Exercise is an important part of healthy living. Our Exercise Science series explores the science behind exercise, keeping you up to date on the latest findings from the experts.
So perhaps I exaggerated with this title, but “it’s all in your nervous system” wasn’t quite as sexy. The truth is, your nervous system is the driver of your body. Most people forget this and just focus on the muscular system. As a yoga therapist and lifelong runner, I see plenty of people plagued with running injuries. I myself was slotted to undergo the knife twice (and twice declined) to treat my Iliotibial (IT) band syndrome and patellofemoral pain (more on what that means later).
The doctors and physical therapists started listing off all of the traditional musculoskeletal things I needed to address: My foot rolled in when I ran, I needed to strengthen my hips, and my VMO (vastus medialis obliques – part of the thigh muscle group) weakness was to blame. I did “monster walks,” performed reclining leg presses with a ball between my knees and foam rolled until I cried. I ran in shoes with descriptors such as stability and motion control. I did everything and anything I could to “fix” my muscles. If any of this sounds familiar, put down the ice pack, dry your eyes, and read on.
What is it that really drives human movement? The answer is plain and simple – the nervous system. Unfortunately that’s where the “plain and simple” stops. Human locomotion is driven by a combination of sensory input and motor output. Just walking doesn’t take a lot of cognitive processing – good news for the text-walkers I see so frequently.
However, the nervous system is highly adaptable to sensory input. In the case of running, a lot of this input comes from our feet. Barefoot running and running foot strike patterns have been hot topics in exercise science for the past few years and both topics remain somewhat controversial. Running with a fore-foot or mid-foot strike instead of a rear foot or heel strike pattern is thought to result in fewer injuries and improve performance. To be fair, the jury is still out on whether this is true.
A cleverly titled article about this controversy immediately caught my attention: “Barefoot running and hip kinematics: good news for the knee?” This study, published in Medicine & Science in Sports & Exercise, the official journal of the American College of Sports Medicine, was conducted by Colm McCarthy and colleagues at Trinity College in Dublin, Ireland. The researchers sought to investigate whether three key movement patterns traditionally associated with patellofemoral pain and IT band syndrome change with footwear.
Let’s sidetrack for a quick anatomy lesson. The IT band is a large sheet of fascia, or elastic connective tissue found throughout the body, that extends from the side of the hip down to the knee. The patella is the knee-cap bone, which sits in a groove at the base of the thigh bone (or femur). Patellofemoral pain is typically caused by improper tracking of the patella in the groove of the femur. The three patterns associated with these “syndromes” are excessive hip adduction (movement of the hip towards the midline of the body), excessive hip internal rotation (an inward rotation of the femur), and contralateral (opposite side) pelvic drop.
The researchers enrolled 23 healthy recreational female athletes and compared gait kinematics (the geometry of motion) of the subjects while running with and without shoes. The results showed that barefoot running, when compared to running with shoes, improved the three key movement patterns. Indeed – it appears barefoot running is good news for the knee!
In a subsequent publication, the research group examined whether a 12-week intervention of simulated barefoot running (wearing Vibram five finger shoes) would change foot strike patterns. At the end of the intervention, all subjects in the barefoot running group moved from heel striking toward mid and fore-foot landing patterns. So what did we just learn? Barefoot running can alter your hip and knee kinematics as well as change your foot strike pattern towards one that is thought to reduce injury and improve performance.
Let’s get back to the original point – your nervous system is at the helm of your body-ship. Subjects in these studies were not asked to do any specific muscle training and the researchers only altered their footwear condition. So how did physical changes occur and why were they maintained in the 12-week intervention group?
If you change the input, you change the output. By removing the subject’s shoes, the researchers altered the subjects’ sensory input or feedback. By altering the sensory input, the nervous system altered the movement patterns of the rest of the kinetic chain, from the foot up to the hip. The fancy term for this is neuromuscular adaptation.
You can easily experience this on your own right now. Go grab a pair of heavy-duty winter mittens. With your newly covered hands, go the nearest door and try to turn the knob. Now take the gloves off and repeat the action. When you change the sensory feedback, the nervous system must change its strategy for achieving the same desired task. The winter mittens inhibited the natural movement of and sensory input from the hand, just as most traditional stability or motion control shoes do with the foot.
The long-term effect of this barefoot running “intervention” is unknown. Barefoot and minimalistic footwear remains a controversial subject. If you are interested in learning more about barefoot vs. shod running, I’ve linked two review articles below. To be clear, my point was not to promote barefoot running, but rather to illustrate how our neuromechanics can be significantly altered simply by our choice of footwear.
By Robyn Capobianco
Science Buffs 