Every spring, they emerge in droves from their winter hibernation. Their unmistakable sound heralds the arrival: flip, flop, flip, flop, flip, flop.
From the beach to the mall and environs in between, flip-flops are the go-to warm-weather footwear for many a person.
And while these same folks will tell you they wear flip-flops for comfort, research suggests this type of footwear is often a big source of discomfort.
And not just that—it can also cause serious problems.
Studies have shown that flip-flops can alter your gait pattern—essentially the way you walk. This alteration affects not only the biomechanics of the foot and ankle, but the knee, hip and back.
In a normal gait cycle, the action begins with the foot making contact with the ground on the outside edge of the heel.
As the forefoot comes to the ground in the stance phase of the gait cycle, the foot begins to pronate, or flatten, to provide shock absorption. The foot adjusts to the surface on which you’re walking.
The foot then becomes more rigid, serving as a lever for the muscles of the lower leg as they contract. As the foot leaves the ground, it enters the swing phase of the cycle.
If the moment of pronation here is too pronounced or too drawn out, it can affect the entire lower extremity.
Excessive foot pronation increases the stress at the knee and hip joints, which can create problems in the foot, ankle, knee, hip and lower back.
A big problem with most flip-flops is the lack of support they provide at the arch on the innermost part of the sole. This allows excessive pronation, which may contribute to dysfunction and pain in the lower extremity.
Flip-flops also affect more than just the kinetic chain of events.
Research has shown that people will experience more pressure on the bottom of their feet when they wear flip-flops, as compared to those who are barefoot or wearing shoes.
Flip-flops can be insufficient for dissipating ground reaction forces. A greater amount of force travels through the lower extremity of someone wearing flip-flops, placing more stress on the ankle, knee, hip and back.
Flip-flops can also cause a shorter stride length and an inefficient gait, leading to increased stress on the lower extremities.
Much of this arises from the flip-flop wearer’s need to hold the flip-flop on with the toes.
Scrunching the toes to maintain the position of the flip-flop activates muscles toward the back of the leg and the sole of the foot, which moves the toes and foot downward.
When walking, we’re supposed to move the toes and foot upward as the foot clears the ground.
Flip-flops hamper this motion, as well as compromising the normal function of the plantar fascia (a ligament on the bottom of the foot). The normal tightening of the plantar fascia allows for improved function of the foot as a propulsive lever.
The reduced function with flip-flops contributes to more force through the lower extremity and decreased stride lengths during the gait cycle.
But here’s the all-important question: What might all of this lead to?
Well, a variety of discomforts, imbalances and overuse injuries, some of which include plantar fasciitis, stress fractures, arch pain, bunions, shin splints, tendonitis in the tendon connecting your kneecap to your shinbone, knee and hip dysfunction or pain, bursitis of the knee and hip, low back pain and more.
It’s not hard to see how flip-flops can cause some serious problems.
The good news? Summer style and optimal foot comfort are still within reach.
“When looking for a sandal, look for one with a contoured foot bed with arch support, as opposed to flat-soled flip-flops,” said John Harris, DPM, FACFAS, a Spectrum Health Medical Group orthopedic foot and ankle surgeon. “In addition, pick a sandal that does not require you to scrunch your toes to hold them on. Perhaps a sandal with a heel strap.”
If you must wear flip-flops, you should limit use to short distances and a short amount of time.
“Parents, be leery of allowing your kids to use flip-flops as their go-to summer shoe gear,” Dr. Harris said, explaining that many of the summer injuries he sees are attributable to flip-flops.
Also, be sure to replace your footwear frequently—it can help ensure a pain-free summer for your feet, knees, hips, legs and back.