On last week’s post, I discussed five variations of a single-leg mini-squat to improve quadriceps strength.
This week I’ll be discussing a recently published article, from the Journal of Orthopedic and Sport Physical Therapy, regarding sound intensity feedback and its role in altering loading impact forces. You can read the abstract below.
Type of Study
Controlled laboratory study with a within-session design. This means that baseline measurements were taken, a type of intervention was performed on all subjects, and the same baseline characteristics were re-examined.
The authors also described this as a proof-of-concept study in which a topic would be explored but further research would be required.
14 college-aged recreational runners.
What Did They Look At?
Three different variables were analyzed before and after gait retraining. They were vertical impact peak (VIP), vertical average loading rate (VALR), and vertical instantaneous loading rate (VILR).
For the purposes of this blog post, I’ll discuss vertical impact peak and vertical average loading rate.
Vertical impact peak (VIP) is the initial force from striking the ground before full bodyweight is accepted during midstance
Vertical average loading rate (VALR) is how quickly this force from the ground is accepted.
Here is an example below (Image credit). The first little bump (labeled VIP) would be considered the vertical impact peak. And the graph could be used to determine the loading rate.
We would generally like these two parameters to be decreased so that we have less initial impact forces and they can be attenuated over a longer period of time.
How was the Study Conducted?
The participants underwent four steps.
1st– each runner established a self-selected running pace during a 5 minute treadmill warm-up\
2nd– each runner ran on a 10m runway, with a force plate that would collect loading impact forces, at this self-selected running pace
3rd– 15 minutes of gait retraining was performed
This gait retraining consisted of 15 minutes of running, at their self-selected running speed, while receiving continuous visual feedback regarding the sound intensity of their foot strikes.
The visual feedback was provided on an iPad, using an app called SPLnFFT Noise Meter, and provided a real-time graphical representation of the intensity of each foot-strike.
During these 15 minutes, each runner was instructed to decrease the level of sound intensity by attempting to run as quiet as possible.
4th– Each runner was re-tested on the same 10 meter runway described in step 2. They were encouraged to use the running strategy used during the gait training period.
Each variable, vertical impact peak and vertical average loading rate, was calculated at baseline and after gait training. A statistical test, called a dependent t-test, was performed to determine if the differences between these variables, before and after gait training, was statistically significant.
And they were.
11 out of the 14 individuals (79% of participants) reduced their vertical impact peak and average vertical loading rate between 28-36%. The changes among the remaining 3 individuals did not reach statistical significance.
By providing the runners in this study with real-time visual feedback, and instructing them to run as quiet as possible, most participants were able to modify their gait in a way which would minimize impact forces at the same running speed.
The authors of this paper report that the impact force decreases in this study were similar to studies in which cadence was increased. But that this method allowed the runners freedom to modify their gait in a way which best suites them. And this freedom appeared to work for 79% of the participants.
I thought this study was very interesting and builds upon several research articles I’ve read regarding increasing cadence to reduce impact forces.
The results from this study lead me to believe that many runners would benefit from simple cuing to run quieter while others may respond more favorably to increasing cadence using a metronome which would provide less freedom but more structure.
I also thought it was great that the application used in this study, called SPLnFFT, is affordable and readily available to the general public. I downloaded it after the reading the study. You can see a few images of it below. There are a lot of different features that I’m not going to get into but it is definitely easy to use.
Questions for Readers
What are some methods you utilize to decrease the impact forces while running?