Life is like music; it must be composed by ear, feeling, and instinct, not by rule.

Saturday, January 5, 2013

In case you doubt the impact of running shoes . . .


What do Orthotics and shoes actually do? Looking at data from a professional runner (click here if you can't read this post)



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!).






PronationPronationFootstrike
Orthotics?changeChange (deg)Degree    Ground ContactFlight TimeFootstrikeHeel-toe drop
Lunar FlyNO
7
10
93.6
0.214
0.114
whole10mm
Lunar FlyYES
7
9
10mm
KatanasNo
9
10
92
0.195
0.128
midfoot4mm
Lunar RacersNo
9
13
93.4
0.2
0.123
whole7mm
Lunar RacersYES
9
11
98
0.209
0.119
Heel7mm
PegasusNo
8
10
100.7
0.214
0.104
Heel12mm
Pegasusyes
9
11
101.6
0.214
0.109
Heel12mm
VomerosYes
10
12
96.5
0.204
0.114
heel11mm
BarefootNo


93.8
0.195
0.119
forefoot
0mm









 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. 
 1. 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.

2. Orthotics don't decrease pronation really, and don't have a uniform 
effect across shoes.  They tend to change things in different degress.

3. 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.

4.  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?)

5. 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.

Thoughts, comments????  Mr. Magness always has good stuff to share 

. . . great job Steve!

Harry

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