Wednesday, 19 June 2013

How the foot works.

How the foot works:
The foot is a mechanical masterpiece, it has never been re-created by man even with all the computer and technological power that we possess. This wizardry comes from the harmonious link between the 3 “separate” systems Nerve, Muscle, Joint.
The sub talar joint is one of the major reasons that an artificial foot is so hard to produce. With its infinite axis and complex articulations it is the key to the body’s ability of shock transfer. When the foot hits the floor we experience ground reaction force (shock). This force is the very reason that the subtalar joint exists, pronation is our protection against these repetitive shocks or loads.
We Need Shock:
We have developed the ability to pronate not because we want to be rid of shock but to have the ability to control it. Shock is a major player in allowing the pelvis and spine to move properly, this shock could otherwise be explained as a pulse or signal that de rotates the pelvis and spine and evokes tensegrity in our structure (Gracovetsky 1988)
There is no discussion that we need to heel strike when it comes to walking, the interesting debate starts when we bring speed into the equation. With an increase in speed comes an increase in the potential forces that you might encounter. So when we run we put larger forces through the body and this is something the body has to adjust for. Everything in the body is kept in an exact balance, tip that balance and at best compensation is needed, at worst injury or disease can present its self. This pulse from the foot to the pelvis is no different, it has to be just enough to de-rotate the spine and pelvis but not too much so that the knee and hip have to dissipate the excess.
This pulse is also our major economiser, it allows us to switch between our muscular and fascial systems to save energy and maintain a constant work load. This oscillation between muscle and facia is achieved by the pelvis and spine receiving the perfect pulse from the heel strike.
We do have a time when a forefoot strike is perfect. Sprinting is a high power low duration gait that will require us to run on the forefoot. The stretch reflex of the gastocnemius and soleus muscles along with the ridged supinated foot allow a large amount of power to be generated. This form of gait obviously does not produce the pulse needed to de-rotate the spine, requiring extra muscular effort to do so, but this is immaterial as the duration of the activity is only around 10-20 seconds.
So we have the 2 extremes identified. Walking is a heel strike and sprinting is on the forefoot. The big debate is what technique should the middle and long distance runners be using? There a little research out there at the moment that point to a forefoot strike and there are others that point to the heel strike.
The forefoot strike is being named as the most efficient way to run and for some populations this is probably true. If someone is lacking the ability to pronate then they will need to have another form of shock absorption, this is where the forefoot style can be used to reduce ground reaction force by the ankle joint plantar flexors acting eccentrically.
However to suggest that forefoot striking is right for everyone is a challenging concept. Is one technique ever suitable for anyone? When looking at the research published in support of forefoot striking, consider whether the authors or the organisations who pay for the research, have anything to gain from the results. If you go looking for something you are guaranteed to find it.  To reduce bias the study should include 'outside un-bias researchers' performing the full methodology of the study.  If the outcome is the same, then the study is known to have inter-rater and intra-rater reliability and any less is merely commercial hype and too much of this exits in the fitness industry and some of it refers to the forefoot striking research.
Another variable that is not taken into account in any study that we have come across is that of intrinsic biomechanical dysfunction. Dysfunction in the pelvis for example could lead to a functional difference in leg length, this has been shown to be a predictor of injury1. So was it the type of foot strike or the dysfunctional pelvis (or one of the many other intrinsic biomechanical issues that can present) that led to the results gathered in the current research out there?
The best coaches see what the athlete’s body is doing naturally and then refine their technique to suit their natural running style rather than fit everyone into the same box. From a coaching point of view, we need to recognise that the brain has the most amazing ability to make decisions to allow us to move our body and to compensate for any abnormal movement patterns and some biomechanical problems. If we attempt to artificially change its instinctive genius we can easily disrupt the body’s ability to control movement.
The take home message from this is that there is a lot more work needed in the field of research on this subject. There are as many arguments for forefoot striking as against, and while forefoot striking certainly is suitable for some runners who’s intrinsic biomechanics suit that style, there are others who clearly do not.