We often speak of conceptual evidence vs. randomized double blind (participant and reviewer and blinded to groups) trials as different levels of evidence. Another piece to this is concealed allocation, that is where the person on the front end randomizing the groups is blind to the group they will go in. This may sound simple but if I am doing an injury trial and want a good result, I may be influenced to assign a participant in the group to help the desired result.
Example if we are doing a trial on injuries and footwear and I want to show less shoe is better, then naturally I’d like to see a runner in the footwear group who seems to have less risk of injury. So even if he or she doesn’t know which group they will be in, and the reviewer does not know….you see there can be bias creep.
There are many challenges to randomized trials on running injury, running form, and footwear. We have not even defined injury yet. We have not defined any gold standard form either and likely we never will.
For example there is a ton of knee and hip arthritis is shod runners and walkers. Barefoot societies do not get this condition. Doctors do NOT consider arthritis as a running “injury”. They say “Oh well…that is just life”
Maybe not. Maybe there is more to arthritis and degenerative injuries than just the bad luck of aging
There is conceptual evidence that landing midfoot and flat (which there is less impact transient, less accessory torque and muscle activation, and weight where it should be over sustanaculm tali of foot) will give less injury. It makes complete mechanical sense and runners who run this way rarely if ever get hurt.
So these are my replies to folks asking for “evidence”. There is hard scientific work being done now by Irene Davis of Delaware, Dr. Dan Lieberman, Jay Dicharry of UVA, and others showing that everything is out of natural alignment when you put a heel up. There is conceptual evidence that if all this is screwed up over years it is not a good thing.
Randomized injury trial of footwear? this will not be done. takes too long, hard to randomize and control, we do not know what an injury is, no funding, and no interest in running shoe industry to do it.