Point-Counterpoint: Can Toning Shoes Have A Legitimate Impact?
Achilles tendinitis and retrocalcaneal bursitis. The heel elevator/soft rearfoot wedge also relaxes the tension on the Achilles tendon and reduces inflammation and pain.8,12,13 The rocker sole aids in forefoot roll-off and increases ankle joint dorsiflexion at initial contact and greater plantarflexion at toe-off. The rocker sole causes increased ankle joint range of motion. The sole also places the Achilles on an active stretch during the midstance phase of gait and may serve as a mild stretching force.
Pre-ulcerative keratosis in patients with diabetes. Rocker-sole shoes can reduce pressure under the heel and metatarsal heads by 35 to 65 percent.6,14,15 Patients can use rocker-sole shoes prophylactically to treat patients at risk for rearfoot and central ray ulcerations.6 One can further improve the efficiency of the shoe by the presence of accommodative insoles.14,16
Knee osteoarthritis. Preliminary studies have shown that rocker-sole shoes can reduce knee pain in overweight patients.6 Theories behind this effect include: reduced joint loading and pain by strengthening the small pedal muscles; increased quadriceps activity during mid-to-late stance while walking; reduced peak knee adduction movement; and/or increased knee flexion angles.
What Are The Caveats For Using Rocker-Sole Shoes?
While rocker-sole shoes may have exercise-related and therapeutic indications, their use is not completely without risk. Anecdotal reports have linked the use of rocker-sole shoes with sciatica, hip fractures, ankle fractures and Achilles strains.4,17-18 As a result, I suggest addressing several issues prior to prescribing rocker-soled footwear.
1. The patient should review the DVD or instructional booklet that accompanies the shoes. The stretching program should start prior to the use of these shoes, especially in tight, “out-of-shape” patients at risk for straining their Achilles. An “active stretching program” (i.e., night splints, therapeutic stretching and/or physical therapy) may also be necessary to prevent injury.4
2. One should correct limb length discrepancy to prevent musculoskeletal aches and pains. While most patients with limb length discrepancy are asymptomatic while using conventional shoegear, increased pedal movements secondary to the inherent instability of the rocker may cause unilateral pains in the foot, ankle, leg, knee, thigh, hip and/or back. This is a result of excessive strains on the “longer” lower extremity as it goes through pronation-induced malalignments to get the foot on the “shorter” leg to the ground. One should correct for structural and functional components when using rocker-sole shoes.
3. Patients cannot use rocker-sole shoes with foot orthotics, a fact noted in the instruction materials supplied with the shoes.1,2 The inherent instability of the shoes runs contrary to the concept of the stabilizing effect on the function of the foot imparted by a custom-molded foot orthotic.19 The instability of these shoes may exert high torques on the joints of the foot and ankle, and excessive tension on ligaments and tendons. This may result in overuse injuries. With that said, I do sometimes fit rocker-sole shoes with heel lifts, prefabricated scaphoid pads and metatarsal cookies to provide small, nondescript “generic” corrections on foot function if the patient is still symptomatic despite the use of this footwear.
4. One must evaluate equinus prior to the use of rocker-sole shoes. Equinus is a deformity characterized by a decrease in ankle joint range of motion, usually less than 10 degrees ankle joint dorsiflexion.20 Evaluating the type of equinus (i.e., osseous versus soft tissue) and the means by which the patient compensates for the equinus during gait will improve the efficiency of shoe gear.13 A more flexible foot allows for greater compensatory pedal movements in a rocker-sole shoe while a more rigid foot type will place more torque on the pedal joints due to excessive range of motion on the pedal joints.