes that occur during metabolism.
Reduced capacity is evident using the test-retest approach
----------------------------------------------------------
In the cardiopulmonary capacity paper by J. Mark VanNess, PhD, Christopher
Snell, PhD, and Staci Stevens, the research team studied six CFS patients
and six healthy but sedentary control subjects by putting them through an
exercise test on two consecutive days. The first exercise test showed no
differences between CFS patients and healthy controls. However, after the
second exercise test 24 hours later, CFS patients displayed significantly
decreased oxygen consumption-both when compared to the mean, or middle, VO2
of their first test and when compared to the VO2 of the healthy controls
during the second test. The authors concluded that "the fall in oxygen
consumption among the CFS patients on the second test suggests metabolic
dysfunction rather than sedentary lifestyle as the cause of diminished
exercise capacity in CFS."
The researchers noted that the CFS patients demonstrated maximal effort on
both exercise tests. They also suggest that decreased oxygen consumption on
day 2 is a distinctive feature of CFS since cardiopulmonary exercise
test-retest protocols in other conditions, such as pulmonary hypertension,
cystic fibrosis and obstructive pulmonary disease, do not show a similar VO2
decrease. This strongly supports the suspected oxidative and metabolic
dysfunction that has been hypothesized as associated with CFS pathology.
Implications for CFS disability claims
--------------------------------------
The paper by Margaret Ciccolella, EdD, JD, and Stevens, Snell and VanNess
examined the legal and scientific considerations of the exercise stress test
for CFS disability claims-demonstrating the shortfalls of using a single
test to determine disability in people with CFS.
The exercise stress test is one of several tools used by the Social Security
Administration (SSA) to determine disability. For CFS disability, as with
all other conditions, the SSA requires two things: proof of the existence of
a medically determinable impairment and the inability to do any kind of
work. The SSA considers an abnormal exercise test an objective medical
impairment for CFS.
In order to receive disability benefits for CFS,the evidence for both the
medically determined impairment and inability to work must be objective. An
exercise test is objective, but as the test-retest study (described above)
demonstrates, a single exercise test does not show a difference in oxygen
consumption between people with CFS and healthy controls. Used alone, a
single exercise test may not return compelling evidence for a CFS disability
claim. However, a second test conducted 24 hours after the first exercise
challenge likely would provide the objective documentation of postexertional
malaise. According to the authors, the initial data from this study suggests
that "the test-retest format offers a superior basis to establish disability
consistent with SSA policy and other relevant case law."
This research, funded through the CFIDS Association's research program, is
just one example of how your financial support is helping to increase our
knowledge of CFS and lead to practical benefits for CFS patients. For more
information about the studies that led to these papers, see "Exercise
Testing Uncovers Abnormalities in CFS."
http://www.cfids.org/cfidslink/2007/030704.asp
VanNess M, Snell C, Stevens S. Diminished cardiopulmonary capacity during
post-exertional malaise. Journal of Chronic Fatigue Syndrome 2007; 14(2):
77-85
Ciccolella M, Stevens S, Snell C, VanNess M. Legal and scientific
considerations of the exercise stress test. Journal of Chronic Fatigue
Syndrome 2007; 14(2): 61-75
(Unfortunately, the Journal of CFS is not indexed through PubMed and other
online medical resources. Contact Haworth Press
http://www.haworthpressinc.com/ to obtain copies of the December 2007
issue.)
____________________
Research matters. Through donations from individuals like you, the CFIDS
Association of America has become the largest source of CFS research money
aside from the federal government.
If accelerating the pace of CFS research matters to you, donate now
http://mycausecfs.kintera.org/cfidsassn .
Extracts from descriptions of ME by Dr Melvin Ramsay:
"Muscle fatigability. Even after a minor degree of physical excercise, 3 or
more days may relapse before full muscle power is restored. This feature is
unique and is the "sheet anchor" of diagnosis. In moderate cases there may
be normal muscle power in remission."
"This applies particularly to the dominant clinical feature of
profound fatigue. While it is true that there is considerable
variation in degree from one day to the next or from one time of the
day to another, nevertheless in those patients whose dynamic or
conscientious temperaments urge them to continue effort despite
profound malaise or in those who, on the false assumption
of 'neurosis', have been exhorted to 'snap out of it' and 'take
plenty of exercise' the condition finally results in a state of
constant exhaustion. This has been amply borne out by a series of
painstaking and meticulous studies carried out by a consultant in
physical medicine, himself an ME sufferer for 25 years. These show clearly
that recovery of muscle power after exertion is unduly prolonged. After
moderate exercise, from which a normal person would
recover with nothing more than a good night's rest, an ME patient
will require at least 2 to 3 days while after more strenuous exercise
the period can be prolonged to 2 or 3 weeks or more. Moreover, if
during this recovery phase, there is a further expenditure of energy
the effect is cumulative and this is responsible for the unrelieved
sense of exhaustion and depression which characterises the chronic
case."
No comments:
Post a Comment