Q: From my recent reading I gather that the tide of opinion seems to be turning in favour of thinner, less cushioned training shoes. I now run in Nike Waffle racers, which have essentially no cushion, and have had no problems so far. I am running mainly on trails. What are your thoughts? Will we start to see any movement in which lots of runners will train and race in thin-waffle or slipper-type shoes? Do you know of any world-class types doing it?
John Simmons

A: When we contrast 'more shoe' with'less shoe', it's important to think about two key factors which may vary according to shoe type:

1. vertical impact forces
2. the extent and speed of motion at various joints, particularly the ankle and knee joints.

Where vertical impact forces are concerned, the research is very clear. Intuitively, more shoe is better, but research fails to confirm this assumption, suggesting that in some cases less shoe leads to lower impacts. This, according to some researchers, is because runners do a better job of adjusting mechanics to soak up ground-reaction force when they don't have mattresses under their feet. Bear in mind, though, that some of this research measures forces in the tibia, so trends could be different in the feet and ankles.
When we come to consider the extent and speed of motion at the ankles and knees, which can be injurious when extreme, it's clear that minimalist shoes have the advantage. Thicker, softer shoes lead to unstable ankles, more pronation and supination, and a greater tendency in general for the ankle to tip over.
It is interesting that you mention trails, because research shows that surface has little effect on impact forces. Trails usually feel nicer to us, but are they really? Researchers again say that we adjust our mechanics as we move from hard to soft surfaces, and vice versa, so that impact forces vary little. There are problems with this research, though, in that forces are again measured at tibia in some cases, instead of at the feet or ankles.
In general, strong, efficient, experienced runners seem to have little trouble when they switch running surfaces or shoes. The novice runner, on the other hand, seems to have more difficulty making those adjustments. The novice runner is less coordinated and less strong, and if you take his mattresses away, he might get hurt by vertical impact forces. Of course, he might be less likely to be hurt by extreme movements at the ankles or knees, since less-thick shoes tone down motion. To make things more complicated, there are probably some runners - novice and experienced alike - who are more susceptible to impact injuries, and others who are hurt more by muscle and tendon strain associated with excess motion at the joints during gait.



It's unlikely that we will see a large-scale movement toward minimal shoes, because the majority of runners are very weak and un-coordinated and do not like the feel of them. They tend to buy what feels cushy and comfortable in the store and don't think long-term. (Long-term thinking would be:'these shoes feel terrible now, but they will help me strengthen myself, become more efficient, and race better four months from now.)
In Kenya, most Kenyan runners train on worn-out shoes, which are like minimal shoes, since the midsoles have lost almost all of their compression-set resistance. And, of course, the young Kenyans work out on the most minimal shoes of all - bare feet. Most Americans and Europeans just use thin shoes for their speed sessions.



Owen Anderson