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Solo Episode Episode 28

Identify & Fix Muscle Imbalances & Injury Risks

  1. [MUSIC PLAYING]

  2. Dr. Andy Galpin

    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 by only increasing your ankle range of motion by a single degree.

  3. 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.

  4. Imagine how much you could improve if we got 2 or 3 or even 4 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.

  5. 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 human was the perfect thing to be. If you looked at an athlete, you would pick the one who was the most symmetrical to be the most successful in all sports.

  6. 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.

  7. Today, we're going to 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 left-handed. That exists in every human. Well, at least about 98% of us. That other 2% can use both sides pretty equally.

  8. 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.

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In this episode, I tackle muscle asymmetries and imbalances — when the differences between your two sides help you, when they hurt you, and what to actually do about them.

I move past the popular "10% rule" and walk through my three I's framework: how to investigate asymmetries across morphology (muscle size and shape), quality (fat infiltration inside the muscle), and functionality (strength, power, and movement); how to interpret the data using context rather than blanket numbers; and how to intervene with a practical five-step correction program built around unilateral training and plyometrics. I cover testing tools from tape measures to MRI, the research on grip-strength asymmetry and aging, and why lower-body asymmetries warrant more attention than upper-body ones. This is for athletes, coaches, and anyone who moves and wants to reduce injury risk or perform at their best.

Show notes

Scientific Articles

Books

Tools & Technologies

People Mentioned

  • David Epstein: science journalist and author who writes on athletic performance and talent development
  • Jill Miller: fascia, mobility, and self-care fitness expert; founder of Tune Up Fitness
  • Mike Boyle: strength and conditioning coach known for functional training and the bilateral force deficit
  • Doug Larson: strength coach and Barbell Shrugged co-host
  • Dr. Greg Rose: co-founder of the Titleist Performance Institute and movement-screening expert
  • Eric Cressey: strength coach specializing in athletic performance and arm care; co-creator of “Assess and Correct”
  • Mike Robertson: strength coach and co-creator of “Assess and Correct”
  • Dr. Charlie Weingroff: physical therapist and strength coach focused on movement and rehab
  • Dr. Kelly Starrett: physical therapist and mobility specialist; co-founder of The Ready State
  • Aaron Alexander: movement coach and creator of the Align Method
  • Dr. Ryan McGrath: researcher at North Dakota State University who runs The Hand Lab studying grip-strength asymmetry
  • Bill Bowerman: legendary track coach and Nike co-founder
  • Leonardo da Vinci: Renaissance artist whose Vitruvian Man represents idealized body symmetry

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