[Only mentions CFS] Physical activity buffers fatigue only under low chronic stress (2016) Nater

Esther12 · Nov 7, 2017

Nater has been one of the most ridiculous CFS quacks imo. He's claimed doubled blind trials show CBT is effective (the site is currently down, but I think this link should take you to that claim when it's back on-line: https://listserv.nodak.edu/cgi-bin/wa.exe?A2=ind1205d&L=co-cure&F&S&P=12748) and has done some really poor work which tried to claim CFS patients' personality disorders could explain why they don't get on well with those promoting CBT/GET. This new paper has one paragraph which could indicate a change from him (the final paragraph quoted).

I only skimmed through this paper, and didn't think it was very interesting, but thought I'd post my notes up in case anyone else was interested.

Paywalled: http://www.tandfonline.com/doi/full/10.1080/10253890.2016.1192121?scroll=top&needAccess=true

Science hub: https://sci-hub.cc/http://www.tandf...53890.2016.1192121?scroll=top&needAccess=true

ABSTRACT Fatigue is one of the most commonly reported complaints in the general population. As physical activity (PA) has been shown to have beneficial effects, we hypothesized that everyday life PA improves fatigue. Thirty-three healthy students (21 women, 22.8±3.3 years, 21.7±2.3kg/m2) completed two ambulatory assessment periods. During five days at the beginning of the semester (control condition) and five days during final examination preparation (examination condition), participants repeatedly reported on general fatigue (awakening, 10 am, 2pm, 6pm and 9pm) by means of an electronic diary, collected saliva samples for the assessment of cortisol and a-amylase immediately after providing information on fatigue and wore a triaxial accelerometer to continuously record PA. Self-perceived chronic stress was assessed as a moderator. Using hierarchical linear modeling, including PA, condition (control vs. examination), sex and chronic stress as predictors, PA level during the 15min prior to data entry did not predict momentary fatigue level. Furthermore, there was no effect of condition. However, a significant cross-level interaction of perceived chronic stress with PA was observed. In fact, the (negative) relationship between PA and fatigue was stronger in those participants with less chronic stress. Neither cortisol nor a-amylase was significantly related to physical activity or fatigue. Our study showed an immediate short-term buffering effect of everyday life PA on general fatigue, but only when experiencing lower chronic stress. There seems to be no short-term benefit of PA in the face of higher chronic stress. These findings highlight the importance of considering chronic stress when evaluating the effectiveness of PA interventions in different target populations, in particular among chronically stressed and fatigued subjects.
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Accordingly, we define fatigue as a subjective state that goes beyond feeling tired and sleepy, cannot be predicted by effort exerted, and interferes with carrying out duties and responsibilities. Stress, especially in the case of chronic stress, seems to play a major role in the development and persistence of this debilitating symptom in various populations (Kurokawa et al., 2011; Pawlikowska et al., 1994).
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Seems odd to define fatigue as something which cannot be predicted by effort exerted. What do they call the 'fatigue' that can be predicted by effort exerted? It doesn't seem surprising that their odd new definition of 'fatigue' would be related to 'stress'.

Since there are substantial discrepancies between subjective reports of PA and objective assessment strategies (Adamo et al., 2009; Prince et al., 2008), we measured activity objectively by means of accelerometry in order to avoid memory bias.
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Good to have it acknowledged.

Their hypothesis:

Current PA was assumed to have an immediate positive effect on general fatigue. We hypothesized that this effect is moderated by perceived chronic stress, with those participants reporting higher chronic stress benefitting more from short-term PA than those with lower chronic stress. Furthermore, salivary cortisol and a-amylase (sAA) have been assessed as markers of the hypothalamic–pituitary–adrenal (HPA) axis and the autonomic nervous system (ANS), respectively. Both markers have been linked to fatigue (Powell et al., 2013; Yamaguchi et al., 2006) and physical activity (Filaire et al., 2013) and will therefore be considered as likely mediators of an immediate short-term PA effect on momentary general fatigue (Silverman & Deuster, 2014).
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33 participants.

Data collection took place during two weeks of the summer semester 2012, the first period at the beginning of the semester (control condition) and the second period covering
students’ preparation for their final examinations (examination condition). During both ambulatory assessment periods, students were examined on five consecutive days. This design enabled us to study effects of PA on fatigue during two conditions of differing stressfulness (Doerr et al., 2015).
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They used apps "to report subjective general fatigue levels five times throughout the day (awakening, 10 am, 2pm, 6pm and 9pm). A sixth data entry 30min after awakening comprised only control items (not reported). Momentary general fatigue was assessed using the item ‘‘At the moment, ... I feel fatigued’’ on a five-point Likert scale from not at all to very (Stone et al., 1997)."

Chronic stress was examined by means of the 12-item Screening Scale of the Trier Inventory for the Assessment of Chronic Stress (SSCS; Schulz et al., 2004), which assesses chronic stress experiences in the past three months on a 5-point Likert scale ranging from never to very often. This scale was completed during the control condition to capture students’ general chronic stress.
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Their results looked like an uninterpretable mess. Here's their discussion.

Discussion
In contrast to our expectation, current everyday-life PA did not significantly influence momentary general fatigue levels in a sample of healthy university students. Testing the hypothesized moderating role of chronic stress yielded mixed findings. While fatigue levels were shown to be higher during the
stressful examination period, condition-related changes in physical activity levels did not account for changes in fatigue scores. On the other hand, perceived chronic stress during the three months prior to study participation moderated the PA–fatigue relationship. PA was more strongly related to attenuated fatigue scores in those participants who experienced less chronic stress. This finding is in contrast to a previous
study showing that PA was associated with subjective wellbeing only on days of high stress and demand (Giacobbi et al., 2007). Our results would challenge a ‘‘stress-buffering hypothesis of physical activity’’ insofar as current PA in everyday life had no buffering effect on momentary general fatigue in the face of chronic stress (Gerber & Puhse, 2009). It might be assumed that under chronic stress, there is no short-term benefit of an increase in PA. Chronic stress might diminish fatigue-buffering effects of daily physical activity and even reverse it,that is everyday activity episodes can be understood as an indicator of a busy, stressful day. Hence, the question arises whether the kind of PA has a meaning in this context. Participants reported more spare time- and less work-related activities in the control condition compared to the examination condition, but there was no difference between low and high chronic stress groups in respect to what they were doing at the time of prompting (data not shown). Furthermore, engagement in regular physical activity needs to be considered. As previously shown, only subjects with regular physical activity as compared to those with irregular or no activity increased their activity under stress (Lutz et al., 2010). In our study, chronic stress scores and total activity counts did not differ with respect to habitual PA, making it unlikely that this factor is a major confounder of our findings. Given our small sample size and unequal group distribution, further research is warranted to examine habitual PA as a moderator of the activity–fatigue association.
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Here's the slightly surprising paragraph on CFS:

The missing short-term benefit of PA corresponds well with observations in patients suffering from the most extreme form of persistent fatigue, that is, chronic fatigue syndrome, who often report a worsening of symptoms after physical and mental exertion (Jammes et al., 2005). This so-called postexertional malaise is an important part of current diagnostic strategies in this disorder and can also be quantified via objective tests (Twisk, 2015). Although increasing PA levels is a major goal in rehabilitation, it is difficult to implement activity programs in these patients. Our findings suggest that the lack of short-term benefit from PA could provide an explanation for why particularly patients under chronic stress hesitate to engage in PA. In line with this, engaging in PA has been considered an additional stressor demanding time and energy (Lutz et al., 2007).
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Luther Blissett · Nov 7, 2017

Thanks Esther.

Although increasing PA levels is a major goal in rehabilitation, it is difficult to implement activity programs in these patients.
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Maybe you could try the revolutionary technique of waiting until after treatment before moving onto rehabilitation?

Trish · Nov 7, 2017

Looks like a classic case of taking a small sample of people and collecting lots of data about them during two time periods and throwing all the mass of data into a computer stats package and hoping something 'significant' might emerge.

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