Hi everyone. On behalf of all of us here at Washington University in St. Louis and Boise State University, welcome to national biomechanics day. Today we’re going to talk a little bit about running biomechanics but first why are they so important?
I’m Christina Geisler. I am a cross-country and track runner at Boise State and i’m also studying kinesiology with an emphasis in biomechanics. Biomechanics can lend to discovering why different running gates are the best. Like you’ll hear, oh their running stride is perfect and um usually those provide the most efficiency which is going to help you be able to run faster and stay in the race a lot longer.
Hi my name is Greg Holtzman and I am a professor here at Washington University Physical Therapy and I am the director of the running clinic we have as a part of our clinical practice. Running is often related to injury and it’s really important to watch and understand the way a person runs so you can understand what the potential cause of injury could be. When running or walking the foot is a really important bodily structure that can be used to help absorb those forces. I’ll often ask the runner, do they run on a road type of surface that’s relatively flat or are they running on a surface such as a trail and a park that could have some variation in its terrain such as rocks or roots or dirt or gravel. Sometimes that distinction can be very important because the loads on the lower extremity or on the body can be different in those scenarios.
In order to find out how terrain affects the forces going through the foot we asked a runner to put an insole into her shoes while running on two different surfaces, concrete and grass. The insole measures how the runner’s center of pressure or where the runner’s body weight is positioned on her foot. It also measures the force going through the runner’s foot. Here you can see a diagram of the runner’s feet the green lines show the path of her center of pressure while she was running. We can also see the peak or maximum force. When running on concrete the runner had a peak force of 1260 newtons on her left foot and 1248 newtons on her right foot. Our runner is now running on grass and here is the insole data. The runner had a peak force of 1432 newtons on the left and and 1418 newtons on the right.
We can also look at this data graphically. This graph has time and seconds on the x-axis and force in newtons on the y-axis. This trace is the force measured by the left insole during her run. Each of the peaks is when her foot is on the ground and the valleys are when her leg is swinging through to take the next step. When we add in data from the right insole in orange you can see how the peaks alternate as she stands on one foot and then the other. If we draw a line at the very peak force observed during this trial we can see that it corresponds to a force value of 1260 newtons. If we add in a graph from the trial where the runner was running on grass we can see a higher peak force value of just over 1400 newtons. Because this runner experienced higher peak forces when running on grass it may be beneficial to start returning to running after injury for example by training on a flat surface like concrete and then progressing to uneven surfaces like grass in order to gradually progress the forces seen by the foot and leg as it recovers.
My favorite thing about biomechanics is that it’s more hands-on and it’s fun.
The great things about biomechanics is being able to have the technology to quantify numbers.
Another great thing about biomechanics is it’s so diverse you can study animals, or running, or babies. Anything that floats your boat.