Identify & Fix Muscle Imbalances & Injury Risks
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What is the main topic discussed in this episode?
the science and practice of enhancing human performance for sport, play, and life. Welcome to Perform. I'm Dr. Andy Galpin. I'm a professor and scientist and the executive director of the Human Performance Center at Parker University. I want you to imagine for a second that I could increase your best race time ever by seven or eight seconds.
What are the three types of asymmetry (morphology, quality, functionality)?
By only increasing your ankle range of motion, by a single degree. You don't have to actually run that exercise because that's been done scientifically and it turns out to be true. To put this in context a little bit, that seven seconds might be what it takes for you to finally cross below that 24 minute mark if you're an elite male running your best 8K time. Or maybe you're a woman and you're trying to finally get below 20 minutes in that 6K. But remember, that's only for a single degree change. Imagine how much you could improve if we got two or three or even four degrees difference in that ankle range of motion. See, this is not just about ankle range of motion. In this particular case, what we're talking about is reducing the asymmetry or the difference in range of motion between the two legs.
Most of you have seen this classic Vitruvian man, right? Leonardo da Vinci's perfect symmetry between the human body. And it's romantic for us to think about that. And in fact, in the early 1900s, we thought that the symmetrical puma was the perfect thing to be. If you looked at an athlete, you would... pick the one who's the most symmetrical to be the most successful in all sports. But that turned out to not be true. In fact, the wonderful writer, David Epstein, if you've ever read his tremendous book, The Sports Gene, outlined and talked about how the body type explosion happened recently after that, where we started to realize some sports and activities require asymmetry, and in fact, are given a huge advantage
when limbs aren't the same length and when the body doesn't work exactly the same way on all sides. Today, we're gonna dive into this because there's also the reality that shows people that have asymmetries, particularly in their lower body, increase their injury risk by as much as 35%. So which is it? Do asymmetries help us? Or do they hurt us? We all have them. The most common one is what we call handedness. You're right-handed or you're left-handed. That exists in every human. Well, at least about 98% of us. That other 2% can use both sides pretty equally. For over 5,000 years, we've been acknowledging the fact that we at least have some different skill on one side of our hand versus the other side.
And the general rule of thumb you're going to hear is 10%. Now, I want you to remember this number because we're going to come back to this over and over and over again today. The difference between one side of your body, front and back, top to bottom, left to right, As long as it's within about 10%, then you're fine. But we actually know scientifically that's not the case. And in fact, if you look at the research on this, one recent review came out that looked at over 6,000 athletes and found that across 30 studies, about a third of the research found that asymmetries led to more injury. About a third of the studies found it wasn't relevant. And then about a third of the studies said, we actually don't know.
Could be somewhere in between. People are really confused right now. We see these other studies. One of my favorite ones in this entire field looked at almost 300 Jamaican kids. Jamaica, of course, being arguably the most dominant sprinting country in the world, despite being really small. And it found that symmetry, specifically just the size of things like the wrist, the size of their ankle and their knees, predicted not only who was faster in the 100-meter dash, but who was also faster 14 years later. And so we have this confusion. What's going on? Should I be symmetrical? Should I not? If so, how much is too small? How much is too big? And what in the world is going on with symmetry and imbalances? And so we're really left with two confusing points.
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Chapters
8 chapters
1
What is the main topic discussed in this episode?
0:00–0:22
2
What are the three types of asymmetry (morphology, quality, functionality)?
0:22–5:44
3
How does laterality (skill vs force dominance) explain common sport asymmetries?
5:44–9:18
4
Why do muscle asymmetries develop (directional, anti-, fluctuating, sporting)?
9:18–12:56
5
What is the bilateral force deficit and when does it matter?
12:56–16:38
6
How should you investigate asymmetries: from tape measures to MRI and ultrasound?
16:38–31:59
7
When do asymmetries (size, quality, function) actually increase injury risk or reduce performance?
31:59–57:20
8
What are the evidence-based thresholds (green/yellow/red) for action on asymmetries?
57:20–1:39:24
Speakers
1 identifiedMore from Perform with Dr. Andy Galpin
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The Fundamentals of Nutrition, Hydration & Performance Fueling
The Fundamentals of Training for Muscle, Strength & Longevity
What Drives Muscle Growth & What Doesn't | Dr. Mike Roberts
Female Training, Hormones & Nutrition: Fact vs. Fiction | Dr. Lauren Colenso-Semple
How to Think Clearly in an Age of Distraction | Sam Harris