Saturday, November 27, 2010

Injury Limits to Fat Loss: The Law of Repetitive Motion

In The Theory of Fat Loss, I discuss in great detail several functional limits that can hinder a fat loss program. The ones that tend to stick out the most in people's minds are postural and injury limits. On this blog, I have already described two common functional limits. In fact, these have been some of my most popular entries. They are anterior pelvic tilt and lower back pain (Part 1 and Part 2).

What I have not yet done (until now that is), is describe at the most elementary level the root cause of almost all postural and injury limits. If you understand how injuries happen, you will be empowered to prevent them.  So, I have decided to give you another exclusive look at an excerpt from my book.

Before I do this, however, I have a favor to ask of you. This blog exists to provide you with information so that you can make a real, lasting change in your life, should you choose to do so. You should notice that this blog isn't loaded with external advertisements. Google adwords has no place here. I don't use sales videos or pop-up ads. The only things I endorse to you on this site are things that I have found personally valuable to me. For the most part, I endorse myself... because without an audience, this blog is worthless.

So, what I am asking you to do is very simple. I have a page for this book on Facebook. If you have found this blog to be helpful to you in any way, please head to that page, and click the "like" button. I know many of my readers have already done this, so what you can do after that is simply invite 3 of your friends to "like" the page as well. There is a link under the picture of the book that says "suggest to friends." Please pick three of your friends who you feel would be interested in what I have to say and attach a little personal message inviting them to to the page. I would be very grateful if you did this for me, and who knows, you might be the person that inspires them to make a difference in their lives. The page can be found at:

Thanks in advance. Without further ado, here is your exclusive excerpt on everything you need to know about injury:

Appendix B

Mechanism of Soft-Tissue Injuries

The Law of Repetitive Motion
I first learned about the law of repetitive motion from two fitness professionals (Mike Robertson and Eric Cressey) and their “Building the Efficient Athlete” DVD set. The law states that

I stands for Injury to tissue
N stands for Number of repetitions
F stands for Force of each repetition as a percentage of maximal strength
A stands for Amplitude (aka range of motion) of each repetition
R stands for Rest (between reps, sets, training days, etc.)

This equation is similar to a mathematical formula but it is not as exact as one. It is more of a guiding equation that models a mechanism of injury. As you can see by the equation, the factors that contribute to injury are increased repetitions and increased % of maximal force output. The factors that reduce injury are increasing the range of motion of each repetition and taking adequate rest time during training and between training sessions. Also, there is a threshold. If you stay under the threshold, you will not get injured, but the further you go over the threshold, the greater the severity of the injury will be.

Basically the equation comes down to this. People get injured if they try to do too much too soon. Maybe they try to lift too heavy without first training to get strong. Maybe they do too many repetitions (runners are the biggest culprits of this). Maybe they push themselves too hard without resting. Maybe their form is terrible, and they did not take the time to learn how to move through a correct or a full range of motion. These all fit into that same category of too much too soon.

A few things still need to be described in a little more detail as they are not immediately obvious upon viewing the equation. Take fatigue for example. Does fatigue fit into this model as an injury factor? Yes. If you think about it carefully, can you think of what causes fatigue? High reps, high percentage of maximal force produced per repetition, and short rest time can contribute to fatigue. All three of those are accounted for in the equation.

What about faulty mechanics? Those definitely contribute to injury, but are they accounted for in the equation. If you think about faulty mechanics as muscular compensations (using the wrong muscles to “cheat” a movement pattern), then everything makes perfect sense. Inability to properly utilize the gluteal muscles is a common problem. If a person with this problem tries to participate in high intensity sporting activities, other muscles will have to produce a lot more force to take up the slack. How many athletes pull their hamstrings, strain their quadriceps, or pull their groins? The part of the equation that is being discussed here is F. When the wrong muscles are recruited, they use a much higher percentage of their maximal force capability as compensation for the under utilization of the prime movers. If F is too high for too long, injury is going to result.

One point the equation does not address is that range of motion has a limit. Obviously there exists a potential to go to far just as there is a potential to not go far enough. A full range of motion for an exercise is good. Going too far will cause muscle tears or other injuries, and not going far enough may lead to muscle imbalances. Furthermore, in some regions of the body like the lumbar spine (low back), for example, range of motion is not typically something you want to train at all.

Finally, how does soft tissue work (massage, trigger point therapy, foam rolling) fit into this equation? The purpose of soft tissue work is to improve muscle tissue quality, release areas of excess muscle tension, and to increase tissue extensibility. In other words, soft tissue work can help improve the force capabilities of muscles, improve the quality of rest time, and help correct muscle imbalances and range of motion limitations.

Practically, what can one do to decrease the risk of injury? The best options include training to increase maximal strength, taking deload weeks (time periods where intense training activities are limited) after every training phase, participating in frequent and supervised training to improve skill and coordination, and getting regular soft tissue work.

Luckily this author's interpretation of the law of repetitive motion and the theory of fat loss send the same message. Prepare. 


Best of luck to you during the Holidays!
-Timothy Ward
Author, The Theory of Fat Loss

PS- If you haven't done so yet, please head to and suggest it to three of your friends. Together we can make a positive change in people's lives!

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