Biomechnaical assessment of sport shoes

London Olympics: GB athletes' barefoot protects

At the London 2012 Olympics medallists from Great Britain may be barefooted on podium after the British Olympic Association (BOA) took a tough stance over sponsorship. They have warned athletes might have to take off their sponsor’s shoes before walking out to the presentation dais. Sponsor of Team GB’s official ”presentation outfit,” Is Adidas and they are insistant all athletes wear the company’s footwear at all times during the Olympics, including on the podium. The only exception is that competitors can wear any brand of footwear during competition because it is classed as technical equipment. Leading agents of top-line competitors sponsored by footwear giant Nike have told the BOA their athletes would be in breach of contracts if they are forced to wear Team GB’s official ”presentation outfit.” Potential medal winners Mark Cavendish (cycling) and Mo Farah (runner), may collect London 2012 Olympic medals in bare feet to avoid contractual issues.

Barefoot Zola Budd in trainers

In 1984, 17 year old Zola Budd grabbed the headlines as the barefoot champion who broke the women’s 5 000m world record. She went on to break her own record twice, running barefoot. She was also twice the winner at the World Cross Country Championship in the UK and at the Los Angeles Olympics (1984) had the controversial collision with Mary Decker-Slaney (US) in the women’s 3000m final. Ironically the barefoot champion now promotes running shoes, albeit according to Budd, Newton running shoes, simulate barefoot running. At 45 years old, Budd is still a strong athlete and blisteringly fast runner and although she still likes to run barefoot she trains in trainers.

Barefoot Running

The barefoot running craze came in the wake of the popular book by Christopher McDougall, entitled, Born to Run. The author took reference to the Tarahumara Indians of Mexico who ran long distances barefoot. To be fare, speaking as a shoe historian, indigenous populations did not have the craft nor know how to make shoes to last and so running barefoot was a necessity which we will never know whether having running shoes available then would have changed the face of history. So his logic is somewhat flawed.

However this disappointment with technology came at a time when many people were generally disillusioned by the factious claims of manufactures (and scientists) that expensive sports shoes were good for you. The absence of record breaking performances at the Olympics confirmed to many: ‘shoes do not maketh the athlete’. In a bid to overcome this human failing many runners chose to avoid full fashion designer sports gear in preference for minimalist footwear. Others abandoned footwear altogether to run au, naturelle (feet, that is).

An elementary understanding of human locomotion confirms the difference between walking and running cycles. On flat surfaces heel strike is perfectly normal up until middle distance running where forefoot contact then supersedes heel contact. Things become slightly more complex over uneven and tilted surfaces. Traditionally the design of athletic footwear (up to running up to middle distance) has included a heel whereas sprinting shoes have no heel. The current barefoot running craze is driven by shoe companies crossing the barrier and looking to develop new markets for their products using new polymer technology. Lighter and more durable foot gloves are challenging the traditional shoe.

In a study published a few years ago by a Harvard professor (Daniel Lieberman), he looked at runners who ran with or without shoes. The collected data indicated barefoot endurance runners often landed on the fore-foot before bringing down the heel, while shod runners mostly had a rear-foot strike. They concluded raised and cushioned heels in modern running shoes may account for this running gait. Further analysis suggested barefoot runners generated less impact with forefoot strike than rear-foot strikers in shoes and the former had a springier step which implied more efficient use calf and foot muscles. Researchers were clear however the evidence did not suggest barefoot running suffered fewer injuries.
More recently another Harvard academic (Irene Davis ), reported her latest findings and according to Davis, avoiding heel contact during running can help reduce shock related injuries when wearing barefoot style shoes. The underlying hypothesis is wearing heeled sport shoes introduces an artificial ‘heel strike phase’ when the weight bearing limb is subjected to repeated high impact forces (the equivalent to two to three times body weight) and hence potential for repetitive injury.

In another injury, function and rehabilitation study published in the American Academy of Physical Medicine and Rehabilitation, researchers compared barefoot running to wearing running shoes and concluded wearing running shoes was seen to increase strain on weight bearing joints i.e. hip, knee and ankle joints. Disproportionately large increases were observed in the hip internal rotation torque (54%); and in the knee flexion (36%); and knee varus torques (38%) when running in running shoes compared with barefoot. Researchers were also surprised to note knee torque was higher in running shoes than values recorded in a previous study to determine knee torque during high-heeled shoes during walking. The authors believe these findings confirm the typical construction of modern-day running shoes provides good support and protection of the foot but also increases stress on the lower extremity weight bearing joints. Researchers believe this may be due to the elevated heel of the running shoe combined with the increased material under the medial arch.

For some these scientific studies are pretty convincing but it is important to know the test conditions for each research project, in particular to the claims made by the authors. Pressure analysis in situ (in viva) is complex and most studies involve (in vitro) or laboratory testing, usually on a treadmill. This can make extrapolation difficult. Most of the gait studies used involve small numbers and are not independent studies (sponsored by footwear companies) which further complicates the published findings. So the jury is still out.

However running across hard surfaces increases the risk of injury from sharp objects like broken glass or discarded needles etc. which would suggest a protective foot cover as an intelligent precautionary measure. Contrary to market rhetoric shoes do not enhance performance enhance and whilst we may be born to run (barefoot), sadly the ravages of age, illness and hard surfaces mean our choices are restricted. As we age and older adults take up walking and jogging it makes good sense to protect the feet from serendipitous injuries because of impaired immune systems and compromised circulation and nerve supplies. All of which can compromise life style disease such as diabetes. To that effect shoes which comfortably fit the foot and are appropriate to use over hard surfaces and duration would seem to make good sense.

Foot note
The American Council on Exercise (ACE), is North America's leading authority on fitness and the world's largest nonprofit fitness certification, education and training organization. The Council recently announced the results of a small, independent study conducted at the University of Wisconsin, La Crosse, Exercise and Health Program on sock-style shoes. The study found that while barefoot style shoes may be beneficial for some who suffer from chronic running injuries, they can pose additional risks if runners who do not adopt their correct foot-to-ground strike style.

Common leg injuries
Stress Fractures
Endurance athletes suffer stress fractures in the hip, the femur (thigh), tibia (shin) and feet. They are due to the repetitive impact and rotation caused by contraction of the muscles attached to them.

Compartment Syndrome
Exercise induced compartment syndrome is a condition that causes pain over the front and outer edge of the leg with activity e.g. Anterior Compartment Syndrome Posterior Shin Splints describes pain on the inner side of your leg, right where the calf muscle meets the big shin bone. If the pain is severe a stress fracture in the tibia may be present.

Ankle Sprain
Ankle sprains are common injuries that runners experience. Early recognition and treatment of this problem will help speed your recovery from ankle ligament injuries.

Achilles Tendonitis
Achilles tendonitis is a painful condition of the tendon in the back of the ankle. Left untreated, Achilles tendonitis can lead to an increased risk of Achilles tendon rupture.

Arch Pain
Arch pain is a common foot complaint. Repetitive strain often causes inflammation and a burning sensation under the arch of the foot. Treatment of arch pain often consists of adaptive footwear and inserts (orthoses).

Plantar Fasciitis
Plantar fasciitis is a major cause of heel pain due to inflammation to micro tears of the plantar fascia along the base of the foot. A tight, inflamed plantar fascia can cause pain when walking or running, and be found in conjunction with a heel spur.

Delayed supination
Pronation is a normal movement of the subtalar joint through the gait cycle. When this motion becomes prolonged, delayed supination can cause a change in normal mechanics of the gait cycle. Shoes and orthoses to reduce full range joint motion can be help reduced associated symptoms.

If you have any of these symptoms then please consult your own physician.

Adrian Quist, The godfather of designer trainers

The word sneaker was first used in 1875 and referred to an early croquet shoe, which was developed in the US. The modern sneaker made its appearance in 1917, with brown canvas tops and black rubber soles. Its manufacturer, the National India Rubber Company, first called the creation Peds, However the name was already registered for another product, so the "P" was traded for a "K" (for "kids"), making Keds. By the 1950s sneakers became associated with the merging teenage leisure market. They were cheap, hardwearing and suitable for sport and leisure activities such as dancing. Worn by high school students around the world they soon became the icons of youthful rebellion. Whilst their older sisters wore stilettos, the young fry were doing it in canvas topped shoes. Keds for girls and chucks for boys. Soon sneaker sole patterns were changing and. the vogue for circles and squares in the 60s was replaced by trendy herringbone patterns, in the seventies. Herringbone was the brainchild of Australian tennis player, Adrian Quist. He must have had something because he was the left-court half of the great Australian doubles team of Bromwich and Quist, They won titles in Australian, the U.S. doubles and, Wimbledon, before and after the war. The function of ridged patterns on the sole of shoes is to increase traction and help with stability. This is critical on soft surfaces when a tennis player to weightbearing on one foot while turn their body. In a time before synthetic polymers, ridged patterns would be the only means of performance enhancement. The Dunlop Volley was introduced in 1939 and has sold more than 24-million pairs as the evergreen of tennis shoes. When Quist went to America, he saw a boating shoe with a very unusual sole pattern. He convinced Dunlop, to put the sole onto a canvas shoe and the rest as they say is history. Sport crossover to fashion is common but seldom lasts longer than a short period. The kids in the seventies took to the green shoe with the herringbone sole even although it had lost a bit of market lead with the tennis fraternity. Despite being replaced in the eighties by grids of squares the Dunlop Volley continues to be popular. Not long after outsole designs began to incorporate manufactures logos and or fashion dashes distinctive to the makers. By the 1970's keeping fit set in motion a movement which affected all ages. Shoes needed to match the outfit and a hungry market was created. To keep demand high, the giants like Adidas, Puma and Nike produced what were virtually fashion ranges of sports shoes. This remains a major industry worldwide.

Smart football boots: New order

The adizero f50 has been dubbed the intelligent football boot and is powered by adidas miCoach . According to adidas the electronic soccer shoe tracks and uploads performance data to help improve the players performance. The boots have a cavity in the outsole unit which houses the miCoach SPEED_CELL™, which in turn captures 360° movement and measures key performance metrics including speed, average speed (recorded every second), maximum speed (recorded every five seconds), number of sprints, distance, distance at high intensity levels, steps and stride rates. On-board memory stores all the measurements during your game or training for up to seven hours and then wirelessly transmits the on pitch performance data to a tablet, PC or MAC. Other adidas technologies built in to the new shoe include the Sprintweb, which provides stability during high speed movements, Sprintskin, a synthetic lightweight layer to reduce the weight of the shie and Sprintframe, which uses geometrics and a new stud construction to balance between lightweight and stability.

The adizero f50 boots come with a Speed Cell™ and a smart device dongle miCoach CONNECT for iPod and iPhone as well as the miCoach CONNECT for PC / MAC. The boots weighs 165g and costs €245 ($330) and will be available at adidas retail outlets and specialist stores worldwide from November.

Adipure Trainers:adidas following the leaders

Adidas have entered the barfoot running race with the release of their first "barefoot" training shoe. Called, Adipure Trainers, it was designed to mimic the experience of exercising barefoot and serves as a cross between a glove for the feet and a traditional shoe. Adidas hopes to expand into the U.S. where fanatical runners and gym-goers love the minimum footwear. From a corporate perspective barefoot shoes make up a tiny fraction of the $22 billion U.S. athletic shoe industry, but it is one of the fast-growing categories. Sales have more than doubled in the past year to roughly $750 million, according to SportsOneSource. The practice of running in barefoot has not been without controversy with a significant number of barefoot shoe wearers reporting injuries. Manufacturers encourage runners to gradually make the switch form tradional runners to barefoot shoes. Rival, Nike is the world's biggest athletic company and has roughly 65 percent of the market. Vibram has about 10 percent of the market with its Five-Finger shoe, which encases each toe separately and has come to define the style.