It Must Be the Shoes

By Duston Morris, Ph.D., ABD, M.S., ACE, USAT

There is longstanding controversy about the advantage and/or disadvantage of running shoes. Should a
runner wear a motion control shoe, a stability shoe, or a neutral shoe? A plethora of shoe choices,
combined with runners and specialty stores uncertain on how shoes relate to ground reaction force and
joint compression force maybe increasing the risk of lower extremity injuries and degenerative joint
disease. In other words, running shoes may be increasing the risk of running injury and osteoarthritis.

Recently, Kerrigan and other researchers1 addressed the effect of running shoes on lower extremity joint
torque during running. They looked at 36 healthy women runners who had no history of degenerative
joint disease and were currently without any kind of musculoskeletal injury. All of the runners were
running a minimum of 15 miles/week. Each runner was prescribed standardized running footwear which
was the Brooks Adrenaline (stability shoe). These shoes would be comparable to other stability shoes
manufactured by other companies (i.e. Nike, Asiac, Sacouny). Ground reaction force and joint torque
was measured for each runner.

Results of the study demonstrated a prominent increase in hip and knee torque. Disproportionate
increases were recognized in the hip internal rotation torque, knee flexion, and knee varus torque.
These increases are likely due to the elevated heel and increased material under the medial aspect of
the foot1. There was a 36% increase in knee flexion torque which most likely increases the workload of
the quadriceps, increases strain in the patella tendon and increases stress in the patellofemoral joint.
There was also a 38% increase in the knee varus torque which usually related to more compression
loading on the medial tibiofemoral compartment, which is a leg site that is prone to degenerative joint
changes. Finally there was a 54% increase in hip internal rotation torque, which may increase the risk of
osteoarthritis at the hip joint.

These findings suggest a number of things. First, running shoes may be contributing to increased stress
and workload at a number of joint sites in the lower extremities. Chronic stress and work load at these
sites may lead to additional injuries and degenerative disease such as osteoarthritis. Second, it may be
important for runners to consider wearing shoes that have less heel cushion and material in the medial
aspects of the shoe. Thus, runners may want to consider low-profile shoes, or a shoe like the Nike Free
that supposedly provides minimal cushion and replicates barefoot running. Third, it is important that
runners learn correct running form and technique and that they work on strengthening muscles that
support the lower extremities and help absorb ground reaction force.

There are many runners who have moved towards barefoot running as a way to minimize these types of
problems. Personally, I am indifferent on whether or not runners should run barefoot. If a runner
chooses to run barefoot, I recommend limited volume and only on very soft surfaces that are free of
debrief, in order to limit ground reaction force and the possibility of foot injuries. Finally, I continue to
support running on soft surfaces for 90% of training and only run on hard surfaces to prepare the body
to race on harder surfaces. I have been consistently running for over 10 years, with many of those years
where I would exceed 40 miles/week. During this time I have had no major lower extremity injuries and
struggled with severe iliotibial band syndrome (ITBS) on one occasion. I attribute this to running on soft
surfaces, selecting the proper type of shoes based on the surfaces I am running on, and flexibility and
strength training to support the lower extremities. Runners should consider these things to decrease
incidence of injury and the likelihood of degenerative joint disease.

1 Kerrigan et al., (2009). The effect of running shoes on lower extremity joint torques. Physical Medicine and Rehabilitation, 1,
1058-1063.