Detrimental Effects of Thong Style Flip-Flops on Kinematics
Why minimalist sandals? To allow for proper foot function!
Let's get one thing straight: Earth Runners are NOT flip flops!
Flip flops affect how you use your feet and require more effort to stay secure, while our minimalist sandals allow the foot to act as if it were barefoot, free of all the kinematic nuisances of flip flops.
Earth Runner sandals require NO awkward gripping action of the toes or midfoot plantar flexion to maintain contact between the thong and the foot!
Earth Runners are commonly confused with flip flops to the uninitiated, but we promise you there is no flip to these flops!
Studies show that flip flops alter the gait pattern, which affects the way you walk and everything upstream, from the biomechanics of the foot and ankle, to the knee, hip and back.
The way you have to grip flip flops also leads to shorter strides and an inefficient gait, which is another contributor to stress on the lower extremities. The first contact in a natural gait cycle, like that attained in minimalist sandal, is the outside edge of the heel contacting the ground. As the rest of the foot nears the ground, it begins to pronate (flatten) to provide shock absorption, making adjustments based on the terrain underfoot.
With flip flops, however, the gait cycle and how you use your feet is altered. The gripping action used to keep the flip flop in contact with the foot leads to excessive pronation, which can increase stress in the knee and hip joints, and create pain and problems throughout the body.
Dr. Justin Scott, an expert in Chiropractic BioPhysics, explains some of the problems associated with flip flops:
Pain, discomfort, and injuries such as: plantar fasciitis, hammertoe, stress fractures, arch pain, bunions, shin splints, tendonitis, knee and hip dysfunction or pain, bursitis of the knee and hip, low back pain, metatarsalgia (an inflammation of the ball of the foot), and more.
Adaptations are made when wearing flip flops to help the foot cling to the sandal:
Increased contact duration when the ankle is in dorsiflexion, with reduced hallux dorsiflexion, to retain the thong during weight acceptance.
Greater midfoot plantar flexion during midstance (single leg stance) → gripping action to retain the thong during stance.
Wearing flip flops requires foot adaptations which, with prolonged wear, may result in muscle overuse syndromes for rearfoot dorsiflexors and midfoot plantar flexors.
Flip-flops only have one (often thin) band connecting the sandal to your foot, which means its your foot's job to keep the flip flop from flopping off! This puts your tendons under constant stress, which can cause painful inflammation called tendonitis.
When we're walking, the toes and foot should move upwards as our foot clears the ground. The scrunching of the toes to keep the flip flops on activates muscles in the sole of the foot which does the opposite of this and moves the foot downwards. This scrunching also affects the plantar fascia ligament, which impairs its ability to help the foot working as a propulsive lever.