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Ambulatory monitoring of physical activity & Symptoms in FM and CFS (2005)

WillowJ

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Kop WJ, Lyden A, Berlin AA, Ambrose K, Olsen C, Gracely RH, Williams DA, Clauw DJ. "Ambulatory monitoring of physical activity and symptoms in fibromyalgia and chronic fatigue syndrome." Arthritis Rheum. 2005 Jan;52(1):296-303. PMID: 15641057

Abstract

OBJECTIVE: Fibromyalgia (FM) and chronic fatigue syndrome (CFS) are associated with substantial physical disability. Determinants of self-reported physical disability are poorly understood.

This investigation uses objective ambulatory activity monitoring to compare patients with FM and/or CFS with controls, and examines associations of ambulatory activity levels with both physical function and symptoms during activities of daily life.

METHODS: Patients with FM and/or CFS (n = 38, mean +/- SD age 41.5 +/- 8.2 years, 74% women) completed a 5-day program of ambulatory monitoring of physical activity and symptoms (pain, fatigue, and distress) and results were compared with those in age-matched controls (n = 27, mean +/- SD age 38.0 +/- 8.6 years, 44% women).

Activity levels were assessed continuously, ambulatory symptoms were determined using electronically time-stamped recordings at 5 time points during each day, and physical function was measured with the 36-item Short Form health survey at the end of the 5-day monitoring period.

RESULTS: Patients had significantly lower peak activity levels than controls (mean +/- SEM 8,654 +/- 527 versus 12,913 +/- 1,462 units; P = 0.003) and spent less time in high-level activities when compared with controls (P = 0.001).

In contrast, patients had similar average activity levels as those of controls (mean +/- SEM 1,525 +/- 63 versus 1,602 +/- 89; P = 0.47).

Among patients, low activity levels were associated with worse self-reported physical function over the preceding month. Activity levels were inversely related to concurrent ambulatory pain (P = 0.031) and fatigue (P < 0.001).

Pain and fatigue were associated with reduced subsequent ambulatory activity levels, whereas activity levels were not predictive of subsequent symptoms.

CONCLUSION: Patients with FM and/or CFS engaged in less high-intensity physical activities than that recorded for sedentary control subjects. This reduced peak activity was correlated with measures of poor physical function.

The observed associations may be relevant to the design of behavioral activation programs, because activity levels appear to be contingent on, rather than predictive of, symptoms.
 

WillowJ

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The interesting thing about the above results is that the patients do not have high peak activity as compared to sedentary controls, yet their average activity is similar. This does not support the idea that such patients are engaging in a boom-bust or push-crash cycle.

Most research examining determinants of physical function in FM/CFS is based on methods that may have inherent biases, because both symptoms and physical function have been recorded using retrospective, self-reported data.

When asked to retrospectively report symptoms, individuals do not accurately integrate all their experiences over a given period of time; instead, there is a tendency to report peak symptoms and most recent symptoms (21).

Moreover, individuals modify retrospective symptom reports on the basis of their symptoms and moods at the time of survey completion (22). To minimize this retrospective bias, the present study uses continuous, automated activity monitoring and repeated symptom assessments throughout the day.

Good points!

In summary, this study shows that when FM/CFS patients are compared with control subjects with similar overall activity levels, they have reduced peak levels of activity and no consistent exacerbation of symptoms after periods of increased activity.

This suggests a vicious cycle whereby symptoms may lead to inactivity, and inactivity (via both neurobiologic and psychological mechanisms) leads to increased symptoms.

Patients attribute exacerbations of symptoms to a wide range of factors, including exercise, and therefore, fear or avoidance of increased activity and exercise may occur and further reinforce this cycle (38).

Future mechanistic and interventional studies will be necessary to confirm these findings, and to determine if more effective interventions can be designed to simultaneously target physical activity and symptom management.

It's difficult to say for sure because they change the terminology, but they do not appear to have assessed the temporal relationship between activity and symptoms past 30 minutes. This is not enough to capture PEM/PER/PENE.

Their data does not support an unhealthy fear of activity. I think this is an unreasonable conclusion since they did find an association between reduced activity and concurrent symptoms, and increased activity and reduction in symptoms (thus, patients are indeed increasing activity as able).

These data do not support a "vicious cycle" as claimed; for that there would have to not be an increase when feeling better, relative to activity when feeling worse, or at least relative to the previous good spell. They do not demonstrate any such pattern.

Furthermore they seem to have ignored a great deal of published literature establishing a worsening of condition in CFS with exercise or exertion of any kind.
 

ahimsa

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Any study which measured "activity" as movement only, and did not consider orthostatic stress (standing, sitting upright), would not accurately assess a patient that had any type of Orthostatic Intolerance (NMH or POTS).

For example, is standing still or sitting still counted as an activity or counted as being sedentary? I could walk for 5 minutes much more easily than I could stand still for 5 minutes. Based on the following extract from the full text of this study I believe that the walking would be counted as activity and the standing still would not:

Ambulatory physical activity levels were assessed using an actigraph accelerometer ... The actigraph is a wristwatch-sized (37 x 29 x 9 mm), light-weight (17 gm) device that has been validated previously (28,29). Actigraphs contain a piezo-electric sensor that generates a voltage when the device undergoes a change in acceleration. The actigraph is most sensitive to movement perpendicular to the device. Actigraphs were placed on the wrist and, consequently, are most sensitive to the natural movements of the arm but adequately assess whole-body movements (28,30).

This sounds to me like sitting still or standing still would count as "no activity."
 

Snow Leopard

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Their data does not support an unhealthy fear of activity. I think this is an unreasonable conclusion since they did find an association between reduced activity and concurrent symptoms, and increased activity and reduction in symptoms (thus, patients are indeed increasing activity as able).

These data do not support a "vicious cycle" as claimed; for that there would have to not be an increase when feeling better, relative to activity when feeling worse, or at least relative to the previous good spell. They do not demonstrate any such pattern.

Quite frankly, I found the conclusions bizarre. The fact that patients have a more consistent activity level=boom/bust? Sounds like a non sequitur.

Likewise, patients would have had to INCREASE their activity levels beyond their limits if we wished to test the hypothesis whether increasing activity levels leads to increased symptoms.

Luckily there have been studies that have investigated just that:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC555551/
http://www.ncbi.nlm.nih.gov/pubmed/21254053
 

WillowJ

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bizarre, yes.

there isn't even any internal consistency in these models. on the one hand, patients are supposed to have an unreasonable fear of activity, but on the other, they are supposedly approaching activity in an "all or nothing manner" or throwing themselves fully into activity during a "boom"... doesn't sound too fearful to me!

of course, neither supposition is true: this paper itself (and a more recent study by Julia Newton's group, which was recently pointed out to me) disproved the boom part, and the studies SL posted disproved the irrationality of the patients' expectation of increased symptoms from activity.
 

Dolphin

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bizarre, yes.

there isn't even any internal consistency in these models. on the one hand, patients are supposed to have an unreasonable fear of activity, but on the other, they are supposedly approaching activity in an "all or nothing manner" or throwing themselves fully into activity during a "boom"... doesn't sound too fearful to me!
Yes, when one starts thinking about these models they start breaking down.

of course, neither supposition is true: this paper itself (and a more recent study by Julia Newton's group, which was recently pointed out to me) disproved the boom part
Well, technically more the "bust" part - that people boom and then bust and end up spending too much time at a low level which causes problems:
This (Kop et al) study, found no difference in low- and very low-intensity activities (see Table 2)

and similarly
Newton JL, Pairman J, Hallsworth K, Moore S, Pltz T, Trenell MI. Physical activity intensity but not sedentary activity is reduced in chronic fatigue syndrome and is associated with autonomic regulation. QJM. 2011 Aug;104(8):681-7. Epub 2011 Mar 7.
found there was no increase in the amount of time people with CFS were sedentary compared to others.
 

WillowJ

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ok, yes. :Retro smile: I forgot about that already.

do you see any significance in the low peaks of activity in the patient groups?
 

Dolphin

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do you see any significance in the low peaks of activity in the patient groups?
Short answer: they may be trying to avoid "booming and busting"!

And possibly: some patients' bodies often won't let them do high peaks of activity, even if they do try (for some people, perhaps all the time; for others, they might be able to have higher peaks some of them time, but are more ill at other times and can't).

------
The significance of the studies I think works better on the "bust" part: they might say, because of a lack fitness/deconditioning, people would still be "booming" at a lower intensity (i.e. it wouldn't have to be high intensity to qualify as "booming").

The stereotype often put out is that people take to their beds. Also they talk about the problems of bed rest in "healthy people"/people who don't have ME/CFS, and how it can cause the symptoms (they select to highlight) of ME/CFS. However, the studies show people don't engage in increased low/very low intensity activity.
 

WillowJ

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The significance of the studies I think works better on the "bust" part: they might say people would still be "booming" at a lower intensity (i.e. it wouldn't have to be high intensity to qualify as "booming") because of a lack fitness.

this was what I was asking; thanks.

even though the sedentary controls also lack fitness, is the presumption that the patients (the ones who turn out for exercise studies) have less fitness? how about the 2001 Bazelmans study which found patients not less fit? or are we just avoiding overstating our side of the case?
 

Dolphin

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even though the sedentary controls also lack fitness, is the presumption that the patients (the ones who turn out for exercise studies) have less fitness? how about the 2001 Bazelmans study which found patients not less fit? or are we just avoiding overstating our side of the case?
Not exactly sure what you mean in the last sentence. The Bazelmans et al (2001) study, funnily enough, tends not to be mentioned. I'm not sure many of the CBT/fear avoidance school of thought have tried to explain the finding away very much.
 

WillowJ

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I'm not sure many of the CBT/fear avoidance school of thought have tried to explain the finding away very much.

yes, they just ignore whatever they don't like; that way they needn't evaluate their models! then they take to the media and say it's the patients who don't understand the scientific method. it would be funny, if it weren't so deadly serious.
 

Dolphin

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The SF-36 Physical functioning subscale is often used in ME/CFS trials (incl. the PACE Trial). Thus, I thought the following was interesting:
Ambulatory activities and symptoms of patients
in relation to self-reported function. Ambulatory peak
activity levels had a positive correlation with better
self-reported physical function as determined by higher
SF-36 scores (physical role r=0.45, physical function
r=0.30; both P<0.05), but there was no significant
association between peak activity levels and selfreported
pain (r=0.21, P=0.22) or general health (r 
0.22, P=0.35). Associations between average activity
levels and self-reported physical function were in the
same direction, but were statistically nonsignificant (P> 
0.1).
(from Discussion)
Peak activity, but not average
activity, also has an association with self-reported measures
of physical function, suggesting that patients are
reporting their inability to engage in high-level activities
when completing such questionnaires.
 

WillowJ

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that's very interesting; thanks for posting it here.

Here's a demo of the SF-36 in case anyone wants to see the questions
http://www.sf-36.org/demos/SF-36.html

While looking for something completely different, I also found a letter questioning the validity of the "boom and bust" (or push/crash) model - since the model is contradicted by a Belgian study which found, "Compared to healthy controls, no indication was found that the CFS patients as a group were characterised by a high number of large day-to-day fluctuations in activity."

I know you're familiar with the letter, Dolphin, but I thought it was worth citing in this thread.