They may have started out as being good for your feet, but exercise sandals are now fashion items that have been widely adopted by the stylish and glamorous. Gwyneth Paltrow favours Birkenstocks and flip-flops; Sarah Jessica Parker swapped her Manolos for Dr Scholl's while shooting scenes for Sex and the City; and the model Heidi Klum designs for Birkenstock. Manolo Blahnik himself is said to favour Earth shoes for casual wear, and Karl Lagerfeld has designed a black suede Scholl-style shoe for Chanel. But is there any real benefit to exercise sandals, or is this merely a marketing sop to our aspirations for a healthier life?
"Exercise sandals are no bad thing," according to the reflexologist and chiropodist Ruth Hawe, who says that women are still cramming their toes into pointed shoes, and coming to her with corns and bunions. "I'm really pleased to see women wearing more foot-friendly and foot-shaped shoes, because fashion shoes with heels restrict the activity of the muscles, tendons and ligaments in the feet and legs, tightening and shortening them," she says. "Even the humble flip-flop is of benefit to feet."
Have you ever wondered why the foot has 26 bones, 33 joints, and more than 100 tendons, muscles and ligaments? It is designed to work in a particular way, and protect your knees, hips and back from the damage of walking over 115,000 miles in a lifetime. An average day of walking brings a force of several hundred tons to bear on the feet, while an estimated 85 per cent of people regularly wear ill-fitting shoes, according to research carried out at the Homerton Hospital in London. Happy feet, happy face, goes the old adage, as discomfort in the body is reflected in tension in the face.
"Few people understand how important their feet are," says Dr Rav Naik, a GP and orthopaedic physician. "Your feet are the first point of contact with the ground and work as a shock-absorbing system, but if feet are cramped into ill-fitting shoes they can't do their job. Any footwear that restricts the activity of the small intrinsic muscles of the foot also reduces blood flow and nerve stimulation, and if the foot isn't working as it was designed to, it has a knock-on effect on the rest of the body. When you walk barefoot, all these systems work automatically, which is why many chronic foot problems clear up on summer holidays when time is spent on the beach.
"With fashion shoes, the combination of a cramped foot and the additional height of the heel tends to make you walk with longer strides to balance, and this makes the weight loading on the feet, legs and pelvis uneven, putting joints at risk. Often, the heel is positioned too far back on the shoe, aggravating the problem."
Undoubtedly, flat shoes are better for our feet. But styles vary enormously and some "healthy" shoes are better for you than others. In particular, whereas brands such as Birkenstock and Dr Scholl's are designed with comfort and health in mind, many shoes designed to look like them may have no benefits at all, and may even be bad for your feet.
Dr Scholl's exercise sandals
The original Dr Scholl started out in corn plasters and foot powders in the mid-1900s, and it wasn't until 1958 that the first contoured, beechwood-soled shoe was launched as an "exercise" sandal. It is designed to exercise the muscles in the leg as you walk, and improve circulation, while the toe grip allows the toes to flex between steps.
By 1968, four million pairs had been sold, and the shoes were adopted by Twiggy and Jean Shrimpton. But their heyday came in the 1970s - they were the perfect fit for the back-to-nature flower-power era. Their renaissance today probably owes more to their being worn by the likes of Cameron Diaz and Sarah Jessica Parker than a desire for healthy feet.
However, Ruth Hawe makes one proviso: "Bear in mind that any loose-fitting shoe makes the toes grip inappropriately, which can give rise to claw toes. Even Dr Scholl's, with their toe bar, can be a problem if it's in the wrong place for your toes."
The first flexible arch support, designed to mirror the shape of the foot, was produced by the shoemaker Konrad Birkenstock in the 19th century, but it wasn't until 1965 that his descendant, Karl Birkenstock, produced the first sandal.
The moulded walking surface of the sandals supports and distributes weight evenly. They're not unlike Dr Scholl's, but Birkenstocks offer the wearer a softer walk, as the moulded heel cups absorb shock, and the flexible cork and latex soles have more "give" than a wooden sole. They also avoid the inevitable clattering you can incur from a pair of Scholl's when you bash your ankle with the wooden sole. Now available in over 100 different styles, Birkenstocks are suitable for children and - if carefully chosen - can look cool on men, too.
"The style with the strap across the instep, as well as the toe, gives a better fit and means there is less need for the toes to grip inappropriately," says Ruth Hawe. "And for children, the heel strap is good."
The naturally upright posture of Brazilians on the beach so impressed the Danish yoga teacher Anne Kalso in 1957 that she researched and developed a shoe to provide "negative heel" technology. Noticing a correlation between this good posture and the deeper imprint in the sand of the heel, which reflected the benefit to the feet and legs of the yoga mountain pose, which flexes the foot by lowering the heel, she designed a shoe that emulates just that. This has a natural effect on the style of walking adopted - heel first, weight shifted to the outside of the foot, and then evenly through the metatarsal area into the ball of the foot and the toes. This, in turn, helps posture by realigning the spine and pelvis.
"Negative heel technology is good as it spreads the weight load more evenly through the heel, and creates extra movement in the ankle," says Dr Naik.
MBTs (Masai Barefoot Technology)
A Swiss engineer, Karl Muller, who suffered chronic back and leg pain, designed the MBT shoes in an effort to alleviate his pain and retrain the way he walked, and it worked. He had noticed that the Masai people, who walk long distances barefoot over uneven terrain, never suffered the same sort of back or joint problems as those in the developed West. His shoe consists of a 12-layered, curved sole, that forces the foot to utilise its natural movement, while engaging those muscles in the leg, abdomen and lower back that are designed to be used when we walk. Walking in the way that nature intended creates less wear and tear on the body, thus making them perfect for those with joint or back problems.
MBTs are the Rolls-Royce of exercise sandals. They allow the foot to work exactly as intended, to support the body, while the built-in instability ensures that your improved posture is all down to properly activated muscles. The equally wonderful by-product of this is that wearing the shoes is reckoned to use up five times more calories when walking, toning the muscles of the thighs, buttocks and abdomen, and reducing cellulite. Unfortunately, the price for beautiful legs has to be paid with some seriously unglamorous shoes, although the manufacturers are adamant that a more fashion-friendly version is in development. Meanwhile, painting your toenails helps to offset the Russian shot-putter look.
"MBTs use the negative heel technology, but take this to a pivot point that then curves forward," says Dr Naik. "This alters the weight loading from the point of heel strike, through the mid-foot, and rolling forward to the point at which the foot leaves the ground. It's the sandal that most closely emulates barefoot walking on uneven terrain."
Beloved of beach bums and surfers, these were relatively hard to find on the high street until recently, when Monsoon launched dozens of different styles in their Accessorize chain for a mere £10 a pair. Every high-street store has followed suit, along with kitten-heeled versions from upmarket shops such as LK Bennett. Saved from the unyielding leather varieties handmade in Greece for tourists, we can now choose from a wide range of comfortable flip-flops - the current craze is for Havaianas, the Brazilian version, which are cool in both senses of the word.
"Although very flat," says Ruth Hawe, "because flip-flops tend to be very flexible and don't require your toes to grip to hold them on, they are foot-friendly and allow the Achilles tendon to stretch as it should."
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