by Rebecca Lingerfelt, DPT
The latest shoe technology has introduced unstable shoes like Reebok EasyTones and Skechers Shape-Ups. The theory of the unstable shoe is that walking on uneven surfaces improves posture and muscle strength by requiring muscles to be active more frequently. It is important to note that the majority of these shoes are designed for walking; however, newer models have appeared for running.
The Masai Barefoot Technology (MBT) shoe was the first of the unstable shoe models, and the majority of research examines these. In a study of healthy individuals it was found that the shoes promoted increased propulsion to make it easier to move forward; fewer forces that may cause osteoarthritis, stress fracture, shin splints, plantar fasciitis, Achilles tendon pain, and low back pain; increased recruitment of large lower extremity muscles to improve tone; and a decreased recruitment of back postural muscles. Hypothetically, this means that wearing these shoes lead to less overuse injuries and better toned legs.
Results can differ when the shoes are studied with injured populations. A study published this year found no significant difference between wearing unstable shoes and a good walking shoe in patients with knee osteoarthritis for pain with walking or stairs. It has been recommended that the shoes “should be used cautiously” by people with knee problems due to increased joint loading (more force through a joint due to increased muscle activity). In contrast, this same co-contraction (using opposing muscles simultaneously to prevent back-and-forth motion) can improve ankle stability for people with ankle problems. In yet another study published this year, people with ankle instability had improved ankle strength and muscle coordination after completing physical therapy and wearing the MBT shoes.Overall, these shoes are recommended for people with back pain or ankle instability. The shoes are not recommended for people with knee problems due to the increased force put upon the joint and the tendency to over-pronate while wearing them, further altering knee joint mechanics. The important message is to try these shoes, but if you start to have joint pain and not just muscle fatigue/soreness, consider a more stable shoe in the future.
While these shoes may help improve muscle tone, they do not promote weight loss without doing adequate aerobic activity. The shoes also had a minimal effect for experienced exercisers because their muscles are already accustomed to a more demanding strengthening routine than the challenge these shoes provide. The bottom line is that unstable shoes may help a person tone their legs, increase ankle strength/stability, or improve balance if the person already spends a large amount of time standing and does not currently have knee problems. For more information, please see Masai Barefoot Technology: http://us.mbt.com, Skechers Shape-Up Shoes: www.skechers.com/shoes-and-clothing/styles/fitness, or Reebok EasyTone: www.reebok.com/microsites/easytone_reebok.
Dr. Lingerfelt is a Physical Therapist at Boston Sports Medicine