3.2.1. Graduated Exercise Therapy
A systematic review of graduated exercise therapy (GET) for chronic fatigue syndrome (CFS) concluded that patients with CFS generally feel less fatigued and their sleep and physical function improve after completing graduated exercise therapy [
38]. Since the update of the NICE guidelines in 2020, GET is no longer recommended. The NICE guidelines do not recommend GET because this treatment is considered to be ineffective and harmful based on evidence from patient surveys and qualitative studies [
39]. This decision has been widely criticized by the scientific community due to the choice of analyzed studies [
40,
41]. In addition, the omission of a recently published meta-analysis of the safety results from ten published studies on GET was strongly objected to [
42]. This study showed that GET is safe as long as it is prescribed properly [
42].
However, it is essential that physical activity be adjusted to the individual’s limit to avoid triggering severe post-exertional malaise. It is therefore imperative to determine the limit of each patient before starting physiotherapy treatment. In the presence of post-exertional malaise, activity management or pacing [
43,
44], as well as heart rate monitoring [
45], may be effective rehabilitation approaches to support the self-management of symptoms.
3.2.2. Pacing
Pacing is a prudent use of resources on a physical, mental, and emotional level. The goal of pacing is to find the optimal and individual balance between rest periods and activation periods (physical, cognitive, and emotional) [
43,
44].
The sustained stabilization of symptoms, which often fluctuate, could guide how activities and rest are modified in response to the individual and frequently subjective symptoms. Quality of rest, sleep, and eating habits can also be considered as part of activity management and may help in the stabilization of symptoms.
Pacing should include setting realistic goals, monitoring physical, cognitive and social activities and their impact on energy levels, and avoiding possible overexertion that could exacerbate symptoms. Pacing is not an activity avoidance strategy, but a strategy to minimize the worsening of symptoms after exertion [
44,
46]. Pacing is often used as part of a set of energy conservation strategies called the “Principle of Three P’s”, namely, prioritization, planning, and pause management [
47].
3.3. Heart Rate Monitoring
Heart rate monitoring is a rehabilitation strategy that can be used by people to self-manage symptoms when living with post-COVID-19 syndrome. Heart rate monitoring is a useful method for people with fatigue to avoid PEM. It refers to the continuous measurement of heart rate with a heart rate monitor, and it is used to more accurately pace daily activities and monitor the body’s responses to exertion. The aim of heart rate monitoring is to stay below the ventilatory anaerobic threshold (VAT) throughout the day, thus avoiding post-exertional malaise [
45]. The exact determination of VAT is carried out with the help of a cardiopulmonary exercise test (spiroergometry). However, this test can lead to post-exertional malaise in some patients. The pulse–threshold rate can also be calculated as an alternative. The Workwell Foundation recommends two methods for calculation [
47]:
-
(220 − age) × 0.55 = guideline (in beats per minute (bpm));
-
Resting heart rate as a measure for activity management. Resting heart rate can be determined by having the person lie flat in bed and calculating the average resting heart rate over 7 days. The benchmark is now set as 15 bpm above the resting heart rate.
Before using heart rate monitoring, autonomic dysfunction (e.g., postural tachycardia syndrome) in the context of post-COVID-19 syndrome must be ruled out, as this makes the use of these methods impractical.
