18.5: Exercise and Post-Stroke Fatigue

18.5.1. Definition and Description

Stroke describes the brain damage caused by either a blockage or rupture of the blood vessels which carry oxygenated blood to the brain. It is estimated that over 30 million people worldwide have survived a stroke, and it is estimated that between 25% and 85% of these people experience post-stroke fatigue (PSF). PSF can reduce the quality of life and negatively impacts activities of daily living for many months and years after stroke, even after successful rehabilitation of motor and cognitive function. The development of strategies and therapies to help reduce and manage fatigue is a priority for people who have had a stroke and has thus become a priority for researchers and clinicians (Ingles et al., 1999).

Though multiple definitions for PSF exist, Lynch and colleagues have described PSF as a period of at least two weeks when an individual who has had a stroke experienced fatigue and a lack of energy, or an increased need to rest nearly every day or every day and this fatigue led to difficulty taking part in everyday activities (Lynch et al., 2007). The causes of PSF are unclear. The majority of people who have had a stroke report feeling fatigued in the weeks afterwards and this is often referred to as"early" PSF. However, not all of these people go on to experience chronic or "late" PSF. Indeed, a small number of people only experience fatigue some months after having a stroke. This suggests that chronic PSF is not a direct consequence of injury to the brain but of the long-term consequences of the stroke on brain structure and function. Whilst the location of the stroke might be related to early PSF, it does not appear to relate to chronic PSF. Several psychosocial and biological mechanisms of chronic PSF have been proposed. A number of studies have shown that chronic PSF is associated with post-stroke depression (Schepers et al., 2006; Spalletta et al., 2005). There is some evidence that chronic PSF may also be related to pre-stroke depression, though one must be cautious when interpreting these studies because there is a risk of recall bias. PSF is also associated with a locus of control directed at more powerful others, such as clinicians, rather than a high internal locus of control. Possible biological mechanisms include increases pro-inflammatory markers, reduced corticomotor drive, and physical impairment (Doncker et al., 2017).

18.5.2. The Role of Exercise in Treating Post-Stroke Fatigue

Exercise has been proposed as a treatment for chronic PSF. In their 2014 Physical Activity and Exercise Recommendations for Stroke Survivors and 2016 Guidelines for Adult Stroke Rehabilitation and Recovery, the American Stroke Association suggests that exercise may help alleviate PSF (Billinger et al., 2014; Winstein et al., 2016). Stroke patients often do not meet the recommended guidelines for daily activity, and up to 75% of people who have a stroke are characterized as sedentary. However, perhaps surprisingly, there is limited evidence that exercise alleviates PSF. In a small pilot study, Clarke et al. (2012)suggested that a lifestyle education intervention, which included physical exercise education, was effective in reducing PSF. Perhaps surprisingly, at the time of writing, the only direct evidence for the effects of exercise on PSF has been provided from a single randomized controlled trial by Zedlitz and colleagues (Zedlitz et al., 2012). These authors reported that the addition of a graded exercise protocol to a cognitive-behavioural intervention doubled the number of people who reported a clinically relevant reduction in PSF compared to when just the cognitive intervention was applied. The exercise program was delivered so that it was tailored to the participants' individual heart rates, and intensity was increased every two weeks. Although this small study provides some evidence of the effect of exercise on PSF, it has yet to be replicated and does not provide any information about the mechanisms by which PSF might be alleviated. Why, then, is exercise a recommended treatment for PSF? One reason might be that exercise has many positive effects on people with stroke, and thus the prescription of exercise is recommended regardless of its effect on fatigue. However, much more research is needed about the effects of exercise after a stroke so that we can understand the types and volume of exercise required to provide meaningful help to patients in whom fatigue is a burden

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