Putting Running Shoes to the Test – Part 1
June 8, 2011 Leave a comment
I ran my first marathon about six months ago, and survived the 26.2 miles without a single blister. I thought my shoes must have been some pretty magical kicks! Now, as I begin training for my very first triathlon (a local sprint tri here in Southern California), I have been thinking more about my footwear because of all the attention that barefoot running and the new style of rocker bottom shoes are getting. For a long time the “best” shoes all shared certain characteristics, but now more engineers, designers, and biomechanists are improving the “best” shoes in radical ways. As a physical therapist, I am particularly interested in how these new technologies impact the body, and I’m curious to see if they will allow me to run faster and safer than ever.
First a little about the foot! For being as complex as it is (26 bones, 33 joints, 107 ligaments, 19 muscles), the mechanics of the foot are beautifully simplistic. As we turn our foot out to make contact with our heel to the ground, the bones shift and align in such a configuration that they are moveable. In this position, the foot is prepared to absorb shock, which in running can amount to three to four times our body weight. This incredible amount of force is absorbed in a couple of ways. Some of the force is absorbed up through our body, and some of the force is stored as elastic potential energy (think of a loaded rubber band) in the muscles that hold up the arch (namely tibialis posterior) and the fibrous tissue lining the arch (plantar fascia).
After the shock of our step is absorbed and all of our body weight is fully loaded on our foot, we need it to perform an entirely different role. We no longer want a moveable shock-absorber; we now need a very rigid lever over which to launch our entire body. When we roll onto our toes at the end of our step, the bones shift into a new alignment where they are rigid and locked. In this position, the foot now creates more torque that propels our body forward.
The classic running shoe is designed to do as much of the work for our foot as possible. It absorbs shock for us, which provides more elastic “spring”. It also creates a stronger, more supportive sole, which strengthens the foot’s lever. This logic is not necessarily wrong, but the new running technologies are challenging the principles on which they stand. Foot injuries and foot pain among runners are still both very common, and many would claim that it’s even more common than it used to be.
So, what should a good running shoe do? I’m going to attempt to answer that over a series of blog posts. During my training, I will run in three very different ways: barefoot on soft and hard sand, with a traditional, supportive running shoe, and with my new pink ProSpeed SRR fitness sneakers. I will share the different biomechanics of each style as well as the advantages and disadvantages of each shoe, so that we can all run a little faster and avoid injury!
Written by: Maureen McClure
Maureen is a Doctor of physical therapy, active in running, swimming, and beach volleyball. She regularly trains for marathons and triathlons.