Often times in research we focus on norms. We look at the average effect of different interventions and then apply them to everybody. In this way, as a whole we get what the effects are for most people. By doing this, sometimes we miss the individual effects. So in today’s first blog of 2013, I want to share with you some data on the effects of running shoes on data with one individual athlete, Jackie Areson, who runs professionally for Nike.
In this data, what we did was stick her on a treadmill running at the same speed for every trial and set up my poor man’s high speed video analysis system (Casio Exilim + free motion analysis software), and took side and back views of her running. What I was looking at was a comparison of shoes impacts on her mechanics. Using barefoot as the “normal” and comparing from there. We looked at all sorts of different Nike shoes (because that’s her sponsor), her old shoes she trained in in college (Brooks Ravena) and then just for the heck of it, each shoe with custom orthotics and without custom orthotics (she does NOT wear them) to see the effects orthotics had on her mechanics.
So what you’ll find below is a chart comparing I’ve included pictures below for you guys to take a look at that give a good indicator of things and includes a few other shoes not included in the chart (because remember, this data is analyzed the old fashioned way so it takes a while to analyze it all!).
|Orthotics?||change||Change (deg)||Degree||Ground Contact||Flight Time||Footstrike||Heel-toe drop|
Footstrike degree- 90deg= knee and ankle of foot are at 90deg angle. So greater the degree, means further out ankle is in front of knee at footstrike. (Heel toe drop is using data from outside sources, not measured)
Pictures of shoes at footstrike- NO Orthotic on left. Orthotic on right (except for Nike free, Katana, and streak XC- NO Orthotics on those)
What did we find with Jackie.
- Orthotics almost always switch to a more pronounced heel strike (probably for a few reasons- They add weight, bulk, and increase the heel to toe drop.
- Orthotics don’t decrease pronation really, and don’t have a uniform effect across shoes. They tend to change things in different degress.
- Footstrike is greatly influenced by shoe type. It’s hard to pick out definite trends, but the less heel-toe drop the more likely she lands forefoot or mid/whole foot. Additionally, the lighter the shoe the more so. Interestingly (and the data isn’t up there) but for some reason she lands more whole foot with the Brooks Ravena then with comparable shoes in terms of heel/toe drop and weight. My guess is because of the high toe spring changes her loading/landing pattern (because at this period of time, she protected her past foot injuries by not “pushing off” her big toe.) Also, the contrast between flats and shoes is remarkable.
- Using the simple measure of ground contact time tells you how minimal a shoe is. It’s a kind of “duh, that’s obvious” conclusion, but a simple measure of comparing barefoot ground contact time versus shoe GC might be a useful measure. The difference (at the same speed) could give an indicator of how much the shoe “interferes”. So maybe a simple yet effective measure might be change in GC with each shoe? (Just hypothesizing but how cool would it be to go to a shoe store and run barefoot, get a GC, then compare shoes effects on it, instead of doing pronation junk?)
- Pronation- It varies. And having junk in your shoe to stop it really didn’t do much at all for Jackie. (and yes, pronation is natural, I just included in this analyse because it’s easy to measure, everyone measures it, and I wanted to show the effects shoes had on it…)
Hopefully this data makes you think a little bit and gets you to see the individual differences that shoes create.