As a personal trainer, one of the difficulties I often run into is trying to balance what a client can do with what they want to do.  Often times these situations will look like this:

Client: “I want to build my glutes.”

Me: “Okay, let’s add in some lunges today.”

Client: (During the first set) “Ouch, this is bothering my knee.”

I call this dilemma the physiological/mechanical tradeoff.  It’s a tradeoff because, as personal trainers, we know how we want to challenge our clients’ physiology, but we need to be able to do so within the mechanical parameters that are presented.

The Physiological and Mechanical Tradeoff

When we think of exercise, we often think of the physiological component of it — building muscle, dropping fat, increasing cardiovascular endurance, etc.  The mechanical component does get considered, but usually as “form” or as “exercise rules” — “That’s great form on the bench press.  You are keeping your shoulder blades retracted.” “Don’t let your knee go past your toes with that split squat.  It will hurt the cartilage.”

The problems with thinking about mechanics this way are 1) it is nonsense and inaccurate and borderline dangerous to your client, and 2) it is in no way enhancing your value or the client’s experience (see point #1).  As personal trainers, we have a usable working knowledge of how to challenge and change physiology, but we often struggle with the mechanic’s piece.  A simple test:  describe the difference between a moment arm and a lever arm and apply each to an exercise of your choosing to identify the torque and joint forces created by the resistance.  If this is a struggle, there is some work to be done with your understanding and application of mechanics.

Why is this important?  Mechanics should be the #1 thing you are basing all of your exercise decisions on for your clients.  Only after you identify mechanical limitations and considerations with each client should you worry about how to challenge the physiology.  Think of mechanics like the cup and the physiology like the contents.  You can only put as much content in the cup as there is a volume in the cup.  Any more and the cup overflows.  Likewise, you can only challenge the physiology to the point that the mechanics can tolerate.  Otherwise, you get the “ouch, this hurts my knee,” situation.

There are a number of assessments you can do to get an overview of your clients’ mechanics.  Personally, I use the Muscle Activation Techniques™ assessment process with all of my clients.  This gives me insight on how well each of their joints can move as well as how well their muscles can contract.  This is important information to have before I load them with a dumbbell or on a machine.  Having this information not only decreases the risk of the “ouch, this hurts my knee,” situation, it also allows me to create a truly personal exercise session with each of my clients based around what their body is presenting.  The result is that my clients are able to progress faster with fewer issues because the exercises are created for their needs instead of trying to fit them to an exercise.

Some actionable steps for you would be to:

1) Start assessing the mechanics of all of your clients before and after each session.  How did they come in today vs. how have they come in in the past?  How did their mechanics change from start to finish?

2) Start improving your working knowledge of mechanics and how it relates to exercise.  Practice identifying the axis, line of force, lever arm, and moment arm for each of the exercises that you have a client do.  These will be difficult to see at first, but it will get much easier with practice.

3) Start identifying the joint forces that are created with each of the exercises you have a client do.  Just like seeing the axis, etc., this will be challenging at first but will get easier.

4) Start basing your exercise decisions first within the mechanical context of what the client can do, and then the second figure out how to appropriately challenge their physiology within that context.

Some great weekend courses to look into if you are interested in learning more about this are the Resistance Training Specialist™ (RTS™) courses as well as the Muscle Activation Techniques™ (MAT™) Jumpstart courses.  Both of these series will radically transform how you work with your clients from an assessment and training perspective.  And, as a special bonus for reading, if you sign up for any of the MAT™ courses, you can get a discount on the price by using the code “MAS” when you register online.

Was this Article Helpful?

If this article was helpful to you, please consider linking this article to your own blog or sharing this through the social buttons below. You will also find other great articles at “Expert Advice“.

Charlie Cates

Charlie Cates

Charlie Cates is a mastery level Muscle Activation Techniques™ Specialist (MATm), a mastery level Resistance Training Specialist™ with honors (RTSmh), and a Certified Personal Trainer through the National Academy of Sports Medicine. He is a certified MATRx™ foot and hand practitioner and is a candidate to graduate from the MATRx™ total body program in February 2017.

Charlie attained a Bachelor of Arts degree from Williams College in 2010, where he played varsity basketball for four years. In 2016 he graduated from Northeastern Illinois University with a Master of Science degree in exercise science.

A type-1 diabetic, he is the owner of Muscle Activation Schaumburg in Schaumburg, IL . He is an instructor for the Muscle Activation Techniques™ program, introducing students of all different backgrounds to the MAT™ process.

Charlie specializes in managing and improving the function of his clients’ muscular system through the MAT™ process and utilizing RTS™ principles.

He can be reached via e-mail at Follow him on twitter at @CharlieCates!
Charlie Cates


News collects all the stories you want to read