Runningmonkeys

If you have spent much time reading magazines and internet resources, no doubt you will have seen this recurring question. 

“I am looking forward to a personal best in …weeks time at the… race.  I was wondering if you thought that It would be safe for me to wear racing flats?”

This is such a hot topic for discussion amongst distance runners, that I am surprised more people haven’t carefully thought through the real issue.  When someone posts the question “Should I wear Racing Flats?”the same old answers surface.  

“You should wear racing flats if:

1. You run at a pace of at least… or expect to finish a marathon in … (fill in the arbitrary number for your self)
2. If you weigh less than … (take a guess at the supposedly safe weight for racing shoes)
3. If you have a history of being injury free (as if anyone is putting up their hands for this?)
4. If you are bio mechanically normal in foot plant style. (remember normal doesn’t always mean good)
5. If you are the sort of person who drives through red lights, jumps from moving trains or would donate their brain to someone who would use it more, if someone on a running forum tells you that it is safe (even if it doesn’t sound right)

Sorry, but I added the fifth item in by myself, but you get the point.  Are you sick of seeing the same rules of thumb and old wives tales.  Sure speed and weight and everything else are associated with your decision to wear flats, but they should not be the only factors that help you decide for yourself.  There is more to it than many people, including the running shoe manufacturers, would have you believe.  How about we go back to first principles and see what we discover.

First things first, why do runners wear shoes?

1. To keep our feet warm in winter and stop the sunburn in summer          
2. To protect our feet from sharp objects and biting animals                          
3. To protect the soles of our feet from abrasion and callouses over time
4. To keep our feet clean and looking pretty                                            
5. To give us something to spend money on (otherwise running is sooo cheap)
6. To enable us to define ourselves with extra brand names and logos (dubious value)  
7. To control the motion and movement of the foot while we run         
8. To cushion the foot as we run                                                                                   

The first 4 items are fairly common sense and apply more or less to each of us depending on the condition of our feet.  Numbers 5 and 6 are put there because they popped into my mind, not because they have any real reason to be there.  Numbers 7 is outside of the realm of this article today.  Number  8 is the point that we are looking at.

Secondly, what is the big difference between racing flats and cushioned trainers? 

The biggest difference is cushioning and weight.  The racing flat has very little cushioning and subsequently very little weight.  This means that we are able to swing it through the air more easily and so run a little faster.  On the other hand the trainer has a lot more cushioning which means a lot more weight and a therefore more effort for each step.  The cushioning is placed there to reduce impact shock and the injuries that happen as a result.  Reduced impact shock is also supposed to conserve energy and help us retain our normal form. 

However there is also another significant difference between racers and trainers that most people seem to ignore.  This is the obvious distribution of cushioning.  Take a look at the wall of your local running shop and look at the “angle” of all of the running shoes.  Racing Flats have very little stuff under the heel and so they look “Flat”.   The tallest trainers have up to about an inch of height between the runners heal and the ground, so they end up with quite an angle.

Some trainers tend to look more like ’70s hot-rods rather than running shoes with their jacked up rear and low down front.  Someone has put massive shiny chrome white walls on the back but left the stock standard skidders on the front, giving it a mean angle look. The back height varies dramatically, but if you look at all of the models available there is very little difference in “front wheel size”. 

Aesthetics aside, why would someone jack up the back of their running shoes?  This is where the rubber meets the road, or so they say.  The running shoe manufacturers assume that the vast majority of runners hit the ground first on the heel and then roll towards the toe.  This is probably a realistic assumption, that you can verify by watching runners you see out on the road.  This is a familiar and often natural form that was promoted for a long time as an efficient and safe running style.  Even I can recall, not too many years ago, advising friends that were starting out as beginner runners to use this style to keep themselves free from injury.  Most people find it easy to hit the ground with the heel and roll forward.  It seems to work, it feels OK and it looks like ”Real Running”. 

Here is the downside to conventional heel strike running.  Heel strike running puts a significant load on the point which is directly under the bones of your leg.  This force is transferred straight up through the rigid structure of the leg and into the knees, and it keeps on going.  Running shoe manufacturers realise that this isn’t a good thing, so they have continually and progressively developed ways to put more cushioning into the heels of their runners while still trying to keep some feel in them.  The result we see, is the high heeled trainer.  Shaped like a wedge, it is perfect for landing on the heel with a low front which is great for toeing off and bounding forward.  I can still remember the first time I bought some “high heeled” Nike Max shoes.  Stepping out the door for the first time I was astounded by the lean forward on the shoes.   Now these sort of shoes feel less spectacular but I can only assume that the angles are still at least as steep.

Compared to this, racing shoes are just plain basic.  They are stripped of anything except the bare essentials to fulfill the first 4 points in our “Why do runners wear shoes?” list but they practically ignore the motion control and cushioning.  The cushioning is very thin and usually just plain old lightweight foam (with a fancy trademarked name).  The sole is almost consistently thick along it’s length with none of it really very luxurious.  Racing shoes are a nightmare waiting to happen for a heel striker.  He/she will slam down on a sliver of very thin and often narrow foam and the impact will travel directly up through the leg.

This then gives us a definite clue as to who should be wearing racing flats.  If we hit the ground with our heels 180 times a minute, can we really afford to wear racing shoes with very little heel cushioning?  Especially if we’re talking long road races like marathons and beyond, is it sensible for a heel striker to wear shoes without full heel cushioning?

So who can safely wear racing flats?  The same people who can safely wear no shoes at all.  The same people who run fast and smooth and experience very little destructive road impact.  The sort of runners who land on the front half of their feet.

Front foot runners use the ankle joint as a spring to absorb the impact of running.  They are able to stop the shock from travelling up their legs by diffusing the energy before it does any damage.  Their legs are used like hinged springs rather than pogo sticks.  Their feet hit the ground like a kangaroo’s instead of like a pirate with two wooden legs.  These are the people who can safely wear running flats.  They can wear them whether they are running fast or slow.  They can wear them for 5k’s or in an ultra-marathon.  They can wear  them in racing and in training.  So here is the real story:

Heel strike runners need heel cushioning and forefoot runners do not. 

If you are a heel striker and you want to wear flats you can either just go ahead and wear them (but you should pencil an injury into your diary in the near future) or you should relearn your running and become a forefoot runner. 

Note: Fast runners with few injuries are usually forefoot runners.  They are able to safely wear flats.  But it is not their speed that permits the safety.  It is the fact that they run on their forefeet.