Contrary to the advice of many well-meaning but ignorant trainers and “experts” out there, machine exercises can be used to build muscular strength and size, strength gained from machine exercises will transfer to other activities, and machines will not injure you or harm your joints when used properly. If someone believes otherwise, they do not understand exercise in general, they don’t understand what functional ability is or how exercise improves it, and they don’t know how to properly use machines (or, as is often the case, how to properly exercise at all).
Before addressing specific machine training myths, it is necessary to point out just as there are good and bad exercises, there are good and bad machines. Like a good exercise, a properly designed machine provides resistance to the targeted muscles over a path and range of motion based on muscle and joint function, in a manner which efficiently loads those muscles . Unfortunately, there are many machines which do this very poorly or suffer from other design flaws affecting efficiency or safety. While someone with an understanding of machine design can identify these and either avoid them or work around the problem if necessary, many trainers and “experts” are ignorant of this, and often blame machines in general based on their experiences with specific machines of poor design and/or their own incompetence.
For example, a properly designed leg press machine will not cause your lower back to flex to a harmful degree or injure your knees if you are positioned and performing the exercise correctly. If someone says, “leg presses are dangerous because they put too much stress on your knees and back”, it is because they either don’t know how to use a leg press machine correctly or are wrongly generalizing based on their experience with a few poorly designed machines, or both.
It is also necessary to point out that while properly designed machines provide some advantages over free weight exercises both appear to be equally effective for improving muscular strength and size and overall functional ability when used correctly. There are many myths which exaggerate the advantages of machines over free weights as well.
Myth: Machine exercises are harmful to the joints because they involve repetitive movements along unnatural paths and ranges of motion.
Truth: The path and range of movement of a properly designed machine is based on muscle and joint function and a properly designed machine can be adjusted to allow for correct positioning and alignment providing a safe path and range of motion for the majority of people.
Assuming a machine is properly designed, if you are correctly positioned and/or aligned and performing the exercise correctly you aren’t going to be injured by it. If a machine does not allow you to position and/or align yourself correctly or perform the correct movement for the exercise it is poorly designed and you should not use it. Unfortunately, there are plenty of examples of machines with axes of rotation in positions making proper alignment difficult or impossible for some users (alignment of a joint means both the average axes of the joints over the ROM of the exercise and the planes of movement are aligned – most people only consider the first), which cause some users to move into positions which are potentially harmful to the joints, which violate muscular sufficiency principles, etc.
Assuming a machine is properly designed and used correctly it will not cause a repetitive motion injury either, as long as you are performing a reasonable volume and frequency of exercise. If people are experiencing repetitive motion injuries as a result of their training their form and program are most likely the problem, not the equipment.
Myth: Machine exercises do not improve “functional strength” because they do not resemble common body movements in daily living and athletic activities.
Truth: Regardless of the equipment used or the movement performed, the skill of an exercise is specific and improvements in that skill will not transfer to your skill in performing any other activity no matter how similar they appear. The strength gained from an exercise is general, however, and will transfer to improved performance in any other movement involving the muscles strengthened regardless of whether they resemble the exercise movement.
Whether you train with machines, free weights, body weight, manual resistance, some other tool, or a combination of all of them, the strength gained will transfer to all movements the muscles trained are involved in. You just have to plan your program so you effectively train all of the major muscle groups.
Myth: Free weight exercises are more effective than machine exercises for building muscular strength and size because they involve more muscles as stabilizers.
Truth: When you perform an exercise with a barbell or dumbbells more muscles are involved to assist in balancing the weight, but just because a muscle is involved in an exercise doesn’t mean it is under sufficient load to be effectively stimulated by it, and the additional focus required to balance the weight can detract from your ability to intensely contract the target muscles.
For example, the primary purpose of an overhead pressing exercise whether standing with a barbell or seated on a machine is to work the shoulders, upper traps, and triceps. How well it does this is what matters, not whether or the degree to which it involves other muscles as stabilizers. If you are concerned with the strength of those other muscles (and you should be) your program should include exercises which work them directly and far more effectively.
Also, while properly designed machines do a very good job of providing support to counter reactionary force and help you maintain proper positioning and/or alignment so you can focus on working the target muscles, many still require other muscles to work as stabilizers
Myth: Machines with fused movement arms will create strength imbalances because they allow you to train one side harder than the other.
Truth: It is possible to use a machine with a fused movement arm in an unbalanced manner, but as long as you perform an exercise with the intention of working both sides with equal effort this is not a problem. It is also possible to do a large number of very stupid things with a barbell or dumbbells – and people quite often do – but this is the users’ faults, and not the weights’.
If you are working harder with one side at the start of an exercise it will fatigue more quickly and require the other side to work harder later in the set. As long as you continue the exercise to the point of momentary muscular failure or very close to it the average relative effort over the course of the exercise will be roughly equal for both sides. This is not the case with unilateral movement arms where bilateral imbalances are more likely to cause problems.
Machines with fused movement arms provide several advantages over machines with independent movement arms and free weights. It is easier to assist or spot someone using a machine with a fused movement arm, and you can do it in a balanced way from either side of the machine. The ability to use a fused movement arm in a bilaterally unbalanced manner is an advantage when you want to use one limb to spot or assist the other for rehab purposes, or to perform negative-accentuated repetitions. Machines with fused movement arms also require less motor control, allowing you to focus more on the intensity of muscular contraction
Myth: Machines exercises are safer than free weight exercises because they prevent you from moving incorrectly or dropping a weight on yourself.
Truth: No machine can prevent you from positioning and/or aligning yourself and/or using it incorrectly, and it is possible to drop a weight or movement arm in a way that could strike or pin and injure you on some machines. Also, barbell exercises can be performed inside a rack with safety bars or catches set at an appropriate height to prevent you from dropping the weight on yourself or becoming trapped under it.
There are some really badly designed machines and even entire equipment lines I would strongly discourage people from using due to potentially dangerous features, such as motorized machines which abruptly increase resistance when the user begins negative movement (or even more dangerously, in a seemingly random and arbitrary fashion as was the case with several X-Force machines we tested), but often the risk of injury has far more to do with how the machine is used.
A barbell is very safe when used correctly, and can be very dangerous when it is not. A properly designed machine is also very safe when used correctly, and can be very dangerous when it is not. The real problem is neither free weights or machines, it is that many people don’t know how to exercise correctly using any kind of equipment.
Myth: Machines are fine for beginners but advanced trainees should use free weights.
Truth: Most machine exercises require less motor control and are easier to learn than free weight exercises, making them well suited to new trainees. However, there are no advantages of barbell exercises for advanced trainees in terms of improvements in general health, fitness, or appearance. Both free weights and machines appear to be equally effective for these, and with proper instruction either or both can be used safely and effectively by people of any experience level.
Myth: Machine exercises are more effective than free weights because they vary the resistance to match the muscles strength as it changes over the range of motion, while free weight exercises do not.
Truth: Some machines vary the resistance correctly, many do not, and some free weight exercises can be done in a way that matches the resistance curve to the strength curve pretty well. This may not matter though, because most research shows no significant difference in muscular strength and size increases between training with free weights and machines, or between machines with variable resistance and constant resistance.
In theory, balanced variable resistance should make exercise more effective because maintains relatively consistent tension on the muscles over the full range of the exercise, eliminating sticking points and points where the muscles are under-loaded. Some claim this fatigues the muscles more efficiently and increases muscular strength over the full range of motion rather than just the positions where the target muscles are meaningfully loaded.
However, considering machines and free weights appear to be equally effective, it is more likely that as long as the exercises are performed with reasonably good form and a high level of effort the efficiency of fatigue either balances out or is not as important as some believe. Also, strength gains do not appear to be specific to the range of motion trained, so balanced variable resistance may not be necessary for full range strength increases except maybe for exercises where the relative contributions of different muscles involved changes significantly over the range of motion.
Ultimately, how you use it is more important than what equipment you use. When used properly both machines and free weights appear to be equally effective for improving muscular strength and size and all other general factors of functional ability.
Carpinelli RN, Otto RM, Winett RA. A Critical Analysis of the ACSM Position Stand on Resistance Training: Insufficient Evidence to Support Recommended Training Protocols. Journal of Exercise Physiology Online 2004;7(3):1-60
Fisher J, Steele J, Bruce-Low S, Smith D. Evidence Based Resistance Training Recommendations. Medicine Sportiva Med Sport 01/2011; 15:147-162.