Conclusion
The series of studies summarized in this article provide support for the Energy Envelope Theory as an approach to the rehabilitation management of CFS. This theory would recommend that health care professionals who treat patients with CFS incorporate strategies that help patients self-monitor and self-regulate energy expenditures. Learning to pace activities and stay within the energy envelope appears to have favorable outcomes for patients with CFS. Non-pharmacologic rehabilitative interventions are used for people with cancer and heart disease, but they are only one part of the treatment plan, and, when used by themselves, they are not curative. Similarly, helping patients with CFS remain within their energy envelopes is only one part of a rehabilitation plan.
Much attention of researchers has focused on the potential benefits of cognitive behavioral and graded exercise interventions. For example, in a review paper, Van Cauwenbergh et al. [
46] concluded that randomized studies support exercise treatment using a time-contingent approach, yet this is contradicted by patient surveys. Kindlon[
47] suggests that this discrepancy may be due to the heterogeneity of patients in the different trials and the way in which the harms and treatment compliance have been reported in the randomized trials. As mentioned earlier, the long-term outcomes of this type of intervention are still unclear, but interventions that challenge basic patient illness beliefs may solidify already negative attitudes of medical personnel toward people with CFS. The Energy Envelope Theory and pacing represent alternative approaches for helping patients with CFS. These approaches involve helping patients to better monitor energy levels, stay within their energy envelopes, sustain lifestyle changes that involve reprioritizing activities, and possibly rebalance their lifestyles between work and leisure.
Being overextended and exceeding energy reserves can be an impediment to improving functionality and reducing fatigue levels. Kindling is an explanation of what might occur when patients with CFS overexert themselves and deplete energy reserves.[
48] The kindling hypothesis suggests that once a patient's system is charged, either by high-intensity stimulation or by chronically repeated low-intensity stimulation, activities that involve going beyond energy reserves may enhance an already high level of arousal. In a sense, patients with CFS might have this type of cortical excitability that may be due to kindling. When they go beyond their energy reserves, the kindling results in high arousal, which has implications for the hypothalamus, the autonomic nervous system, and the immune system. Within the brain, areas of the prefrontal cortex and anterior cingulate influence the amygdala, and kindling in these areas could cause continuous sympathetic nervous stimulation that would eventually lead to glandular depletion.[
49] Other CFS research suggests that long-term sensory receptor activation may lead to sensitization of the spinal cord and brain systems that transmit fatigue signals, causing long-term fatigue enhancement within the central nervous system.[
50–54] Interventions that focus on energy balance and pacing might reduce the kindling and sensitization that could be occurring among patients with CFS. This understanding of CFS symptoms suggests potential difficulties using graded activity approaches, which encourage higher levels of activity regardless of symptoms.
The Energy Envelope approach to CFS symptom management and rehabilitation has important implications for health care practitioners who see individuals with CFS. Although this approach is not curative, it may provide this patient population with strategies to aid in symptom management, which can significantly improve the quality of life for these individuals. There certainly is a need to include biological measures within future clinical trials with these types of approaches so that we can learn about who may profit most from these non-pharmacologic rehabilitation approaches, using outcomes beyond self-report measures.[
34,
36]
