Also referred to as “Rocker bottom shoes” or “Toner shoes”
MBT shoes like the vibram fingers are intended to simulate barefoot training. The focus of the MBT shoes is balance and proprioception. The idea is that these shoes strengthen the small stabilizer muscles of the abdominals, hips, and lower extremities.13 It can be argued that the MBT shoes reduce the force transmitted to the knees by the rocking motion which causes rotational momentum. In this sense they reduce impact and may be effective in the prevention of knee OA.14 For those already suffering from this condition however these shoes may not be an option. For the older patient with poor balance these shoes can predispose him or her to falls; caution should be used before prescribing them.
Barefoot training has become increasingly popular since Vibram released their product “fivefingers” which are essentially protective gloves for the feet. Proponents of this type of training argue that it is man’s natural state to walk/run barefoot as in pre-historic times. From a medical standpoint there are some benefits to this type of training. While shod runners usually heel strike transferring the energy up the kinetic chain; unshod runners generally forefoot or mid-foot strike decreasing the shock and transferring this energy into rotational momentum. Heel striking creates a large impact transient of 1.5 to 3 times the body weight and although shoes decrease this force, they do not eliminate it. Forefoot striking on the other hand produces a much smaller impact transient. Forefoot running may therefore reduce stress related injuries such as patellofemoral pain. (11)
Other benefits to barefoot running include: increased proprioception around the foot and ankle, strengthened intrinsic muscles of the feet, increased bone density of the foot and ankle, and more efficient running (5% less energy is expended.) This type of training is usually not recommended for those with pes cavus feet because they generally have more rigid arch and require the support of a shoe. (12)
Also before training barefoot the area should be examined for sharp objects which may penetrate the foot, or a product like “fivefingers” should be worn. www.vibramfivefingers.com
In a study by Kerrigan,et al, of 68 runners were analyzed in both shod and barefoot conditions. Ground reaction forces and external joint torques at the hip, knee, and ankle were measured. The results of the study demonstrated an increase in peak torque at all three joints while wearing a typical neutral running shoe as compared with those measured while barefoot. A 38% increase in knee varus torque was demonstrated in the shod group, which may increase compression on the medial compartment of the knee and predisposes to wear. The authors also found a 36% increase in knee flexion torque, which may predispose the athlete to patellofemoral pain. Most pronounced was an increase in hip internal rotation torque of 54%. The authors attribute the increases in joint torques to the elevated heel and the medial (arch) support of the running shoe.
Running shoes are designed to decrease impact forces through the foot and leg however this occurs only at heel strike. Peak ground reaction forces and joint torques occur during mid-stance and shoe designs do not address this. (13) Increased joint torques, over time, may predisposes the athlete to cartilage injury.