Running shoes: cause or cure?
MRC research shows that it's best to put your bare foot forward, as KEN DANIELS discovers.
New research into the human body's response to the impact caused by long distance running has given hope to many runners: from Sunday joggers to serious marathon contenders who have been plagued by running injuries.
Associate Professor Martin Schwellnus explains: 'It appears that running injuries may be avoided by alternating running barefoot with running with shoes and on a variety of different terrains. This gives the body the opportunity to "practise" the necessary adjustments to adapt to new situations.'
Anecdotal observations among rugby players had shown that, when the players ran barefoot along cross-country routes during their training, the incidence of injuries among them appeared noticeably lower.
So, after decades of investment in billions of rands of running shoes aimed at stabilising the foot to prevent injuries, research has shown that the human body has its own intricate and complex mechanisms to cope with the impact of running - as it has been doing for thousands of years.
The latest research being conducted at the MRC/UCT Exercise Science and Sports Medicine Research Unit has also given the lie to claims by footwear manufacturers that specially designed shoes can prevent injuries. Studies in the United States have revealed that so-called state-of-the-art running shoes that claim to prevent running injuries not only fail to do so, but may even cause damage to the wearer. The quest to prevent and treat running injuries has for the last three decades been the aim of sports scientists all around the world and huge resources have been allocated to the design of a running shoe that protects the wearer from the ravages of injury.
However, research being conducted by a team of clinicians, physiologists, and biomechanists at the unit has revealed some startling new data on how the body deals with the stresses of running.
Sketching the background to this team's research, Associate Professor Martin Schwellnus explains that, since the boom in jogging and long distance road running in the 1970' s, a huge amount of effort has been devoted to running injuries and how they could be avoided.
'The emphasis was placed particularly on running shoes and the role they could play in preventing injuries,' he says.
'At first running shoes were designed to provide maximum cushioning against impact, which was thought to be the major cause of injury,' Schwellnus says.
However, in spite of the continuous development of running shoes, the injuries continued unabated and sports scientists began looking at other factors that might be causing injuries to the knees and ankles of tens of thousands of runners. In this period of the development of the running shoe, the main focus was on the concept that the foot appeared to go through a rolling motion, which could be either inwards or outwards, shortly before landing. These are called supination (rolling outwards) and pronation (rolling inwards), but it was the latter movement that received most attention and was blamed for the injuries suffered by most runners.
This in turn spurred a frenzy among shoe manufacturers to create a model that would stabilise the foot during landing, prevent pronation and consequently put an end to most injuries.
'Unfortunately, this did not happen. Not only did the injuries persist, but in some cases they were exacerbated by the use of the new shoes,' Prof Schwellnus said.
It was during this period, when rigid running shoes were still being seen as the elixir for all running injuries, that a new way of thinking was beginning to develop.
Prof Schwellnus says it was then decided to give attention to the mechanisms that control the foot and how it landed during the running motion. He soon began to realise how accurate the genius Leonardo da Vinci (a renaissance painter, architect, engineer, mathematician and philosopher) was when he described the human foot as a masterpiece of engineering and a work of art.
Scientists in the United States of America began looking at the gait adopted by runners and the effect it could have on how the body absorbed the jolts it suffered while running. USA scientist Dr Nicholas Romanov developed the Pose Method of running, which suggested that the adoption of a correct body position during running could reduce impact and increase performance. This method of running was tested by one of the team members from the unit, University of Cape Town PhD graduate Dr Regan Arendse; it received widespread support and drew attention to new approaches in dealing with injury.
Prof Schwellnus and his team continued to study the human body in motion and to determine as accurately as possible the positions it assumes during a running stride.
This was done by attaching light receptors to key parts of a runner and then using a high-speed camera to film him while in motion on a treadmill. This gave the observers an impression of how the body frame behaves while running. After studying the gait of dozens of runners under scientific conditions, Prof Schwellnus and his team noticed that the body goes through a rapid, but complex, routine in every stride it makes.
'It is as if the human body has its own built-in suspension system which it can sense, and then adjust, in order to cushion an impact the foot might encounter. Before each foot strikes the ground, it appears as though the brain, or central nervous system, prepares a detailed programme to prepare the foot for the expected impact on the ground,' he said.
He compared the procedure to that followed by an airline pilot preparing an aircraft for landing. If the plane isn't properly prepared for the landing it would more than likely crash.
'Imagine a person walking down stairs in the dark. If the person thinks there are six steps, but there are in fact five, his leg will strike the ground with a painful, jarring blow because the leg has not been prepared for the landing - it was expecting to take another step down.'
Another startling discovery that Prof Schwellnus's team made is that, left to its own devices, the human body can cope very well indeed. In fact, the pronation and supination observed in the natural movement of the foot - and blamed for a myriad of ailments - are nature's way of dealing with the impact caused by running and are an intricate part of the body's suspension system.
But even shoe manufacturing companies are finally beginning to realise this, and an international sports shoe and manufacturer has recently launched a new model which it compares to running barefoot.
Finding the source of Achilles tendon injuries
Prof Schwellnus' research has shown that the foot is the first line of defence in cushioning the impact of landing. If the foot is injured, the knee might take over the role as a shock absorber by bending earlier than it should.
But, since this is the body's emergency procedure for dealing with immediate danger, it could lead to new stresses on other parts of the body.
This is the field of expertise of Ms Liane Azevedo, a researcher from Brazil who is working on her PhD in sports injuries at the MRC/UCT Exercise Science and Sports Medicine Research Unit.
Ms Azevedo has found that many cases of Achilles tendon injuries can be traced to the above scenario.
'If the foot has an injury or is unable to land properly because of a tight shoe or some other problem, the knee bends early to cushion the blow and this in turn stretches the Achilles tendon. So the initial problem might have been caused by an injury or pain elsewhere in the foot, but manifests itself in the Achilles tendon,' she said.
According to Prof Schwellnus, the research has shown that injuries could be treated more effectively if seen as being part of the overall movement of the body.
'By studying the movement of runners we are able to get a better understanding of how the body responds to the effects of running, how to prevent injuries, and how to treat them when they arise,' he said.
Contact Prof Scwellnus on (021) 650-4562.