How to Build Muscle: A Game of Angles

STACK Expert Kyle Newell breaks down building muscle into motor units and advises how using angles in the gym can recruit more of them and grow your muscles.

Incline Bench Press

I love the show Game of Thrones, so I thought it fitting when my coach, John Meadows, sent me a program with a subsection called "Game of Angles." His concept of how to build muscle also fit nicely into a college course I am teaching.

Building muscle is high on any athlete's list, but most people are unaware of how motor units and angles play into it.

Motor Units

A motor unit is a central nervous system neuron that stimulates the muscles and all the muscle fibers connected to it. Innervation training teaches a muscle to develop more nerve endings so it can be more stimulated and build more muscle fibers. Low-threshold motor units generate low-powered movements; high-threshold motor units generate more powerful movements.

I like to think of motor units as a light dimmer. We recruit just the lower ones (dim lights) and push the dimmer up (or in this case, the intensity up) until the lights are full-on bright, representing the high-threshold motor units, or HTMUs. Once activated, a motor unit stays activated for a period of time (Brown, 2007). If you train at a faster pace during sets and rest for shorter periods between sets, you activate more motor units and stimulate more muscle fibers. If you wait too long between sets or reps, you only recruit the same motor units, which slows your overall muscle growth.

Exercises done with 50 percent repetition maximum (RM) weight at low velocities recruit the lower threshold motor units. If you rest too long at this low level of intensity and let the low threshold motor units deactivate, you won't make much progress.

If you want to really turn on your HTMUs, you need to perform those 1-3 RM sets with exercises such as the Bench Press, Squat and Deadlift, to name just a few. You can also stimulate the HTMUs with dynamic effort sets using 50 percent of 1RM done explosively, or with Olympic lifts.


The angles you use in your exercises directly affects which motor units you activate. The order of recruited motor units is fixed for any given angle (Brown, 2007); but if you change your grip or the angle you use to produce force, you recruit a different collection of motor units.

You could change your grip-width on the Bench Press, change the angle of the bench or even use a different attachment on a pull-down machine (supinated, neutral, pronated, etc.)

Visualize this example: Hold a cup of water above a sand hill and pour the water onto the hill. The water will cut grooves in the sand. If you keep pouring water from the same angle, you will only make those grooves deeper. The same thing happens when you exercise at the same angle. If you change the angle, you create new "grooves" (innervation training paths) and will build new muscle.

Another thing you can take from the sand hill example goes back to the concept of higher and lower threshold motor units. If you continue to pour water out faster and at higher volume, you will make the grooves bigger and deeper—these are your higher threshold motor units. If you pour a little, stop, pour a little, stop and don't pour out sufficient volume, you won't make much of a dent in those grooves and you'll limit how much muscle you can build.

If you understand the game of angles and motor unit recruitment, you will know how to build new muscle. These are simple, yet underused, concepts.

Work hard, work furious and change the angles.


Brown, Lee. Strength Training. Champaign, Ill., NSCA, 2007

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