I love this topic. It's one of my favourite bug bears. 'Your feet are too flat'. 'You need arch support'. 'If you don't treat that, your arches will drop'. 'We can build your arches up'.
What a load of complete BS. This sort of science belongs back in a era when the concept was used as a determining factor for admission into the Armed Forces during the Second World War.
There have been a large number of studies that have investigated 'foot posture' and it's relevance to injury rates. There is no correlation between injury rates and flat feet in most instances. Indeed there are some studies that indicate injury rates in certain activities are actually more prolific in cavoid (high arched) foot types against their more planus (flat) incarnations. https://www.ncbi.nlm.nih.gov/pubmed/16130646
Lets address each of these statements individually.
Your feet are too flat. This would suggest that their is a normal or perfect foot type (there isn't). It simplifies the assessment of mechanics down to a purely static visual assessment rather then as part of a thorough investigation. It also creates an arbitrary ranking system where every clinician's opinion drives intervention. Many of the world's best athletes have planus feet and excel in their sport.
You need arch support. I love this one. Do your arches need some form of guidance counselling? A support group of sorts? Anyone who has passed through The Pedaler Podiatry would have seen first hand our reluctance to use this arbitrary term. Orthotics don't 'hold feet up' so as a consequence, popping an orthotic into their shoe won't provide the theoretical 'arch support' they require. An orthotic is simply an inert material placed inside your shoe that your foot lands on. It doesn't push back. It doesn't stick to your foot and hold it up.
If you don't treat that, your arches will drop. Umm, no. No studies support this theory. The key driver of intervention should always be pathology, pain or function impairment. Treating based on the assumption that not treating will cause the arches to drop further is inaccurate.
We can build your arches up. Holy cow. Firstly, why? Secondly, how? We know that flat feet don't cause any more problems then more cavoid versions, so why are we doing this? We also know that putting orthotics inside shoes won't lift the arches over time either.
Now, don't let my cynical musings convince you of other false generalities. There are exceptions to every rule. Human anatomy and mechanics are not simple structures. There are examples of planus feet that may require treatment, as there is when dealing with cavoid feet. There is also a place for orthotic therapy when required within this space especially when dealing with pain or imperfect function. In these instance, the use of an orthotic insert may assist in shifting load from overloaded tissue or changing the length of time a structure undergoes load.
Orthotic therapy can achieve pain relief, but if your about to prescribe it, you better have a better reason then - your feet are too flat.