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Running shoes research
Do men and women run with completely different gait styles? If so, are those differences so great that female runners need their own distinctive running shoes?
Some experts point out that a key difference between the sexes is in the hips–which tend to be wider in women to promote childbirth. For example, female runners at the 1976 Olympics had 6 per cent wider hips than male runners, when width was expressed in relation to height. This increased breadth should cause women’s legs to slant towards the ground at a greater angle from the hip. According to recent research at the Biomechanics Evaluation Laboratory at Michigan State University, the end result is that female runners’ feet strike the ground more towards the outside portions of their shoe soles, compared to men. Since both male and female feet end up flat on the ground during footstrike, female runners’ more lateral landings may cause an increased inward-rolling (‘pronation’) action in their feet during footstrike.
Since a popular belief is that excess pronation contributes to a higher risk of running injuries, some experts contend that women’s shoes should be made sturdier on their medial (inside) aspects to resist this tendency of female feet to lurch inward. However, not everyone is convinced that this is a wise idea.
‘First of all, it’s important to realise that modem running shoes, even the ones equipped with ‘anti-pronation’ features, actually cause pronation–they don’t control it,’ says Benno Nigg, PhD, a renowned University of Calgary researcher and author of the book, The biomechanics of Running Shoes. ‘A runner–male or female–who pronates about eight degrees while running barefoot will often pronate about 20 degrees while wearing ‘anti-pronation’ running shoes,’ says Nigg. In other words, trying to control pronation may only make it worse.
However, the concern about limiting pronation is a bit of a moot point for Nigg. ‘We’ve just completed a study which shows that there actually no differences in the risk of injury between runners who have high, medium or low amounts of pronation.’ And separate studies confirm that women and men who run about the same number of weekly miles have a similar risk of injury, suggesting that female runners’ greater pronation (if it actually exists) is not a particular problem.
Taking a slightly different tack is Ray Frederickson, one of the Michigan State investigators. ‘Women’s shoes should have more support on the outside edges of the midsoles, because the outside is where the first impact with the ground takes place. Since the running shoe companies don’t reinforce the outsides of women’s running shoes, women’s shoes tend to break down fairly quickly along their outer edges. If women would take a close look at the bottoms of their well-used shoes, they would usually notice that the outside portions show the most wear. As shoes break down on the outside, they fail to provide adequate support, which produces plenty of potential injury problems, including stress fractures of the outside metatarsals,’ says Frederickson.
For their part, the shoe companies haven’t exactly rushed to produce special women’ s shoes with more medial or lateral support than men’ s models. In fact, the major companies seem to be taking men’s shoe models, colouring them pink, and announcing that they are women’ s shoes. In addition, the running-shoe industry has failed to take into account the fact that men and women may be anatomically–not just functionally-different in the foot area. Basically, women’s feet tend to be relatively narrower at the heel, according to recent research carried out by Mike Hawes, PhD, at the University of Calgary’s Human Performance laboratory.
Since women have little recourse but to purchase shoes apparently designed for men, they often compromise by buying shoes that are actually too small for them, in order to get a snug fit for their narrower heels. Unfortunately, this can create lots of problems at the front of the foot. ‘A female runner’ s forefoot may be too big for the midsole underneath it,’ says Tom Brunick who operates a shoe-testing lab in Naperville, Illinois. ‘As a result, the front of the foot is poorly supported, and the foot may be cramped so that other problems such as hammer toes, ‘curly toes’ and black toenails may develop,’ says Brunick. ‘The running shoe companies need to produce a special, narrower, last for female runners instead of using the same last they use for men’ s shoes.’
Another reality that the shoe companies have overlooked is that women are usually lighter than men. ‘A woman often weighs 20-25 pounds less than a man who has the same foot length,’ says biomechanics expert Ned Frederick, PhD, of the Exeter Research Laboratory. ‘This basically means that women need less cushioning in their midsoles (there is less body mass to support) and that women need shoes which are more flexible.’
Why do females require greater shoe flexibility? ‘High body weights increase shoe flexibility naturally,’ says Frederick. In other words, a Goliath-like male runner can make even the stiffest shoe bend like a thin reed. Since women are lighter, they have trouble getting their shoes to flex properly, in accordance with the natural motions of their feet.
It makes sense to patronise a shoe company like Saucony, which is noted for its narrow, female-friendly heels; the Saucony Jazz has been an extremely popular women’s shoe. New Balance also produces shoes with narrow widths, and Nike promises to introduce a female-compatible running shoe in late 1995 or early 1996.
However, don’t settle for a shoe which is okay in the heel but too tiny up front. ‘About 90 per cent of female runners buy shoes which are actually too small for them,’ says Brunick. ‘Make sure that the width of your thumb–not the width of the shoe-seller’s thumb-fits between the end of your longest toe and the toe box of the shoe, that the widest part of each foot doesn’t hang over the side of the midsole, and that there’s no slippage in the heel as you jog around.’ If you’ve found a pair of shoes that feels comfortable and can satisfy all three requirements, you’ve found shoes that should work very well for you.
distance running injuries and training errors