6 (good) reasons to use machines for strength development

In the training world, machines are up to debate. Sometimes considered to be reserved for novices or for people returning to training after a long inactivity period, they couldn’t stimulate the « stabilizing » muscles in the same way as free weights (barbell, dumbbell, kettlebell…), they would allow less freedom of movement than those kind of weight, they could be less « functional », less « specific », and would be of use only to learn the basics of a movement or to target specific muscles.

But if we take a closer look at some of these arguments, we realize that they may be questionable, depending on the context and the objectives sought.

The goal of this article is to present my point of view on the subject, focusing primarily on lower body strength development through a comparison between the Back Squat and other exercises (Hack Squat, Trap Bar DL-Squat*, Smith Machine Squat, Hatfield Squat, Belt Squat, and Leg Press* – presented at the end). Nonetheless, some principles may also apply to upper body strength development.

*I’m well aware that the Trap Bar isn’t technically a machine and that the traditional Leg Press machine, where the hips are flexed, doesn’t really replicate a squat pattern. I’ve chosen to use them as part of a global lower body strengthening exercise and as alternatives to the Back Squat.

Reason n°1: What matters is strength, not an exercise in particular

The omnipresence of the Back Squat in many programs surely stems from the fact that numerous studies (Case & al., 2020) indicate a reduced risk of injury when one is able to lift a given load: we often find a threshold corresponding to 2 times bodyweight in Back Squat as a « target » to be reached.

But here, what’s important is strength capacity, not the ability to load a specific exercise. This capacity can be built through other, potentially easier and faster means. Indeed, according to scientific research (Schwarz & al., 2019), machine squat training can provide at least the same benefits as those obtained when training with a free load.

In addition, over a certain weight on the bar, the Back Squat places a lot of load on the spine, which can become the limiting factor of the exercise. In such circumstances, where the back limits the load that can be used in an exercise targeting the lower body, then this exercise may not be the most suitable for developing lower body strength optimally.

To limit the load placed on the spine, especially with a partial range of motion, you can work unilaterally (i.e. focusing on one leg at a time) rather than bilaterally. However, the lack of stability when you have a barbell on your back limits the load you can use, and therefore the maximum force you can produce. Machines can compensate for this lack of stability, enabling you to work more effectively on one leg.

When performing unilateral exercises on a machine, we can work on joint angles similar to those found in sports with large amounts of force. Some studies (e.g. Speirs & al. in 2016; Zhao & al. in 2023) show that unilateral options are as relevant as a bilateral Back Squat for improving strength, speed and change-of-direction skills.

Reason n°2: A faster learning

To be able to achieve a movement with a relatively high load without additional support, such as in the Back Squat, it requires a special level of skill and mastery to avoid endangering oneself and to get specific adaptations. Acquiring such skills takes time, practice and rigor.

In contrast, machines such as the Hack Squat, Leg Press or even Trap Bar have a much more favorable learning curve: with this kind of tool, the movement is « easier » to perform, you can get comfortable with it quickly, so you can increase the load significantly faster.

This is useful when we’re focusing on maximum effort production, particularly with younger populations, with individuals having less body control than adults, and for whom it’s sometimes harder to express their full strength potential (due to a lack of habit of expressing large amounts of force and growth-related factors, among others).

Machines can thus represent an advantageous option in strength development, for anybody.

Reason n°3: A higher potentiel thanks to the stability

The strength-stability paradigm states that when we improve stability in a movement, we increase the potential for force production. One of the first priorities of training is to stabilize the spine for safety matter. If the brain is unable to activate the muscles of the spine effectively, then the strength, speed and mobility of the rest of the body will be impacted. Those 3 qualities require a stable support to be expressed at their best.

It’s crucial to practice the tasks you want to perform well, so that your brain learns to stabilize your spine as you move, thereby promoting optimal force production. We can hence conceptualize jumping, speed, agility and change-of-direction exercises as dynamic stabilization exercises, which must be trained in practice if we want to get better at them.

When it comes to strength work, machines offer a stability and a sense of security that the Back Squat can’t match, especially in unilateral exercises. The combination of the two facilitates max intent during the movement and very high strength measurements. Furthermore, as you don’t really need to stabilize yourself at the start of the movement, force production can be faster than with a free load.

Even for power work, machines are interesting: according to some study (Helland & al., 2017), performing weightlifting movements with a motorized machine can help produce more force than with a free load, due to better stability. And as a reminder, weightlifting isn’t the only way to develop power.

Reason n°4: Are we really specific with strength work?

Let’s turn now to an argument often put forward against the use of machines: the lack of « specificity« . In my opinion, and as I explained in this article on the link between squatting and vertical jumping, the actions carried out in sport and those carried out in the weight room are too different to really argue that the latter would be « specific » to the former.

From a neurological standpoint, strength has to be taken in the context of a given task, with an intent, contraction speeds and joint angles that are specific to it – and distinct from any other task.

From there, why not use a machine to simplify strength (and power) training? We could work on various strength qualities to develop general abilities, and at the same time practice the athletic tasks we want to progress on so that these general strength abilities can be expressed.

Besides that, stability demands are pretty dissimilar between a squat pattern with a heavy load on the back and sporting efforts such as sprinting, changing direction or jumping with momentum. If you want to optimize dynamic stability in these types of effort, you need to practice them directly.

With strength development, we want to condition the body’s tissues so that they are capable of withstanding large amounts of force, which doesn’t necessarily mean having a barbell on your back. What matters is general capacity, not the aptitude for an exercise. 

And to get back to the idea of specificity: although carrying a heavy load and performing athletic efforts in a sporting context are distinct tasks, some machines can enable strength to be developed in positions closer to those found in sports.

For instance, with a Hack Squat, the torso can be kept more upright, and the foot placement can be adjusted so that the knee is more or less forward when we get low (thus targeting the quadriceps to a greater or lesser extent). In this way, you can reinforce angles and positions more « specific » to jumping with a run-up.

Angle comparison between a 1-leg approach jump, a 2-leg approach jump and a Hack Squat movement

Reason n°5: Better adaptations?

When we find a way to perform a movement more comfortably (e.g. with more stability), we can potentially use a higher load, and therefore produce more force. When we feel less stable on a movement, the overall activation of the body may be higher because the muscles are making more effort to stabilize the body (through co-contractions), not because they are producing more force during the movement.

If the goal is for muscles to be able to produce as much force as possible, then the stability and sense of security aspects inherent to machines could be highly advantageous; neurological and physiological gains could be maximized.

Also, with a free load, acceleration is restricted during the concentric phase of the movement for safety’s sake: we decelerate towards the end in order to remain stable. Adaptations can then be attenuated, even more so when loads are relatively light.

When stability isn’t an issue, deceleration can be significantly reduced, resulting in more ballistic movements, even in unilateral exercises.

This intent for explosiveness is not unique to high loads; it can be found with any type of load when using machines. This offers the possibility of working on several aspects along the strength-velocity continuum and on various strength qualities (presented in a previous article). If we can focus solely on the effort, we optimize power production.

Reason n°6: Some kind of freedom of movement

Paradoxically, machines such as the Hack Squat or the Leg Press in supine allow some freedom of movement that free weights don’t. Indeed, despite the defined trajectory, a squat movement can be performed in a variety of ways, as body and anatomical limitations are less of a factor – whereas squat movement with free weights depends mainly on anatomical structures.

Advantages include :

• Variation in foot position, toe orientation and ankle dorsiflexion,

• The load placed on the knees can be modulated by the placement of the feet on the platform, which determines the degree of involvement of the quads and glutes: if the knee remains above the heel and the tibia stays relatively vertical, then the glutes are used to a greater extent. But, if the knee goes further forward, above the toes, then the quads (and the knee) are put under greater strain,

• The possibility of performing the movement while being on the front of the feet, heels slightly off the ground, enabling greater load on the foot-ankle-leg complex,

• Potentially greater range of motion, with anatomical limits having less influence on the movement (the body’s natural mobility comes less into play). Machines can therefore be used to promote joint health via mobility work,

• A load that can be lower than bodyweight with a Leg Press for instance, which is useful in certain conditions (particularly in rehab or for mobility), 

• It’s easier to work unilaterally (which is very useful when you want to « balance » the strength between each leg).

Because the same movement can be performed in many ways, there’s less risk of monotony and overuse of the same structures in the same way over time. With a barbell on your back, you don’t really have access to all these movement options.

Options

In addition to the Hack Squat, there are plenty of other solutions for strengthening the lower body when you want to focus on the intent without having stability issues:

Trap Bar Squat or Trap Bar Deadlift

Smith Machine Squat

Leg Press

Hatfield Squat

Belt Squat

Conclusion

In the same way as stretching and weightlifting, if you or your athletes enjoy using free loads, there’s absolutely no problem to it. However, if you don’t enjoy those, I hope this article has convinced you to explore other options without worrying about potential poorer results.

The goal of strength and conditioning is always to become better at the sport, not in the weight room. Working with extra weight is only an aid to athletic development, which is why it’s sometimes a good idea to take advantage of simple, effective ways of developing specific qualities – such as max strength work with machines.

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