I was almost not going to bother writing this as I thought that the so-called ‘wet footprint test’ was coming up less often, so more and more people are taking notice of it not being a good test on which to make a prescription of a running shoe. I did a Google search and used the search tools to restrict it to pages Google had found in the last month. OMG … I could not believe how many recent references there are to still using this test.
The wet footprint test is where you get your feet wet and then stand on something like a paper towel and then it reveals your arch shape. Perhaps you can see a low arch, neutral arch or a high arch foot from this. This is claimed as the basis of how your foot functions dynamically and should be the basis for the decision making when wanting to choose a running shoe (ie overprontion etc).
The ‘Wet Footprint Test’ is a furphy¹.
The evidence for prescribing a running shoe based on plantar foot shape has clearly been debunked by the work of Knapik et al in three studies². According to the three studies, if you prescribed a running shoe based on plantar foot shape, it does not affect the injury rate. Mind you, that is all they actually showed and some have taken this research to imply that the whole ‘pronation’ and running shoes paradigm is wrong. It may or may be wrong, but you can not draw that conclusion from this research. Foot pronation and supination has many components to it (eg calcaneal eversion, forefoot abduction, medial midfoot bulging, lower arch profile) and the wet footprint test only measures one of them. You can still have a ‘normal’ arch profile on the wet footprint test, but still have, for example, an everted calcaneus and an abducted forefoot (this is why the Foot Posture Index was developed to take all those components into account).
The reason that they probably found no impact on the injury rate is possibly the well documented large body of literature on the lack of a correlation between static measures of foot posture and dynamic function. However, it should be pointed out that many of the ‘static’ parameters used in most of those studies are hardly ever used in clinical practice. The emphasis today is more toward clinical tests, that are still static, but are more concerned with determining loads and forces driving motion rather than the amount of actual motion or posture of the foot.
Those fancy pressure measuring devices that you see in so many retail outlets are also the same thing and are only determining plantar arch shape. Just because they do it dynamically by walking over the platform with fancy graphics on a computer as opposed to the messy wet test on paper, does not make it necessarily any better for prescribing a running shoe. Its just a high tech way to determine the arch shape, which Knapik et al showed does not result in a reduction of injury if you base your running shoe prescription on that.
As always, I go where the evidence takes me until convinced otherwise, and the evidence tells me that the wet footprint test and its high tech derivations are not supported by the evidence (ie its a furphy).
1. A ‘furphy’ is Australian slang for something that is erroneous.
2. Knapik JJ, Brosch LC, Venuto M, et al: Effect on injuries of assigning shoes based on foot shape in air force basic training. American Journal of Preventative Medicine 38: S197, 2010.
Knapik JJ, Trone DW, Swedler DI, et al: Injury reduction effectiveness of assigning running shoes based on plantar shape in marine corps basic training. American Journal of Sports Medicine 38: 1759, 2010.
Knapik JJ, Swedler DI, Grier TL, et al: Injury reduction effectiveness of selecting running shoes based on plantar shape. Journal of Strength and Conditioning Research 23: 685, 2009.