More shoe foam may mean more problems.
Last night we had a great online teleseminar (www.onlinece.com). The talk was minimialism. Here was 2 of our take home points:
More foam in the shoe is not always good.
“Shoes with cushioning fail to absorb impact when humans run and jump, and amplify force under certain conditions, because soft materials used as interfaces between the foot and support surface elicit a predictable reduction in impact-moderating behavior. ” -Robbins
Basically barefoot feet, and even shoes with thinner foam/soled shoes, tend to judge impact more precisely because there is less foam to dampen proprioceptive input. The more foam you stack under the foot, the more material that must be deformed before a sufficiently rigid surface can be detected by the foot. Think of this, what do we do in rehab ? We stand people on stacked foam to give them an unstable surface (if they have championed balance challenges on a stable surface first, this is an important first step). When the foot cannot find a firm platform it searches for stability and drowns in the instability. This can be what more foam under the foot provides, inability to reference stable ground surface can negatively impact proprioceptive joint and tissue receptors.
2. Impact loading behaviors.
if we know the surface (the shoe or the actual surface/ground) is unstable, we will modify the pending impact loading behavior. In other words, you will jump differently onto a frozen puddle than you would dry ground. Studies have shown that the more foam a shoe has (ie. the more the potential instability from the example above) the greater the reduction of impact moderating behavior.
Humans reduce impact-moderating behavior in direct relation to increased instability.- Robbins
hope to see you in the next online teleseminar in 4 weeks !
shawn and ivo
BioMechanics April 1998
Materials: Do soft soles improve running shoes?
Most athletic shoes advertise injury protection through “cushioning,” but real world studies have not shown impact moderation.
By Steven Robbins, MD, Edward Waked, PhD, and Gad Saad, PhD