Use it or Lose it

One of the core principles of my practice as a physio and approach to health generally can be summed up by the following acronym: S.A.I.D

This stands for Specific Adaptation to Imposed Demand.

Put simply, this means that you will adapt (or attempt to) to the demands placed upon you.  It’s why Olympians train at altitude and why the more you do something the better you get at it. It’s why exercise should be the core component of any rehabilitation or treatment programme because, done consistently, it’s the only thing that will prompt the body to change and adapt.

It’s very closely related to another principle you are already familiar with: “…use it or lose it…” and this is beautifully demonstrated by this picture:


The picture shows a cross-sectional MRI view of the thigh. Through regular use the 74 year old has retained muscle mass, while in the sedentary individual we can see significant loss of muscle and increased fat mass (AKA adipose tissue) due to lack of use.

Why does this matter?

Well firstly it shows it’s possible to maintain a good amount of muscle mass into older age by applying the ‘use it or lose it’ principle.

This matters because muscle strength has been shown to be an independent predictor of quality of life and mortality. That means that, even after accounting for other factors such as lifestyle and wealth, the stronger you are in old age the better your quality of life and the longer they you will live. This is why the World Health Organisation recommends everyone undertake two sessions of strength training a week.

It’s estimated that humans lose, on average, 10%, of their muscle mass per decade after the age of 50. This is part of the ageing process. However, as shown by the difference between the two 74 year olds above it is possible have a significant effect on this ageing process with regular exercise.

So how do to this?

The key is to apply the S.A.I.D principle by stressing your body the right amount. Too small a stimulus and nothing changes but too large a stressor and you risk injury or ‘overtraining’. You need to find the Goldilocks Zone!


Too find the ‘Goldilocks Zone’ you need to push yourself a little out of your comfort zone.
How do you know you’re doing it right? Your muscles should feel tired towards the end and after exercising. Aching for the next day or two is completely normal and indicates that muscles are going through a repair process in order to recover and adapt.

You need to get out of breath and feel some muscle fatigue. Strength training doesn’t have to be done in a gym. Anything where you move your body or weights against gravity enough to create some muscle fatigue counts!

So next time you go to remind an elderly relative to “take it easy” remember the ‘Use it or Lose it’ principle and the MRI pictures above. Perhaps pushing themselves a little harder would be better for their health than taking it easy….

Thanks for taking the time to read this far! If you have any questions please ask. If you found it interesting please send on to others you think might like to read. If you would like to receive more like it, then please use the link at the bottom to sign up!

I’ll leave you with this heart-warming video proving you’re never too old to exercise and have fun whilst doing so!