Impact Force on a Runner's Heel and Leg While Running

For my project I wanted to test the amount of force that a runner’s heel and leg is exposed to, and if new running shoes really do reduce the force. An accelerometer is a device that detects acceleration in the X,Y and Z axes. Acceleration is measured in G-Forces, one G-Force is equivalent to the acceleration of gravity on earth that all things experience at all times. I am using this accelerometer to test the amount of G-Forces that my heel and leg experience while running, and if there is a difference between newer and older shoes. There are a lot of common misconceptions about needing new running shoes. A lot of people believe that Nike is lying to you when they tell you to get new shoes every 500 kilometres. Running shoe companies, and running based stores, like Poulsbo running (my local running store) for example, will tell you that you will hurt yourself if you do not replace you shoes often. However I am not sure if that is completely true, and therefore I decided I would test it myself. The cause of these running injuries that they tell you will get if you do not have new shoes, are derived from the amount of force that your leg and heel experience. They say new shoes reduce the force better than old shoes, but I am not convinced that that is true. This project will be helpful to a lot of people especially those who are prone to running related injuries, and those who would like to know more about them. My project will determine whether these companies are telling the truth, or if they are just trying to get you to shell out another couple Benjamins.

Supplies

1x Arduino uno

1x Sparkfun adxl377 accelerometer

1x breadBoard

1x many jumper wires

1x button

1x LED

2x 10k resistors

2x 30k resistors

6x wires that are approximately the length of the runner's leg

1x laptop that can run the Arduino IDE

Extra components needed for the secondary build:

1x LCD screen

1x potentiometer

1x many more jumper wires

Step 1: My Initial Build

My initial build was a proof of concept. I wanted to make sure that this project was possible before I started investing time and money into it. I used an accelerometer, Arduino, four jumper wires, and my laptop which was running the code. This proof of concept was very important because I learned some valuable lessons with regards to the code. Most importantly though, I learned that this project was possible.

Step 2: Secondary Build

First and foremost I want to say that this build was not necessary for the final build, and it does require some extra components, so this step is completely optional. I added on a Liquid Crystal Display (LCD) so that it could give me the G force values on a computer without the Arduino IDE. before this build I needed to have the Arduino IDE and the code to be able to receive the output data from the accelerometer. With this new build I can run the Arduino from any power source, it does not even have to be a computer. I also added a potentiometer so that I could adjust the backlight on the LCD. This could prove useful if I were to use it outside and the sun was shining on the screen. We have all been in the situation where you are trying to use your smartphone outside but the light from the sun is making it hard to see the screen. So you try and block the sun with your hand, or you turn your back to the sun to try and block it. Another way to fix this common problem is to turn your screen brightness up, and that is exactly what the potentiometer is there for. I would not be able to see the output data very well, but I could adjust the backlight so that I could see it perfectly. The backlight adjustment could come in handy in other instances as well.

Step 3: Third, and Final Build

For my third and final build I combined all of the best attributes of all of my previous builds into one board. I ended up with a very refined and compact module, and the long wires were able to run down my leg without hindering my form. I added a button so that I could start and stop my data collecting at any given time. This was very crucial to getting good data because I would be able to start collecting as soon as I started running, and as soon as I stopped. Therefore all of the data collected pertained to the actual experiment. I also added an LED so that i knew when the data collection was on, or when it when off. This final build ended up being a great success, and it was exactly what I had hoped for.

Step 4: Trouble Shooting, and Some Problems I Had Along the Way

I have had many problems with project. For one my first accelerometer it was very difficult to get the wiring, coding, design and data to be correct. The design was very difficult because I have a lot of restraints, for example how heavy it is, or how big it is. I need to be able to run, and I want to be able to run the closest to my regular running form for this experiment to be accurate. The coding was also very difficult and required a lot of trouble shooting. I had trouble reading a proper amount of G’s from my accelerometer. The mma8452q (my accelerometer) caps out at eight G’s. Sometimes when I would just barely touch my foot to the floor it would read eight G’s and that is simply incorrect, since it is way too high. After some trouble shooting and re-coding however, I was able to get the scaling correct.

Step 5: My Code

I used one of the examples from the Sparkfun library, and I also added a button, and LED myself. this was pretty simple since there are examples of everything in this project, however you do have to combine more than one together

Step 6: Conclusion, and Data Analysis

I see this project as a big success. I accomplished nearly all, if not all, of my goals. I was able to get a lot of very usable data. I learned a lot about coding, wiring, Arduino’s electronic components, building a compact modular system, G force, and running. Now to either accept or reject my statement from my opening paragraph, and the whole reason why I started this project. I wanted to prove the companies wrong by showing that you do not need to buy new shoes every 500 kilometres. Do new shoes really reduce the amount of G forces that a runner’s heel and leg experiences while running? The answer is yes. I compared the amount of G forces that my heel experienced in a pair of new running shoes, old running shoes, vans, and as a control, me just wearing socks. I found that in my socks i experienced up to eight G’s. This was the same amount of G’s as the vans, which is to be expected. In the old running shoes I experienced up to six G’s. in the new runners, I experienced no more than four G’s. As we can see, the new runners were the best at reducing the impact force, and the vans were the worst (not counting the socks since it was the control variable). I guess with my under twenty dollar setup, I can not disprove what the 2.5 billion dollars that Nike has spent over the last five years on research and development has proven for them. Maybe I will spend thirty next time and we will see what happens then.