18.2: Prioritizing the Patient Experience

In exercise science, there is a tendency to focus on performance fatigability and use the term fatigue when referring to objective decrements in performance. There is also a tendency to place more value on objective measurements (such as a decrease in force during a motor task) rather than subjective self-report measures. Using the term fatigue in this way may originate from a focus on the sport or athletic performance. However, using fatigue to mean performance does not always reflect how the general public understands the term fatigue (a feeling of weariness, tiredness or exhaustion). In the case of clinically relevant chronic fatigue, the emphasis on objective (or even actual) fatigue makes little sense. There are many examples where a measure of fatiguability (such as a decline in muscle force during a sustained submaximal contraction) is deemed to be a more important measure than a patient's self-reported experience of fatigue. However, such objective measures are not inherently superior to a person's experience, and this is particularly important to emphasize in relation to clinical populations with chronic fatigue. A patient does not come to the clinic because they can no longer sustain a submaximal contraction of the forearm muscles. Patients come to the clinic because, for example, they are feeling overwhelming tiredness that is reducing their ability to go about their normal daily activities (e.g., interacting with family and friends, concentrating on completing work tasks, the ability to walk to the shops without causing a huge energy crash) and reducing their quality of life. In fact, most patients would only think something like sustained handgrip force was important if an exercise scientist told them it was. And what would happen if, for example, we improved the ability of the patient to sustain this handgrip force, perhaps by strengthening the forearm muscles used in the task? Would the patient's chronic fatigue then be treated? Of course not. The patient experience, reported to the clinician or scientists, is what matters. Patient-reported outcomes are questionnaires that are used to get a rating of fatigue from the patient and often ask questions about fatigue severity or intensity, and interference with usual activities, and dimensions/manifestations of fatigue (e.g., physical, mental, emotional). Some questionnaires are disease-specific and have been carefully validated (for example, based on clinical features of fatigue in a specific disease, qualitative interviews, and expert clinical consensus). That is, they are highly relevant to the patient. In the sections below, we will be concentrating on the effect of exercise on fatigue measured as a patient-reported outcome in several clinical populations.

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