It still astounds me how little most physiotherapists know about exercise. Many still do not know how to prescribe, progress or regress structured exercise well, and most are unaware of what parameters are more important than others to monitor, that’s if they even bother to monitor anything at all. So in this short blog I want to discuss just one single parameter of exercise; VOLUME and highlight why it’s important for physios to consider and monitor in some of their patients rehab.
Simply described the volume of an exercise is arbitrary figure that gives you a measure of amount of work done. In its simplest form volume can be monitored as load x sets x reps. For example a patient doing a 10kg dumbell shoulder press, for 3 sets, at 10 reps per set gives this exercise a volume of 300, eg 10x3x10=300. We can add the volume of each exercise to others done in an exercise or rehab session to give us the total session volume. So if this patient also did a 5kg lateral shoulder raise, for 3 sets, at 8 reps after the shoulder press this gives another exercise volume of 5x3x8=120 and a total session volume of 300+120=420. We can then add up the volume of each session done over a period of time, so if this routine was done by this patient 3 times in a week the weekly volume is 3×420=1260.
In my experience many physios are completely unaware of or underestimate the value in measuring and recording volume for some patients. This is a mistake and as a consequence many physios and patients are unaware if they are progressing or regressing with their rehab. Usually the only way most physios and patients gage if they are progressing or not is if they feel less pain or feel stronger doing an exercise, and these are good guides to show progress, but not always, as for most things we see it can take some time for pain and strength improvements to become apparent. This can mean that patients and physios often become demoralised and disheartened in thinking that the rehab or exercise therapy isn’t working or helping them when in fact it is.
If physio’s were to use volume more as an outcome measure they and their patients can see progress a lot sooner than just using other measures such as pain or strength levels. Basically for me volume of work done is a more sensitive measure of progress for a lot of patients as I often see this improve before any other significant changes in pain or strength are made or felt by the patient.
Volume > Load
However many physios and patients mistakenly think that increasing the load of an exercise is the real measure of progress or success. And yes again it can be a sign of progress, but its not the only one, and usually many physios and patients try to progress load way too fast and way too soon at the expense of volume. This is a mistake.
Let me explain further. If we use a 10kg shoulder press as an example again, and let’s say our subject has done the first session of this exercise for 3 set of 10 reps, so a volume of 10x3x10=300. But the next session they want to progress so they increase the load to 12kg, that sounds a good idea right? Well hold on, because now as the load is heavier the subject can only do 8 reps per set. So what you say? Well this 2nd session is now actually a lower volume than the previous session, eg 12x3x8=288 v’s 3x10x10=300. A difference of 12, which isn’t much innthe grand scheme of things, but they probably would have been better to stick with the 3×10 at 10kg and either added a few more reps or an extra set, both of these adaptations would have increased the volume significantly, where as increasing the load reduced it slightly.
What has happened in this example, and is a situation I commonly see in clinical practice is the subject has underestimated the effort of increasing the load and the volume of work has been sacrificed. This mistake is also often made when subjects underestimate the effects of fatigue and try do too many reps in one set.
Volume > Fatigue
Let me explain further by using the 10kg shoulder press as an example again. Let’s now say the subject tries to do as many reps as they can on the 1st set and manages to get 15 reps done. Great hey, that’s progress right? Well hold on again, because now as they went to fatigue when they come to do the 2nd set they haven’t recovered and can only do 7 reps, and on the 3rd set they can only complete 3 reps. This now means the total number of reps for this exercise is only 25 and the volume is only 250. Had they just stuck with doing 10 reps on the 1st set and not gone to fatigue they would have recovered better, meaning they could have done a further 10 reps again on the 2nd and 3rd sets, meaning a volume of 300 not 250.
Again most physios and most patients will not recognise this reduction of volume and think that because they have done more reps on one set, or are using a heavier loads they are progressing when in fact they could be regressing. Simply put exercising with too greater load or to failure/fatigue often comes at the expense of volume of work done in novice and inexperienced subjects.
Volume + Effort
However, not all volume is equal. Harder effort exercises done less can be better than easier exercises done more. One way to address this is by recording the volume of an exercise but also the subjects self perceived rate of effort or exertion during the exercise, what’s often called the RPE. This is a simple likeart scale of effort, 1=very easy to 10=maximal. If we take the volume of an exercise and then multiply it by RPE we can account for changes in load and fatigue and ensure that volume is not affected if effort is increased.
For example let’s use the shoulder press exercise of 10kg at 3×10 v’s 12kg at 3×8. As we said before the 3×10 at 10kg is a greater volume than the 12kg at 3×8, 300 v’s 288 and if both exercises are rated as the same RPE say quite hard at an 8/10 then volume has been sacrificed.
But, if the 12kg 3×8 session is rated at a higher RPE say a 9/10 then the volume has NOT been sacrificed as 300×8=2400 but 288×9=2592. And if we use the other example of when the subject went to fatigue on the first set and only did a volume of 250 as opposed to 300, if we again use RPE we may find that if the subject rates the effort of the first fatiguing session as being higher than the non fatigue session, this could mean volume again hasn’t been sacrificed.
So in summary, most physios suck at recording and monitoring patients volume and rates of perceived effort of their exercises. Most physios and patients tend to sacrifice volume for load or fatigue. This is only ok if the self rated perceived effort of the exercise session is taken into account. I would urge all physios to start trying to record more of their patients volume and RPE figures during their rehab. It is a nice simple way to monitor progress for you and your patient and it can show progress well before changes in pain or strength and help with motivation, compliance, and adherence. To get you started you can download and use this very simple exercise log I have designed and use often here.
As always thanks for reading, and remember to pump up that volume…