An Active Voice Sports Medicine Bulletin
By Janet S. Dufek, Ph.D., FACSM and Traci L. Delgado, SPT
American College of Sports Medicine.
Injury prevention in the running community is paramount for sports medicine practitioners. As running fads populate, it is important to understand underlying biomechanical processes in order to provide appropriate intervention and rehabilitation therapies to minimize and recover from injury. One of the techniques utilized in the prevention of running injuries is to modify the gait pattern, with one particular contemporary trend increasing amongst runners, i.e., barefoot (or minimalist footwear) running. There is growing evidence to suggest that barefoot running results in changes in how you run (kinematics) as well as the forces (kinetics) associated with running.
For most individuals, barefoot running changes the foot strike pattern from initial rearfoot contact (RFS) to striking the ground with the mid- or forefoot (FFS). This change typically results in a decrease in the vertical impact force at contact, accompanied by kinematic changes. Considering specifically the low back while running, there is evidence to suggest that during the loading response and stance phase, there are positional changes in the low back and pelvis. This leads to the notion that a change in initial contact, as a result of utilizing a different foot strike pattern, could change the position of the low back during running.
Injuries to structures in the low back, such as joints and articular cartilage, have been linked to the propagation of shock throughout the body. The ability to mitigate (attenuate) shock is dependent on passive structures of the body and active movement, and these factors can be influenced by running speed, stride length, and fatigue. If shock attenuation could change by running a different way, then perhaps injury and pain in the low back could change as well. Thus, in our recently published
study in MSSE, we questioned the relationship between the change in a runner’s foot strike pattern and low back posture, shock attenuation, and perceived comfort during running.
Forty-three participants were given instructions on running RFS and FFS and ran barefoot on a treadmill using each pattern. A comfort questionnaire was completed after each condition. We observed that a change from RFS to FFS decreased the overall range of motion in the lumbar spine but did not make a difference in flexion or extension in which the lumbar spine was positioned. We also found that shock attenuation was greater in RFS and that RFS was perceived a more comfortable running pattern.
Greater overall low back excursion with a RFS pattern may suggest that this pattern creates a greater demand for stability in the lumbar spine and therefore could possibly be detrimental for individuals with decreased stability. A concomitant decrease in impact as observed during FFS could potentially prevent or delay degenerative changes such as weakening of shock absorbing structures of the body, including the intervertebral discs. It could thus be suggested that FFS running could help prevent or delay such degenerative effects. To better understand this potential phenomenon, further research should be directed toward investigating the effects of foot strike pattern (adverse or otherwise) in individuals with low back pain or other chronic lower extremity impairments.
Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.
Dr. Janet Dufek is an associate professor and co-director of the Biomechanics Laboratory at the University of Nevada, Las Vegas. Her primary area of research focuses on lower extremity function and performer variability. As a runner, she is an advocate of “within-activity cross-training”.
Ms. Traci Delgado is nearing completion of her doctoral degree in physical therapy (DPT) at the University of Nevada, Las Vegas. She aspires to build her career in an outpatient setting where orthopedics and athletes are her primary focus.
This commentary presents Dr. Dufek’s and Ms. Delgado’s views on the topic of a research article which they and their colleagues published in the March 2013 issue of Medicine and Science in Sports and Exercise®.