Want to get a grip? Then grab a pair of the most popular kind of minimalist shoes, flip-flops, and put them on your feet. Now walk, and feel the flexors of your ankles and toes grip, literally. Meet your flexor digitorum longus. Entombed deep to the gastrocnemius and soleus in the lower leg, the flexor digitorum longus flexes the second through fifth toes, inverts the foot, and aids in plantar flexion of the ankle.
Originating in the middle of the posterior surface of the tibia and traveling down the leg inserting in the distal phalanges of the second through fifth toes, the flexor digitorum longus (FDL) is one of three ankle and toes flexors. Along with the tibialis posterior and the flexor halluces longus (FHL), the other foot flexors, this narrow muscle is a primary player in tiptoeing, navigating rocky trails and picking up small objects off the floor with the toes.
When wearing loose fitting flip type shoes that do not connect to your foot, the FDL has to work extra hard, along with the FHL, to hold the shoe in place so you don’t flop, I mean fall. The gripping of the FDL can result in a change in normal dorsiflexion during the swing phase of the gait cycle. The over-emphasized flexing action on the bottom of the foot can have detrimental effects on the gait cycle of the sandal wearer. It can lead to pain in the heel, in the metatarsophalangeal and interphalangeal joints, in the plantar fascia, and may also cause discomfort up the anterior and lateral side of the lower leg, reaching all the way up through the IT band. Mainly, as we are focusing on the flexor digitorum longus, this slim muscle has to do a heck of a lot of overtime when the action of toe flexion is called upon so intensely.
Though the warmer months are rapidly approaching, switch out the flip-flops for footwear that connects to your feet and save your flexor digitorum longus for hiking in the woods, walking barefoot in the rain, and for some of your favorite standing balanced yoga poses like Half Moon and Tree Pose. Get a real grip and ditch the flips!