Can exercise limits prevent post-exertional malaise in chronic fatigue syndrome? An uncontrolled clinical trial.

<b>Objective</b>: It was hypothesized that the use of exercise limits prevents symptom increases and worsening of their health status following a walking exercise in people with Chronic Fatigue Syndrome (CFS). <b>Design</b>: An uncontrolled clinical trial (semi-experimental design). <b>Setting</b>: Outpatient clinic of a university department. <b>Subjects</b>: 24 patients with CFS. <b>Interventions</b>: Subjects undertook a walking test with the two concurrent exercise limits. Each subject walked at an <i>intensity</i> where the maximum heart rate was determined by heart rate corresponding to the respiratory exchange ratio =1.0 derived from a previous sub-maximal exercise test and for a duration calculated from how long each patient felt they were able to walk. <b>Main outcome measures</b>: The Short Form 36 Health Survey or SF-36, the CFS Symptom List, and the CFS-Activities and Participation Questionnaire were filled in prior to, immediately and 24 hours post-exercise. <b>Results</b>: The fatigue increase observed immediately post-exercise (p=0.006) returned to pre-exercise levels 24 hours post-exercise. The increase in pain observed immediately post-exercise was retained at 24 hours post-exercise (p=0.03). Fourteen of 24 subjects experienced a clinically meaningful change in bodily pain (change of SF-36 bodily pain score ³10). Six of 24 participants indicated that the exercise bout had slightly worsened their health status, and 2 of 24 had a clinically meaningful decrease in vitality (change of SF-36 vitality score ³20). There was no change in activity limitations/participation restrictions. <b>Conclusion</b>: It was shown that the use of exercise limits (limiting both the intensity and duration of exercise) prevents important health status changes following a walking exercise in people with CFS, but was unable to prevent short-term symptom increases

Potassium Channel and NKCC Cotransporter Involvement in Ocular Refractive Control Mechanisms

Myopia affects well over 30% of adult humans globally. However, the underlying physiological mechanism is little understood. This study tested the hypothesis that ocular growth and refractive compensation to optical defocus can be controlled by manipulation of potassium and chloride ion-driven transretinal fluid movements to the choroid. Chicks were raised with +/−10D or zero power optical defocus rendering the focal plane of the eye in front of, behind, or at the level of the retinal photoreceptors respectively. Intravitreal injections of barium chloride, a non-specific inhibitor of potassium channels in the retina and RPE or bumetanide, a selective inhibitor of the sodium-potassium-chloride cotransporter were made, targeting fluid control mechanisms. Comparison of refractive compensation to 5mM Ba2+ and 10−5 M bumetanide compared with control saline injected eyes shows significant change for both positive and negative lens defocus for Ba2+ but significant change only for negative lens defocus with bumetanide ; ; ; ; ; ). Vitreous chamber depths showed a main effect for drug conditions with less depth change in response to defocus shown for Ba2+ relative to Saline, while bumetanide injected eyes showed a trend to increased depth without a significant interaction with applied defocus. The results indicate that both K channels and the NKCC cotransporter play a role in refractive compensation with NKCC blockade showing far more specificity for negative, compared with positive, lens defocus. Probable sites of action relevant to refractive control include the apical retinal pigment epithelium membrane and the photoreceptor/ON bipolar synapse. The similarities between the biometric effects of NKCC inhibition and biometric reports of the blockade of the retinal ON response, suggest a possible common mechanism. The selective inhibition of refractive compensation to negative lens in chick by loop diuretics such as bumetanide suggests that these drugs may be effective in the therapeutic management of human myopia

Activity pacing: moving beyond taking breaks and slowing down

This brief communication responds to the paper by Jeong and Cho (Qual Life Res 26(4):903–911, 2017) that has described activity pacing in limited terms of adjusting activities through going at a slower rate and taking breaks. Activity pacing was reported as not involving goal setting, in comparison to other strategies for long-term conditions such as Acceptance and Commitment Therapy. This brief communication aims to challenge this limited perception of activity pacing in light of numerous studies that recognise pacing to be a more complex strategy. Pacing is considered to be a multifaceted coping strategy, including broad themes of not only adjusting activities, but also planning activities, having consistent activity levels, acceptance of current abilities and gradually increasing activities, and one that includes goal setting as a key facet. It is essential that pacing is both defined and measured as a multifaceted strategy in order to assess the outcomes of pacing, and for meaningful comparisons with other strategies regarding efficacy for the management of long-term conditions

A case control study of premorbid and currently reported physical activity levels in chronic fatigue syndrome

BACKGROUND: Patients with chronic fatigue syndrome typically report high levels of physical activity before becoming ill. Few studies have examined premorbid and current activity levels in chronically fatigued patients. METHODS: In a case-control study, 33 patients with chronic, unexplained, disabling fatigue attending a university-based clinic specializing in fatigue were compared to 33 healthy, age- and sex-matched controls. Patients rated their activity levels before their illness and currently, using scales designed for this purpose. Controls reported their level of activity of 2 years previously and currently. Chi-square analyses, Student's t tests, and Wilcoxon signed rank tests were used in pair matched analyses. RESULTS: Compared to healthy controls, patients with chronic, unexplained fatigue rated themselves as more active before their illness (p ≤ 0.001) and less active currently (p ≤ 0.001). The patients also reported they currently stood or walked less than the controls (median [inter-quartile range] = 4 [2-5] versus 9 [7.5–12] hours, p ≤ 0.001), and spent more time reclining (median [inter-quartile range] = 12 [10-16] versus 8 [8–9.5] hours, p ≤ 0.001). These differences remained significant for the subset of patients who met strict criteria for chronic fatigue syndrome or fibromyalgia. CONCLUSION: Patients with chronic, unexplained, disabling fatigue reported being more active before becoming ill than healthy controls. This finding could be explained by greater premorbid activity levels that could predispose to illness, or by an overestimation of previous activity. Either possibility could influence patients' perceptions of their current activity levels and their judgments of recovery. Perceived activity should be addressed as part of management of the illness

Protocol for the "four steps to control your fatigue (4-STEPS)" randomised controlled trial: a self-regulation based physical activity intervention for patients with unexplained chronic fatigue

<p>Abstract</p> <p>Background</p> <p>Unexplained Chronic Fatigue is a medical condition characterized by the presence of persistent, severe and debilitating medically unexplained fatigue, leading to impaired functioning and lower quality of life. Research suggests that physical activity can contribute to the reduction of fatigue and other somatic symptoms and can thus significantly improve physical functioning and quality of life in these patients. Based on the self-regulation (SR) theory of behaviour change, we developed a brief physical activity program for patients suffering from unexplained chronic fatigue which focuses on the training of self-regulation skills, the "4-STEPS to control your fatigue" program.</p> <p>Methods/Design</p> <p>This is a multi-centre, randomised controlled trial (RCT) that will be carried out in local primary care centres and at the Portuguese Fibromyalgia and Chronic Fatigue Syndrome Patients Association. Patients aged between 18 and 65 and fulfilling operationalized criteria for Idiopathic Chronic Fatigue (ICF) and Chronic Fatigue Syndrome (CFS) will be recruited and randomly allocated to standard care (SC) or standard care plus a self-regulation based physical activity program (4-STEPS). Patients will be assessed at baseline, after the intervention (3 months) and at 12 months follow-up. The primary outcome is fatigue severity.</p> <p>Discussion</p> <p>The results of the RCT will provide information about the effectiveness of a brief self-regulation intervention for promoting physical activity in patients with unexplained chronic fatigue. If the program proves to be effective, it may be considered as an adjunctive treatment for these patients.</p> <p>Trial Registration</p> <p>ISRCTN: <a href="http://www.anzctr.org.au/ISRCTN70763996.aspx">ISRCTN70763996</a></p