What are energy impairment and ELCI?

Introducing the key features of energy-limiting chronic illness (ELCI) and energy impairment and why we use these terms.


Energy-limiting chronic illness (ELCI) is an umbrella term to describe long-term health conditions in which severe fatigue – or rather energy impairment – is a key disabling feature. ELCI and energy impairment are terms that have come out of our participatory research and they are important to our advocacy work as a Disabled People’s Organisation.

Through our multiple surveys and focus groups among the chronic illness community, we found that, while different diseases have their own unique clusters of symptoms that impact differently on each person, the predominant and most restricting feature of many chronic illnesses is fatigue or limited energy, as well as pain. The term we use for this is ‘energy impairment’.

There’s a reason we call it energy impairment, and not just fatigue.

Fatigue in both medical and general contexts, is seen as a subjective sensation of tiredness that you can push through. Medical science unfortunately lacks the tools to differentiate fatigue in healthy populations, due to certain occupations for example, from fatigue found in chronic disease. But fatigue in chronic illness is qualitatively and biologically different from universal fatigue or tiredness. So the term energy impairment, is used to convey this difference, and to describe an objective loss of function or impairment, not a subjective state.

We use the label ELCI for conditions where energy impairment is a predominant feature.  It includes neurological, musculoseletal, auto-immune diseases, as well as obviously ME and fibromyalgia. The umbrella term ELCI now incudes Long Covid.

What can we say in demographic terms about ELCI?  The label ECLI is closely aligned to the impairment category of “stamina/breathing/fatigue”, used by the Office for National Statistics for social surveys on disability. Impairment of stamina breathing or fatigue affects one in three disabled people of working age. This statistic comes from a data set collected by the Department for Work and Pensions, called the Family Resources Survey. And yet this category of SFB, which is close to concept of energy impairment, is not used in any government research into disability employment rates. It is not mentioned in the design of employment support, nor is it accounted for in the Work Capability Assessment (WCA).

Energy impairment is much more profound and multidimensional than fatigue.

The key components of ELCI that affect work capability identified in our research are

  • the experience of ‘payback’
  • the presence of cognitive fatigue and dysfunction,
  • a fluctuating pattern,
  • in some cases, sensory sensitivity.

Living with energy impairment means having a very limited reserve of energy that gets depleted by the slightest activity, like a mobile phone battery that never charges more than say 20%. And this reserve is drained by both mental and physical tasks. Living with ELCI means we calculate the cost of every small aspect of daily living and ration out energy accordingly.

In terms of work, what this means is that the very act getting dressed and feeding yourself might be as much or more than you can achieve in any one day with your energy reserve. There is nothing left for travelling to a workplace, let alone getting through a working day. If you have less severe energy impairment you  may manage to hold down a job,. But you can only do this at a the expense of the social and leisure activities outside of work.


Energy impairment should be understood as a broad spectrum of impairment. Its extremes range from people who are bedridden and need support with self-care, to people who may be able to function at work and appear non-disabled on the outside but are fighting a battle for recognition of their support needs and paying a high price for working in the rest of their lives.

Payback is the idea that if you exceed the energy that is available to you, you pay a high price in terms of increased symptoms and increased impairment afterwards, for example being bedridden for days. In some diseases, where this is particularly acute, payback is known medically as ‘post exertional malaise’. This means the issue of whether we can or can’t do something is complex. We may even struggle ourselves to say with certainty what we can realistically do.



Energy impairment causes cognitive difficulties as well as restricted mobility. The cognitive aspect of ELCI is every bit as restricting as the physical side, and in many ways is harder to adjust for or accommodate, and much less well understood. Cognitive fatigue possibly has the biggest impact on work capability, and yet is not factored into disability assessments.



Fluctuation is a feature of ELCI. But it is a lot more complex than the idea that we have good days and bad days. With many systemic illnesses, symptoms do vary over a period of months, or weeks, or even within a single day. But our functional capacity also varies greatly according to how we use our energy within a day or week and the payback that results. And this means that for us disability is a dynamic experience, very different to stereotypical ideas about disability as a fixed state.



Sensory sensitivity is important to mention in relation to work. With some chronic illnesses, everything from harsh lighting, to background noise, to everyday chemicals in hygiene and cleaning products can exacerbate symptoms and create barriers to work.


Why use the label ELCI?

Because together we are stronger. Our research suggests that, whether someone has fibromyalgia, lupus, ME/CFS, MS or Long Covid, the issues they face with the benefit system and in the workplace are very similar. Rather than advocating separately, for one diagnosis at a time, we should join together as a large cohort of disabled people to have our voice heard.

As a first step towards social change we must demand that government departments collect data about, and develop policies for, disabled people with energy impairment and ELCI.



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