Energy Envelope Theory

Energy Envelope Theory is a self-management tool developed and tested by Dr. Leonard Jason to reduce symptom severity and the frequency of relapses for people with ME/CFS. According to this theory, ME/CFS patients should not expend more energy than they perceive they have, as this results in post-exertional malaise and higher disability. Instead patients are advised to stay within their energy envelope, meaning the physical limits the disease has imposed upon them. As the energy envelope theory also cautions about the dangers of under-exertion, its principles are almost identical to ‘pacing’, an activity management strategy for ME patients devised by Ellen Goudsmit in the UK.

Several studies have demonstrated that ME/CFS patients who balance their energy expenditure and ‘stay within their envelope’, have fewer symptoms and recover to a higher level of functioning than those who don't. The Energy envelope theory has been promoted by patient organizations  and the CDC as an effective component in the treatment of ME/CFS.

History
In the early 1990s the research team of health psychologist Leonard Jason at the DePaul University of Chicago decided to investigate the activity level of ME/CFS patients into more detail. By using hourly and daily monitoring of symptoms, they were able to examine the relationship between exertion and setbacks. Following up on several case studies, the Jason research group found that an elevation of symptoms was often preceded by an increase in activity.

In a 1999 study, Jason et al. used an innovative approach to assess overexertion. They asked the ME/CFS patient participating in the study to rate his perceived and expended energy separately on a 100 point scale, with 0 meaning to have no energy at all and 100 to feel completely well. If the ratio of those two scores, exceeded 100, this meant the patient was overexerting himself. Results showed that this energy quotient was significantly correlated with fatigue several days later. According to the authors: “The finding that fatigue was significantly and positively related to self-rated physical exertion two days ago suggests that excesses in activity eventually increase fatigue in this person with Chronic Fatigue Syndrome.”

At the same the Jason group was developing a social program where ME/CFS patients were granted a buddy and mentor to help them with daily hassles. While buddies were often university students who volunteered to do some chores for patients, mentors were veteran ME/CFS patients helping others by passing on their experience in coping with the illness. Many of the advices ME/CFS patients gave each other were about how to avoid overexertion and relapses by balancing energy expenditure. It was a member of this buddy/mentor program who proposed calling this strategy the “Energy Envelope Theory.”

Accept the limits the illness imposes
The energy envelope theory is based on acceptance of ME/CFS as a severe chronic condition that deeply impacts the lives of persons that suffer from it. The theory advises working within the limits imposed by the illness rather than fighting against it. Jason et al. have acknowledged the similarities of this approach with acceptance and commitment therapy (ACT).

Stay within the envelope
The key advice of the envelope theory is to stay within the envelope, meaning the limits ME/CFS imposes. Under the Energy Envelope Theory, treatment programs that recommend a steady increase in daily activity, such as Graded exercise therapy (GET), are discouraged because the person with ME/CFS may exceed the amount of energy available for that day, thereby initiating post-exertional malaise or an increase in symptoms. By balancing energy expenditure and availability, patients can diminish the number of setbacks and act at a higher level of functioning. Paradoxically, by doing less, ME/CFS patients might be able to do more.

Avoid underexertion
At the same time the envelope theory also warns about the dangers of too little activity. According to Jason et al. “it is important to avoid under-exertion, which might involve increasing activity for some individuals.” This constituted the main criticism of Activity Pacing Therapy (APT), the form of pacing used in the PACE trial. APT promoted the use of pre-emptive rest and the 70%-rule. Patients were advised to not exceed 70% of their perceived amount of energy. According to Jason, this advice might have unwanted consequences: "“By doing less than what patients have the energy to do, and the resulting pre-emptive rest, this intervention could even have the unwitting effects of increasing social isolation.”"The energy envelope theory advises patients to do as much as they can without triggering post-exertional malaise and relapses. The phrase ‘staying within the envelope’ does not simply mean ‘don’t do too much’. Instead it refers to “a comfortable range of energy expenditure, in which an individual avoids both over-exertion and under-exertion, maintaining an optimal level of activity over time.”

Not a cure
The envelope theory suggests that, if perceived and expended energy levels are kept at the same level, ME/CFS patients will slowly gain strength and energy. By staying in the envelope, patients will experience fewer crashes and symptoms of severe fatigue. This might enlarge the envelope and expand the limits ME/CFS imposes on patients. The envelope theory is however no cure or treatment of ME/CFS, but a strategy that helps patients cope with the illness.

Scientific evidence
Several in-depth case studies support the Energy Envelope theory. In a 2000 study, 3 patients were given a buddy to teach them how to stay within the envelope and how to cope with the illness. This helped reduce fatigue severity over time. A similar study assessing the combination of a mentor/buddy program and the envelope theory involved 30 ME/CFS patients who were randomly assigned to the intervention or a control condition. The intervention was effective in reducing fatigue and increasing vitality, but there were no effects on physical functioning and stress.

In 2004 the envelope theory was part of a broad multidisciplinary program that also included cognitive coping skills and advice on economic self-sufficiency. 47 patients were randomly assigned to either the program or a waiting list. Results indicated that overall quality of life had significant improved in the treatment group, a remarkable finding, since trials on cognitive behavioral therapy or graded exercise therapy, often fail to improve quality of life in ME/CFS patients.

In 2008 Jason et al. assessed the envelope theory in a large sample of 114 ME/CFS patients. Energy quotients were measured by dividing patients estimated energy expenditure by the energy level they perceived to have, and multiplying this by 100. Findings were in line with the envelope theory as the energy quotient was correlated to numerous indicators of functioning, such as depression, fatigue, quality of life and disability. 81 of the 114 ME/CFS patients were assessed at a one year-follow up. Those who that had stayed within the energy envelope had had significant improvement in physical functioning and fatigue.

In 2017, the Jason research team tested the envelope theory in an even larger sample of 429 ME/CFS patients. Participants came from different location with two samples from Norway, one from Newcastle in the UK and another sample recruited online or by phone (in this sample the diagnosis of ME/CFS was self-reported). Patients were categorized by available energy and energy quotient. Results showed that patient who were overexerting themselves had similar levels of symptoms severity as those with lower available energy who stayed within the envelope. Another study by the DePaul group stratified patients according to illness trajectory. The subgroup (15,9% of the sample) that reported constantly getting worse, had higher energy quotient scores indicating they were overexerting themselves more than the average ME/CFS patient.

Longitudinal data that supports the envelope theory comes 44 patients that were followed up after a trial on non-pharmacological interventions in ME/CFS. Before the intervention their energy quotients were assessed. Findings showed that those patients who stayed within their envelope, had significantly more improvements in fatigue and physical function after treatment.

Sometimes staying within the envelope doesn’t work
In 2013 the Jason research group published results of a cluster analysis of the 114 ME/CFS patients used in earlier studies. Results showed that there was one group (Cluster 3) of patients with highly impaired functioning and post-exertional malaise, despite staying within their energy envelope. According to the authors, “this suggests that adaptive coping strategies were not associated with improved health.”

More emphasis on doing less?
Some have argued that the envelope theory should put more emphasis on reducing activities, as most ME/CFS patients will overestimate what they can and underestimate the detrimental effects overexertion has on their health. ME advocate Gabby Klein, for example, wrote: “My treating physician -  Dr. Enlander - always told me to do 50% of what I think I can do. It was the best advice I got. There is much more potential harm from activity/exercise than from rest.”  These arguments are supported by the average energy quotient found in Jason's research. In one study for example, this quotient was 239; meaning that most patients were overexerting themselves and underactivity was rather rare. In fact, Jason had to redefine the ‘envelope’: instead of a score of 100 - the point where energy availability and expenditure are balanced - a score of 150 was used since few patients had an energy quotient below 100.

Learn more

 * 2009, Solve ME/CFS Initiative - Managing Your Energy Envelope by Bruce Campbell (pdf)
 * 2013, Conserving Energy and Coping Work in Chronic Fatigue Syndrome Except When They Don’t: Study Suggests Large Group Gets No Help by Cort Johnson for Health Rising
 * 2014, "Play-Up & Lay-Up" not "Boom & Bust" - Sally Burch

Experiences of patients using the envelope theory:

 * The Just ME blogger, Sally Burch, has written about self-pacing and the energy envelope in a post called "Play-Up & Lay-Up" not "Boom & Bust".
 * Bruce Campbell, PhD, has included the Envelope Theory in chapter 7 of his manual, Recovery from Chronic Fatigue Syndrome: One Person's Story
 * The concept of staying within one's "energy envelope" is a similar pacing technique to the spoon theory.

Notable studies

 * 2008, The Energy Envelope Theory and myalgic encephalomyelitis/chronic fatigue syndrome (Full text)
 * 2013, Energy Conservation/Envelope Theory Interventions to Help Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (Full Text)
 * 2017, Energy envelope maintenance among patients with myalgic encephalomyelitis and chronic fatigue syndrome: Implications of limited energy reserves (Abstract)