09/03/2023

Good morning readers! I thought it would be interesting to follow up the topic of last month’s blog, about improving heart health with exercise, by looking at a founding principle Physiotherapists use when prescribing exercise for health related problems. Our exercise prescription approach mainly relies on the S.A.I.D. principle, which stands for “Specific Adaptations to Imposed Demands”. 

As Physiotherapists one of our mains goals is to identify tissues or structures in the body that are unable to perform the function needed so you can do what you want in a comfortable manner. For example, if you have some knee pain that prevents you from climbing the stairs, we may pick up that certain muscles are weak and therefore we need to strengthen them. The S.A.I.D. principle tells us that we need to apply sufficient demand on the muscles, so that they will grow stronger over time. 

Of course the demand on the muscles must be specific to the change being sought. For muscle strength, the exercise would likely require 3-4 sets of 8-12 repetitions. For developing power (explosive strength if you like), the exercise would involve 3-4 sets of 2-6 repetitions. While muscle endurance requires 3-4 sets of 15-20 repetitions. However, if you do not experience the feeling of demand in the targeted area of the body, towards the end of the repetitions for a set, then the specific change being sought will not be achieved. So you may be wondering “what should this demand feel like?”. Let’s talk about that next.

Returning to the example of a muscle strength/power/endurance exercise, generally the experience of demand should feel like some form of tiredness in the muscle. In my experience, people often use different words to describe this. It could be “burning”, “aching”, “dull”, “heavy”, “tried”, or any other term that reminds the person of a time when they worked their muscles hard, such as with climbing a steep slope, gardening etc. The second aspect to ensuring the demand is correct is that you feel it in the area you should. If you are not feeling it at all, then it’s likely the exercise is too easy and we need to add more weight or find a harder version. If you are feeling the tiredness in a different area of your body, then it may be that the technique is not quite right or the exercise is not suitable at that point in time. 

On a separate but certainly related note, it is possible that when doing an exercise we prescribe, that you may feel some of the symptoms that have brought you to see a Physiotherapist. We should be able to pick up on this when trialling the exercise with you in the clinic. I normally tease this out by checking:

• How strong is the symptom?
• Does it stay the same, improve or get worse as you repeat it?
• How does it feel after?

If the symptom is mild, say 2-3/10, remains mild or improves and is gone within a few seconds of completing the exercise then it will generally be suitable. There are exceptions of course. However, if the symptom is strong to start with, worsens with repetitions and / or lingers at moderate level after the exercise, then I would be inclined to change the approach. 

A final and very important aspect we consider as an exercise programme evolves, is how to make the exercises more specific to your goals. If we continue the previous example of knee pain with climbing stairs, we may start off with some exercises in lying to work the quadriceps muscles (at the front of the thigh). We may then progress to a sitting position with weight on the ankle and straightening of the knee, then to exercises with both feet on the floor and finally exercises with one foot on the floor or a step. 

I recognise that I have provided examples relating to muscle strength only, however, there are a number of other areas we as Physiotherapists, may seek to improve. For flexibility, you may expect to feel a tightness or stretch sensation with the exercise and the length of hold, number of repetitions, frequency in the day or week will all be important to getting the recipe right. If we identified that coordination or balance required improvement, the goal would for you to feel challenged in staying stable. You would gain little benefit from standing on one leg completely steady, therefore we may put something soft under your foot, make you turn your head side to side or close your eyes. If you need to improve your fitness, then walking, cycling, running etc at a level that doesn’t get your heart rate up sufficiently will not help you achieve the benefits. Some simple ways you can know if you working to the right level are if you are breathing faster, sweating, checking a heart rate monitoring watch. 

I hope that gives you a good idea of what the S.A.I.D. principle is and how we use it to select exercise to assist your recovery. 

Till the next blog, stay active and stay well!

Lonan Hughes

Chartered Physiotherapist