By: Barbell Logic Team
Choosing Assistance Exercises: Rate-Limiting Factor
“Imagine an assembly line that manufactures a commodity such as an automobile. Although there are many steps in the manufacturing process, assume that one step—installing the engine—is the slowest. If we want to increase production, it will do us little good to increase the speed of the other steps, such as assembling the chassis. Rather, we should focus our attention on speeding up the processes of installing the engine. We might hire extra people to do the task, or use more machinery, or remove some impediment to the process so that workers can perform more rapidly.” Brooks, Fahey, Baldwin, “Exercise Physiology: Human Bioenergetics and Its Applications,” (4th ed 2005)
In physiological systems, the “Rate-Limiting Factor” is a concept that scientists use to understand complex processes. “First, scientists seek to define the metabolic or signaling pathway by identifying the components and sequences, then efforts focus on identifying the controlling factors.” (Id.) Though strength programming choices (like “which accessory lift should I choose?”) are not nearly so complex, the rate-limiting factor is a useful concept that can help narrow the plethora of possible assistance exercises down to those that are useful for you right now.
Timing is important; you should never add extra assistance work without a good programming rationale. But, at some point, you will need to add or change assistance lifts, particularly after you become more removed from the halcyon days of the Novice LP, where every lift and every day leads to PRs.
Simple training is best when it comes to getting stronger. We use the most basic movements to both drive and measure strength. Our constant goal is to make your squat, bench press, overhead press, and deadlift go up. You do this just by training those lifts and adding weight. Simple. But this does not work forever. At some point, in order to manage your training stress, you need to add complexity. There is a whole rationale for doing so that you can read, listen, or learn about below:
But within the manipulation of training stress, you have a lot of choices for assistance lifts. These should be viewed with respect to their benefit to the main lift that they are assisting.
Imagine each main lift as a process: positioning, sequential motor activation patterns, and body control, each depending on your anthropometry, your built-in neuromuscular efficiency, coordination, and learning processes. There are several factors that affect your ability to complete the lift and several links in your kinetic chain that may be your rate-limiting factor. Like the lazy engine installers in the quote above, you may have a weakness that limits your progress when everything else is running smoothly.
Consider how assistance lifts differ from the main lifts.
| Squat | Press | Deadlift | Bench Press |
| Tempo Squat | Pin Press | Deficit Deadlift | Floor Press |
| Paused Squat | Seated Press | Rack Pull | Board Press |
| Pin Squat | Press Starts | Stiff Legged Deadlift | Slingshot™ Bench Press |
| Box Squat | Paused Press | Halting Deadlift | Bench Press with Chains |
| Squat with Chains | Romanian Deadlift |
They usually change one small part of the lift, increasing or decreasing the range of motion, changing the movement pattern slightly, adding resistance. We call them assistance lifts because they assist the main lift. Their whole purpose is to help your main lift improve. The problem is that there are dozens of assistance lifts, and you don’t want to just throw one into your program, willy-nilly.
How do you know what assistance lift is right for you, right now? Discussing the Floor Press, Matt Reynolds explains this really well. The floor press is useful because it trains a range of motion that is a weakness for most lifters. “The reason we like this lift is because it works the weak point. . . . It makes me stop right where my leverages become more difficult on a regular bench press.” Its usefulness is evident in the training of it. “As you overcome the strength deficit of that spot, you get to the point where you can actually floor press slightly more than you can bench press for your max effort weight. At that point, you know that it’s no longer a weakness.” This is the rate-limiting factor in practice.
As a scientist of your own training, you should pay attention to what parts of your main lifts may be limiting your overall execution. If you are weak off the floor in your deadlift, then maybe a deficit deadlift should be your priority assistance lift. For the overhead press, some people will benefit from training a pin press at forehead height, but others need to put the pins at the level of their chin. Chains take out the momentum you might build during the concentric portion of the lift. Each assistance lift targets a different aspect of the main lift, giving you the opportunity to train it in a different way. A good signal that you’ve chosen a useful accessory lift is that it doesn’t change the loads you are handling too drastically.
Training weakness, or rate-limiting factors in your lifts, is only part of the equation. There are other reasons to choose assistance lifts, like managing or increasing overall training stress. While the rate-limiting factor is not the be all and end all of assistance exercise selection it can help you make well-reasoned decisions in your training.
What are your weaknesses? And what useful ways have you found to train them?
