They gave Marilyn Monroe her trademark wiggle. They made the opening scene in Saturday Night Fever. And they are essential to Kerry Washington’s bad-ass Olivia Pope strut. In this third part of our series on balance, we find out if our favorite shoes have us moving in the right direction.
You might remember Newton’s Third Law from high school science class: every action force has an equal and opposite reaction force. When we walk, gravity helps our feet push into the ground. At the same time, the ground reaction force pushes up into our feet. Amazingly, the human body takes advantage of this law—our feet absorb this reaction force and use it to help us walk. We literally absorb energy from the ground!
This happens because our feet are the most moveable part of our body. The joints and tissues are able to change position and function. One of the main examples is the transverse tarsal joint: it lets our feet roll inward as we walk, capturing that ground reaction energy. As our heels lift back up, the joint shifts position to become a stable lever that propels us forward.
Have you ever noticed how walking along a sandy beach is more difficult than strolling through a grassy park? The sandy surface doesn’t provide as much ground reaction force. Our feet adapt to the shifting sand to keep us balanced, and our muscles must generate more of the force that propels us forward.
SHOES GET IN THE WAY
Wearing shoes also changes the way our feet interact with the ground. The effects on walking and balance are exaggerated when the shoes are 4-inch stilettos, but any pair with a stiff sole and elevated heel can be problematic—cowboy boots, loafers, even winter boots.
Remember that transverse tarsal joint? Rigid shoes prevent its natural movement. We compensate for this by unconsciously changing how we move. For example, we try to achieve the inward rolling motion by turning out our feet as we walk (scientists call this external rotation). Take a look at the heel of your favorite pair of party shoes—chances are, the heel is noticeably more worn on its outside edge.
When our foot can’t roll inward, it won’t absorb energy from the ground reaction force. So we compensate by moving our hips more (à la Ms. Monroe). This fatigues our muscles, puts stress on our knees and low back, and compromises our balance. Eventually, it puts us at risk of overuse injuries and falls (particularly in older adults).
So, is it time to ditch the dancing shoes? Not entirely. Think of them like chocolate cake or fettuccine Alfredo: okay in moderation, as part of a balanced (pun intended!) lifestyle.
BALANCE IT OUT
Balance exercises done in bare feet (or minimal shoes) help restore normal joint motion in the lower body. This is a critical step before other physical activity, as the problems linked to stiff shoes can be made worse by an after-work run. The balance workout from part 2 in this series is a great antidote to dress-shoe dysfunction.
Image courtesy of Augustus Binu/ www.dreamsparrow.net/ facebook (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons