AT LEAST ONCE a year somebody seems to produces a piece of research decrying the supposed benefits of running shoes. Shoe companies don’t help matters by indulging in some spurious claims about their footwear and, for the most part, resist independent scrutiny of how their cushioning technologies are tested.
In the absence of reliable data, mechanical engineering student Nicci Daly from Dublin’s Institute of Technology, Tallaght, recently decided to put four popular brands sold in Ireland to the test.
Daly is an international hockey player who suffers from shin splints frequently. She used a drop test rig – essentially a mechanical leg fitted with a prosthetic foot – to assess how well the shoes absorbed the impact forces generated by walking and running.
Without getting too technical, the test measured rates of de-acceleration – a standard measure of impact – as the foot hit the ground. To simulate the different impacts of walking and jogging on the lower leg, the four shoes were dropped from various heights.
The shoes chosen ranged from a low-cost Dunnes Stores shoe called Timeport (retails at €18), to the costlier Adidas Uraha 2 (€50-€60) and Reebok Reezig (€100) and the top of the range Asics Kayano (€140).
At a height that simulated a low-impact speed or walking pace, all four runners acquitted themselves well enough, with no noticeable benefits to choosing one over the other.
At higher impact speeds, closer to those of jogging or running at a medium pace, the Timeport runner was significantly outperformed by the other three, appearing to justify the need for a more specialist shoe.
Surprisingly, while the three specialist running shoes did better, the difference in performance between the three was found to be negligible, despite a hefty price variation of nearly €80.
The difference between all four shoes was negligible, however, when she changed how the shoes hit the ground away from the conventional flat-footed heel strike, which is how most of us run, to a more forefooted land or toe strike.
“Everyone’s biomechanical structure is different. If you suffer from over-rotation of the foot during running, shoes like Asics may help correct this,” says Daly. “However, the tests show that if you have good biomechanics and a forefoot strike, you won’t really need the stability and support supplied by the more expensive shoes.”
According to Stephen Tiernan, the lecturer in ITT’s department of mechanical engineering who supervised Daly’s project, what the research indicates is that a person’s running style is far more important than their shoes.
When jogging, 86 per cent of people heel strike, according to recent US research, incurring high-impact forces up the lower leg, says Tiernan. This necessitates good heel protection with high-density foam.
However, as the pace gets faster, people tend to change to running more on the front of their feet or toe striking.
“When you toe strike, your foot and ankle act like a spring, removing the sharp spike of impact forces up your leg,” explains Tiernan.
However, the conventional running shoe is constructed in such a way as to encourage people to run more on their heels, which may ultimately cause more injuries, he says.
The team’s findings appear to support the theory that African athletes can run barefoot on hard surfaces without suffering injuries because they land more to the front of their feet.
Changing your running style is not something that most people can achieve overnight, however. Most experts favour a gradual approach, warning that a sudden change away from heel striking can bring on stresses and strains of its own. There is help for those who want to learn how to change their running style.
Former champion athlete Catherina McKiernan, for example, teaches classes aimed at improving the biomechanics of running. (See catherinamckiernan.com). She says people’s feet have become lazy. “By heel striking you’re stopping yourself with every stride and then having to push yourself forward again with your toes,” she says.
The optimal style, and the one that causes the least impact on the body, involves landing mid-foot, just behind the ball of the foot.
“Your feet should land underneath you and not be reaching out in front so that your centre of mass is ahead of your foot strike,” McKiernan explains.
“By running this way, slightly falling forward, you’re co-operating with gravity and putting less stress on the body rather than running back in an upright position where gravity is pulling straight down on your body.”
McKiernan says the transition to running barefoot is too drastic a step for most and advises people to choose a light neutral shoe.
“What I recommend to people in terms of shoes, is to go into a shop and try on a few pairs and what feels comfortable is the way to go.”
What’s becoming clear in the running shoe debate is that the mechanics of running, and in particular what happens to our lower legs when we run, is less than obvious. There is a lot to learn.
