Capacity and Demand

I discovered this concept while running some frailty prevention events with my wife.

It’s a model about physical function, which I translate to psychological function. It emphasises the importance of awareness of our limitations and surroundings, developed from Joanne Elphinston’s “functional windows” (2015), which highlights functional capability and risk of injury.

When our capacity is greater than the demand placed on us, we are at low risk of poor outcomes, e.g., a 70 year old man asked to get a can of beans from a cupboard above him. This demand is smaller than his capacity – little risk.

When the demand placed on us is greater than our capacity, we are at high risk of poor outcomes e.g., the same man climbs to the top of a two story ladder and stretches over to clear the corner of the gutter. The demand on his balance, strength, flexibility and control is very high, putting him at great risk of injury and trauma.

The same principle applies to our psychological and emotional wellbeing.

(see images below)

When placed in a context where the demand is beyond our psychological capacity, we might experience discomfort, disorientation and distress and feel overwhelmed, anxious, or even traumatised. It’s unlikely that we would respond fittingly, leaving us dealing with unwanted thoughts of self-doubt, inadequacy and failure. The demand is greater than our capacity to handle the situation and remain regulated and grounded.

In the work environment, this kind of scenario can occur when communication channels are inadequate. For example, an onboarding process lacks thoroughness and a new employee feels thrown in the deep end and embarrassed when given a task without enough training, or a person is promoted beyond their capacity and left without enough support to grow into the role.

When a dysregulated boss vents at their team, some team members are fine, while others, through no fault of their own, may experience it as extremely distressing. A 2020 study (Leone, 2020), sampled 341 LinkedIn participants asking them if they were less stressed when their boss was on vacation, absent or called in sick – 88% said YES, admitting they spent 10% to 52% of work time withdrawing, avoiding the boss, networking for support and ruminating.

Daniel Priestly (2020), in his book “Oversubscribed”, shares how the demand of running three campaigns back to back in a short period, despite the financial success, left the team shattered with three important people resigning. He changed the campaign schedule accordingly.

As leaders, it’s in our interest to recognise our teams’ (and team members’) capacity to handle the demand placed on them. Failure to notice and respond with support/training/mentoring leads to team members leaving. I’ve made this mistake and lost good team members because of it.

An interesting observation I will cover in another post is that healthy growth occurs when the demand placed on a person or system is well measured. Getting this right is a key to great leadership.


Elphinston, J. (2015, September 22). JEMS Functional Window with Joanne Elphinston [Video]. YouTube.

Leone, P. (2020). Measuring the Impact of a Bad Boss. [online] Training Industry. Available at:

Priestley, D. (2020). OVERSUBSCRIBED : how to get people lining up to do business with you. S.L.: Capstone Publishing Ltd.



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