By Abdurahmaan Saloojee
Abdurahmaan is a Pre-Script coach from Ottawa who loves reading, traveling, and training.
Do you feel like your workouts have been missing something? Does something about their structure feel off? One of the key concepts to understand about exercise selection is internal versus external stability. It is extremely important to differentiate between the two because without it, your workouts within a day will lack structure and intent.
Stability can be described as our muscles’ capacity to resist force. That stability is internal (i.e. created by the body). Stability requirements can change based on the exercise: for example, the stability your body needs to perform a dumbbell lateral raise for medial delts compared to the stability required for a max low bar squat is vastly different. That is internal stability. External stability is exactly as it sounds: external constraints to an exercise that remove the need for us to stabilize to the same degree. A bench, handles, a fixed bar path, can all contribute to external stability.
The muscles that are called on to stabilize, however, are not contracted voluntarily. You may be driving with your legs when you squat (extending your hips and knees), but you are not thinking about contracting your gluteus medius, gluteus minimus, adductors, external obliques, internal obliques, and others. The point is those muscles all contract, but not consciously, which is why exercises where a large degree of internal stability is required tend to be more tiring. Think of a machine row vs a bent-over barbell row: when you finish a set of machine rows, ideally you will feel a burning sensation in the muscles you intended to work. However, when you complete a set of bent-over barbell rows, there is a good chance that in addition to the muscles you were targeting, your core or lower back may feel taxed.
It is important to understand that one way of training is not superior to the other, they are simply different and have separate applications. All you need are filters or lenses with which to look through in order to understand where and when to use a certain kind of exercise. Exercises with a high internal stability requirement (most barbell exercises, for example) have a “glass ceiling” in terms of effort: it takes practice and pristine technique to build internal stability. For most people, their technique will fail before the muscle they are trying to work gets exhausted. Technique and stability thus becomes the rate limiter and will signal the end of a set before the intended muscle is taxed. Exercises that are externally stabilized allow for more output and “work” for a certain muscle.
How can this improve your training?
If you have a combination of externally and internally stabilized exercises in your program, looking to finish the internally stabilized exercises first when you are fresh can improve your overall output on your other exercises. That way, when you are tired, you can shift to more externally stabilized exercises and think less about stability while focusing more on challenging the muscle. If you tax your muscles with too much machine work early, it can impair your performance on your free weight lifts if you do them later in the workout. This can potentially leave you susceptible to injury because you will not be able to stabilize appropriately.
That means that if your goal is hypertrophy, machines will be superior to free weights in many cases because the requirement for internal stability is decreased, therefore you can work the specific muscle more. This is especially true for newer lifters who generally lack the technique and internal stability necessary to push output or hypertrophy on barbell or compound exercises. Newer trainees or people whose primary goal is hypertrophy can largely benefit from a higher selection of machines, cables and more externally stabilized implements to help them reach their goals faster. On the other hand, if a client’s goal is specific to the barbell and free weights (powerlifting, Olympic lifting, etc.), then their training should remain specific.
Understanding this concept of stability allows us to select exercises more intelligently for clients and understand how to more effectively elicit hypertrophy. It is incorrect to demonize certain exercises or types of exercises: everything works to a certain degree. You just need to know when and how to use them, as well as how to optimize exercise selection and order wherever possible.