Gait Analysis: The Foot

[Guest guest]

SPECIAL FITNESS ISSUE: THE FOOT

OK, let's take a closer look at that stride

Gait analysis can help runners improve their performance -- and

reduce injury.By Shari Roan, Times Staff Writer

http://www.latimes.com/features/health/la-he-

gait1jan01,1,6570945.story?coll=la-headlines-health

Felix didn't realize running could be so complicated.

The high school junior took up the sport a few years ago and quickly

emerged as a top distance runner at La Mirada High School. But then

her coach had team members' gaits assessed.

The analysis, in which was videotaped while running on a

treadmill, showed a litany of problems. She shifted her weight to

the inner foot, which could lead to ankle and foot injuries. Her

arms swung too much, which could cause misalignment in her lower

body. And she had a heel strike, meaning the heel of her foot hit

the surface first, placing more stress on the heel and slowing her

down.

" I was really surprised by what I saw, " says , 16. " I

learned a lot about my form that I didn't know — that it matters how

your heel hits, where your arms are. When you have good form, you're

a better runner. "

And perhaps a less injured one too.

Long used in medical settings to help people with movement

disorders, such as cerebral palsy, learn to move more efficiently

and with more stability, gait analysis is increasingly offered in

running and footwear stores.

Casual joggers and walkers are using the analysis to find

comfortable — and productive — footwear, to prevent injury and

assess chronic injuries or soreness.

In general, gait analysis is the study of foot motion during normal

running and walking. The process evaluates the foot's anatomical

structure, muscle flexibility and strength — assessing how those

factors influence the way a person runs or walks.

Weak or inflexible muscles, if stressed by a lot of running over

time, can lead to injury. And even a simple movement such as an

excessive arm swing can make a difference in the performance of a

competitive runner, adding a precious second or two to running times.

" It shows you things from a biomechanical standpoint: What are you

doing when you run? What small improvements can you make? " says

Ferber, director of the running injury clinic at the University of

Calgary in Alberta, Canada. " But it also suggests things on the

clinical side, such as where someone is inflexible or weak in a

specific muscle. "

Several forces have merged to popularize the service in recent

years, such as more user-friendly video and computer technology and

athletic footwear that requires more thoughtful shoe fittings. At

the Running Lab in Orange, owner Earl Malit displays shoes by their

specific function — extra support, more cushion, added stability —

not by brand or price. The store also features a gait analysis lab

with a treadmill, video cameras and a computer to receive the

information and analyze it. " We don't just look at the foot, " Malit

says. " The whole point of gait analysis is to understand why you do

what you do. "

Watching your step

Gait analysis can be simple or highly sophisticated. Footwear stores

often offer the simplest method — a visual inspection of the foot

and shoe. More specialized stores and many physical therapy and

sports clinics offer video gait analysis, in which a person is taped

while running on a treadmill and their movements are studied. An

even more sophisticated method includes a digital analysis using

video- and motion-analysis computer software that can produce two-

dimensional or three-dimensional images.

" There are all sorts of gradations, " says Dr. Sheila Dugan, an

assistant professor of rehabilitation medicine at Rush University

Medical Center in Chicago. " The different types of gait analysis

assessments will give you different information. "

During a visual inspection, store employees typically examine

patterns of wear on the customer's old running shoes. " Shoes tell a

history if they're well-worn, " says Irene , a professor of

physical therapy at the University of Delaware. For example, a worn

heel can suggest a heel strike, in which the heel of the foot

strikes first instead of allowing a larger surface of the foot to

absorb the shock. Runners who land hard can develop stress fractures

more easily.

The customer is also asked to walk across the store so that problems

with knock-knees, splayed feet, pigeon toes or falling arches can be

identified. The foot should also be measured, Malit says, including

length, width and arch length.

In video analysis, a customer is taped from various angles. The tape

is then played back frame by frame to identify specific movements

not visible to the human eye.

underwent gait analysis because her coach recommended it.

Ralph Casas shepherded his La Mirada cross-country team to the

Running Lab last August and says he'll take his team back every year.

" The kids thought it was neat, " he says. " And it was helpful to us

as coaches because we could then tailor workouts and strengthening

exercises that would target what they needed to do. "

For example, gait analysis showed several of the girls, including

, tended to twist their upper bodies while running. (The

computerized video measurement even showed the angle of the tilt.)

Runners perform faster when their upper body is still. Moreover,

twisting of the upper body can cause the thighs to rotate in too

much. One common result of this abnormal rotation is a knock-kneed

appearance and kneecap pain.

" We still had our share of injuries this season, but they weren't as

debilitating, " Casas says. " The runners were stronger. "

Video analysis can also include use of a pressure plate, a device

that looks like a bathroom scale and gives information on how much

pressure each part of the foot absorbs while running. For example,

excessive pressure on the inside of the foot suggests an overly

pronated foot, which can lead to strain on the connective tissues

elsewhere in the foot. Ideally, pressure should be distributed more

evenly throughout the foot.

As for digital analysis, it's most useful in research settings,

Ferber says. " It's very technical, and the interpretation is

relatively complicated. " Digital analysis can yield information that

can be otherwise hard to detect. It can also show how the movements

in a runner's body are synchronized.

says she prefers video gait analysis rather than the

complicated charts and graphs produced in a digital analysis.

" When I sit down with the patient, they don't understand the

graphs, " she says. " But they can understand looking at themselves on

tape. They can see it when I say, 'See, your knee is coming in.' "

A digital gait analysis can cost up to $1,000 in a medical or sports

clinic. The cost of video analysis varies widely. (It's typically

more in a clinic than in a retail store.) Prices can range from $45

in a store to several hundred dollars in a clinic. Visual footwear

inspections are usually offered free or at a nominal cost. Health

insurance will sometimes cover gait analysis performed in a medical

setting if the purpose is to assess an injury.

Who should get one

Opinions vary on whether gait analysis is useful for everyone. Most

biomechanics experts agree that almost everyone can benefit from a

visual gait analysis to help them find the best running shoe. But

some experts think more detailed gait analysis is best suited for

competitive runners trying to gain a performance edge or for people

who are trying to figure out the cause of a chronic injury.

Research shows that at least half of runners sustain an injury over

the course of a year. Many are related to biomechanical flaws.

" The most common types of injuries we see in running are overuse

injuries, " Dugan says. " There is something not ideal about your

biomechanics. "

The most likely problems identified in gait analysis include an over-

pronated foot that shifts weight to the inside and strains the

connective tissues of the foot, ankle and knee. Over-pronation can

lead to falling arches, bunions, hammer toes and heel pain and other

foot injuries. (A pronated foot needs more arch support for

stability.)

Another typical gait problem is supination, or under-pronation.

Someone with supination has an insufficient inward roll of the foot

and stress can be transferred to the knee or Achilles tendon.

Plantar fasciitis can also result from supination. Runners with high

arches and tight Achilles tendons tend to have supination. (The

supinated foot usually needs a shoe with more cushion.)

But gait analysis can also show if one leg is shorter than the

other, if the runner has a hip sway, excessive upper-body movement

or other abnormal movement. An expert performing gait analysis will

look at the entire body, or what Dugan calls the " biomechanic chain. "

" If you come to see me because your heel hurts, I need to look at

your spine, your knees, your ankles, your toes, " she says.

The key to gait analysis, say experts, is to gain some useful

information that will prevent injury. This can involve a simple

change in footwear, use of orthotics, therapies to strengthen or add

flexibility to muscles and changes to one's mechanics or exercise

patterns.

Malit at the Running Lab says, " My intervention is the shoe. " But if

he spots complex mechanical or structural problems, such as the need

for orthotics, he often refers customers to podiatrists, physical

therapists or other medical experts.

A running coach or expert in biomechanics can perform gait analysis

to recommend specific exercises or make changes in training

regimens, says. She uses biofeedback systems to teach runners

how to change their mechanics.

For example, if a runner is landing too hard (a frequent cause of

stress fractures), she can teach him or her to run more softly by

having the runner perform on a treadmill linked to a device called

an accelerometer. The runner can see the shock wave produced by his

or her stride and can adjust, such as by shortening the stride or

increasing the knee flexion, so that the shock wave is softened.

says many problems can be corrected — and performance

improved — through biofeedback.

Consumers who undergo gait analysis should make sure they receive

sound advice. Most experts suggest that gait analysis for injury

diagnosis and treatment should be performed in a healthcare setting.

Consumers who are getting the service in a store should inquire

about the employee's background and training.

" The value in gait analysis is in the person doing it, not the

equipment, " says. " If you're getting a footwear

recommendation, that's not a big deal. But if it's advice on

mechanics, that's something that requires training. "