Using Physics to Drive Change
For any motion with a given mass, the more momentum that gets to that object, the faster it will go. Full stop.
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Last week I wrote a summary on our first Reboot Insiders seminar, which was an intro to Motion Capture.
To follow that up, I wanted to summarize my takeaways from our most recent talk- Using Physics to Drive Change. Last month, Jimmy was joined by Dr. Travis Ficklin and Dr. Robin Lund to focus on how biomechanics- and specifically the laws of physics- can be used to improve athletic performance.
Biomechanics
The talk started with the group discussing biomechanics, with three definitions:
Travis: “the physics of human movement”
Jimmy: “applying the principles of mechanics (ex. F=MA) to the human body”
Robin: “describing human motion in on objective way”
As a non-scientist, I am going to go ahead an endorse Robin’s viewpoint, as he gets to the point as quick as possible.
I also made my own definition after listening to this discussion: Biomechanics is using movement data to determine 1) the what 2) the why and 3) the what’s next.
While movement data can be analyzed a different ways, we think it is important to get beyond statistical correlations and look at causation.
By having a deep understanding of physics, we move past the what and get to real analysis, recommendations, and most importantly, action.
Momentum
The crux of what we do at Reboot Motion- and what I view as the simplest way to explain our analyses- is analyze the flow of momentum through the body.
Let’s use a pitching motion as an example:
A pitcher starts their motion by pushing on the ground. The ground then pushes back and creates external ground reaction forces.
Although force is created as long as the athlete’s body is in contact with the ground, moving forward the focus is on conserving the momentum created as its moves through the body and eventually into the ball.
In other words, the pitcher’s goal is to optimize the transfer of momentum. Let’s look at why:
Momentum = mass X velocity
This simple formula is the key to 1) why small objects move fast and 2) why efficient movement drives optimal performance.
As the pitcher’s momentum moves from the ground through the body to the ball, the mass of the object (the earth - > the torso -> the arm -> the ball) is dropping at an extraordinary rate, causing velocity to increase.
This is why we can throw a baseball faster than we can throw a football. And why we can do both faster than we run.
It is also why a pitcher can still throw a baseball quite fast without the most efficient form.
However, without maximizing efficiency a pitcher will not be throwing as fast as they otherwise could.
For any motion with a given mass (pitching, hitting, throwing a football, etc.), the more momentum that gets to that object, the faster it will go. Full stop.
Explaining Biomechanics
The deep dive into biomechanics, physics, and the conversation of momentum was great for me. But what followed was even better…because it focused on the key to driving change: communication.
First, listen to Robin’s answer on “Is the hardest part of biomechanics is explaining it to athletes?”, followed by Travis emphasizing the extreme value he places in the coach-athlete relationship:
I love these two responses, as it shows the perfect relationship between biomechanist and coach.
For example, listen to Robin to discuss the motor learning programs he creates. He talks with the team’s athletic trainer and physical therapists, comes up with the one big thing to work on, and goes to work…for a while. His focus on building a roadmap and maintaining consistency are invaluable. We can’t replicate this skill with software.
At Reboot, we think great coaches like Robin are already doing biomechanics innately.
The goal for any biomechanist is to connect the dots, quantify the results, and arm coaches with the best tools to build their already deep toolkit.
Marrying Science and Sports
Motion Capture
The last two topics I want to highlight are audience questions. While these may not necessarily match the “Using Physics to Drive Change” topic, they highlight the thought process behind marrying science and sport.
First, the group tackles a science question about the trade-offs between marker based motion capture and marker-less mocap solutions:
While this answer could get quite technical, it didn’t here. The focus remained on the coach and on the athlete.
Especially at the college level, coaches are aware of the time data collection requires. Robin quickly mentioned any trade off in data quality that exists between the two solutions is irrelevant. The time saved simply matters more.
Jimmy and Travis bring up other advantages for marker-less solutions, including more convenient ways of data collection and providing a true game environment.
No one talked about joint centers or frame rates or machine learning. The focus was on the sport- on the coach and on the athlete.
Elbow Injuries
Finally, the panel was asked about predicting elbow injuries. I love how this time the group took a scientific approach to answering a sports specific question.
While we can greatly understand the factors that increase risk or decrease risk, we are nowhere close to “predicting injuries”.
We may know:
More force = more risk
More muscle strength = less risk
More muscle activation = less risk.
But we have to stop there. Unfortunately, risk is a continuum, while outcomes are binary.
While this response has very specific takeaways for pitching, it is another example of how sports and science are intertwined.
We should always be asking tough questions, evaluating data in an objective way, and searching for the true answer. And we should always do so with clear objectives to help athletes, coaches, and teams.