EMG (electromyography) is the measurement of the electrical input to “activate” a muscle, and is often used as an indication of how much force the muscle will produce. It can be a useful research tool, and one that I’m very familiar with, having spent my two years of grad school working in the Exercise Neuroscience Lab at UMass Amherst. That said, the results from EMG-based studies, especially surface EMG, are frequently misquoted, misinterpreted and poorly applied.

Today’s Thursday Throwback discusses some of the limitations to EMG, and what you should be on the look out for as someone that is likely to read someone else’s interpretation of these studies. As I always say, if you want better answers, you have to ask better questions. Today’s post (and the linked article) will help you do just that.

Were You Duped by EMG?

Last week I got an email from my friend Rob McLean with the Colorado Avalanche in reference to an exercise that is considered the “best” because it produces higher EMG levels than other exercises. Rob’s question was, simply, “what do you think?”

A couple years ago, I wrote an article for StrengthCoach.com that Coach Boyle was gracious enough to allow me to re-post at my site here: EMG for Strength Coaches

This article identifies and explains a lot of the common myths associated with interpreting EMG-driven research and is a great starting place for people new to EMG altogether. There are additional considerations when interpreting EMG research that I think are relevant to those in training and sports medicine professions and to the general “fitness enthusiast”, as it will allow you to better spot bullshit (and bullshit interpretations) when you see them.

False Assumptions

1) Force Production = Force Expression
People tend to equate EMG activity with instantaneous force production. Because of the time course associated with the electrical input signal stimulating a mechanical action, this is an inherently misguided notion. That said, even with this assumption, force production does not always equate to force expression.

Force production is the mechanical tension developed in the muscle. Force expression is how that force translates into movement or the control of movement. The two differentiate primarily based on activity of synergistic and antagonist muscle groups and structures. As an oversimplification, envision the biceps brachii producing 5 units of force and the triceps brachii producing 0. You can imagine that the elbow would flex at an appropriate speed based on the force production of the biceps. Now envision an identical situation, but with the triceps producing 4 units of force. The elbow would still flex, but now it wouldn’t be 5 units of expressed elbow flexion force, it would be 1. This example removes all syngerists and the concept of connective tissue tensegrity and mechanical force dispersion, but provides a simple illustration of the difference between force production and force expression.

Isolation without integration is never the goal of a hockey training program

Often times it’s force EXPRESSION that we’re most concerned with, not force production. The major take home here is that EMG studies that focus on the comparison of activity within a single muscle and compare this amongst different exercises completely overlook the importance and inevitably of antagonist and synergist activity.

2) More is Better
The underlying assumption and arguably largest misinterpretation of EMG is that MORE activity is a GOOD thing. In reality, EMG activity always needs a contextual qualifier to rationalize whether increased activity is beneficial or detrimental. My friend Jim Snider from U of Wisconsin did a great job of explaining this in his presentation over the weekend at BSMPG’s Hockey Symposium. Not every muscle plays the same role within the body. There are segmental stabilizers that create a stable base from which more global mobilizers can function. More EMG activity in these stabilizers, especially at the expense of coordinated firing patterns relevant to their true function in movement, is likely detrimental to performance.

This is about as functional for hockey as smoking cigarettes

Secondly, it is often the case that the goal of any given muscle is to use the absolute bare minimum of activity necessary to accomplish a given task. This is true in the interest of energy preservation. This is one of the reasons why we don’t coach a “hard brace” during plank exercises. In this situation, we’d be encouraging a high threshold strategy for a relatively basic task. Instead, we aim to optimize body position and ensure proper breathing patterns and simply allow the nervous system to appropriately interpret the force needs to provide accordingly. Utilizing high threshold strategies for low threshold tasks has a number of other deleterious implications, but that of excessive energy use is not to be overlooked.

Wrap-Up
I fully understand why some interpret EMG studies the way they do, but isolating an individual muscle in EMG is no better than attempting to isolate individual muscles in training. There are likely more implications for this research in a rehabilitation setting than in a training setting, but in both environments it’s important not to overlook the vast mechanical and neurological integration of human movement. Getting back to Rob’s question, my rationale for including some exercises and excluding others goes well beyond isolated gross neural input signals. Every exercise we use serves a specific purpose and fits within a linear and/or parallel progression. In other words, my interpretation of an exercise’s proficiency is based on my particular training philosophy and system, which is likely quite different from most others. As always, it’s important to critically analyze information as it becomes available and not get caught up in something just being “new”. Remember, hyped up garbage is still garbage!

To your success,

Kevin Neeld

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A couple days ago, I posted an article comparing a few lower body power tests, and how they may or may not be “hockey specific”. If you missed that article, you can check it out here: A Hockey-Specific Power Test

A comment that I’ve gotten a few times, and something I had considered myself while interpreting the data, was simply that the lateral bound test would be confounded (or at least influenced) by the height of the individual. In other words, because it involves jumping off of one leg and landing on the other, having longer legs and therefore a larger lateral excursion would lead to increased jumping distances. I think it would be hard to argue that leg length doesn’t in some way influence a test like this, but it’s important to remember, as I noted in the previous post, that the ability for longer legs to equate to larger lateral excursions depends on a number of factors, notably pelvis structure and positioning, femoral head architecture and positioning, and length of the adductor complex on both sides. Bottom line is that when sifting through the data, many of the top achievers were among the smaller kids on the team and many of the bottom achievers were among the taller kids on the team. In short, there’s a lot more to the story than just how tall someone is!

Last Friday I had an opportunity to sit down over a cup of coffee and catch up with Joe Heiler from Sports Rehab Expert. I’ve known Joe for over 4 years now and I was fortunate to have a chance to contribute some articles to his site early in its evolution. Now, SportsRehabExpert.com is over 4 years old and has really grown into an incredible resource.

Sports Rehab Expert

With the recent release of my Optimizing Movement DVDs, Joe wanted to talk about some of the topics discussed in my presentations, including:

  1. An overview of the presentation: Who it’s for, what’s covered, and what people can expect from it
  2. The 4-step process to establish Optimal Movement in athletes and non-athletes alike
  3. Why the appearance of full mobility could actually be a bad thing
  4. The assessment process we use with our athletes and clients, and what I would use in a time crunch
  5. Some of my more “surprising” assessment findings
  6. The 4 “Pervasive Movement Considerations” that influence the correct performance of almost every exercise
  7. How we’ve used kinesiotaping techniques to restore mobility and reduce asymmetries
  8. How all of this integrates into our training system

Joe was kind enough to let me repost the interview here so you can listen to it for free. You can download it at the link below:

Click here to listen >> SportsRehabExpert.com Interview on Optimizing Movement

Optimizing Movement DVD Package

Optimizing Movement continues to get great reviews from those at both ends of the rehabilitation to elite performance continuum. This is what Penn State University Hockey Strength and Conditioning Coach Rob McLean had to say:

“In Optimizing Movement Kevin does an amazing job of laying out many of the dominant philosophies that are influencing our industry, and discusses how they influence his approach to training.  Much of the FMS, SFMA and PRI information is very complicated and yet Kevin presents them with a simplicity that allows you to grasp the concepts quickly and recognize how important it is to look for movement dysfunction. He then discusses how he evaluates his athletes and uses that information to direct his movement-based approach to create a training program that deals specifically with the athletes’ limitations. Lastly Kevin reveals overwhelming evidence to show that most athletes walking through our doors already are dealing with sub-threshold injuries that must be managed or else we, as strength coaches, will only make them worse and never achieve the best result possible for our athletes.

I try to review all the great information that is available every year from Cressey, Robertson, Reinold, Weingroff, Ward, Jamieson and many others. For me, Kevin’s Optimizing Movement was definitely the best DVD I’ve seen this year and I would consider it one of the best DVDs I’ve ever watched. This is the DVD that brought everything together for me and allowed me to implement my knowledge and define my core beliefs. I strongly recommend it to strength coaches or athletes who are looking for direction in applying these philosophies to create athletes that are more durable and move better.”

Rob McLean, Head Strength and Conditioning Coach, Penn State University Hockey

Check out OptimizingMovement.com for more information!

Next week I’ll be posting a couple articles discussing early in-season training programs for hockey players, so be sure to check back. In the meantime, enjoy the interview and don’t forget to stop by SportsRehabExpert.com to check out all of the articles, videos, interviews, and forum discussions!

To your success,

Kevin Neeld
OptimizingMovement.com
UltimateHockeyTraining.com

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