What scientific evidence says cables build less muscle than free weights?

Question

Look at any classic bodybuilding book or DVD and it will say free weights are superior to cables (and machines) for muscular hypertrophy. Joe Weider and Arnold Schwarzenegger are two famous proponents of this idea. Their claim is that humans have evolved to work against gravity and free weights provide a natural gravitational force, while cables do not. I understand how machines are inferior because they don't work stabilizer muscles, but I don't understand how this logic proves cables are suboptimal.

A) Evolution

Who says humans have evolved to get bigger muscles from working against gravity? If anything, technological advances have made humans work less against gravity over the centuries. We do not toil on the farm like our forefathers. We now have cars, computers, and robots to do heavy lifting for us.

B) Contradiction to overload principle

Isn't the key to hypertrophy to subject the muscles to ever-increasing unusual stress, thereby making them adapt to this new stress? Bodybuilders know that doing the same routine over and over make their muscles become complacent. Since cables provide a force that is unlike the gravity we deal with every waking moment of our lives, then wouldn't cables stress the muscles more than free weights?

Answer 1

I'll try to stay tight to your "science" and "evidence" clauses, because there's a whole lot of non-science reasons to use free weights. (Just off the top of my head, there's cost, versatility, compactness, and portability.)

This roundtable discussion (PDF), with copious references, is one of my favorite sources for the machines/free-weights science. Among the points made therein:

• (Wathen) "There is some evidence that more carryover is likely with free weights than machines when training and testing in both modes." (page 21)
• (Carpinelli) "...there were no significant differences (P < 0.05) between the [free-weights-trained or machine-trained] groups for any of the [strength] variables. It appeared that vertical jumping ability was improved to a greater extent by training with free-weights and the Universal apparatus than by training with the Nautilus device. However, the differences are relatively small, and in view of the similarity of the strength gains, the practical application of the finding is unclear” (ibid).
• (Carpinelli) "The absence of any supporting evidence suggests that when used properly, free weights and machines produce similar results in a healthy, athletic population." (ibid) While that's true, I would argue that the very act of choosing machines produces a radically different and markedly inferior program due to choice of exercises, but I can't prove it.
• (Wathen) "Augustsson et al. (3) indicated that free-weight squat training has more impact on vertical jump performance than does a program of isokinetic knee extension and hip adduction. There are few studies in this area, and most are equivocal, but more evidence points to specificity of muscle action type and movement pattern favoring dynamic freeweight movements that closely approximate the sport movement (5,7, 15). After all, most sports performance is dynamic, multijoint, multiplanar, requires balance, and deals with both eccentric and concentric actions (3, 10). Sounds like free weights." This is a great passage.
• (Stone) The same conclusion, stated more succinctly: "The major contributing factor to the superiority of free weights compared with machines is the ability of free weights to mimic and overload most athletic (and daily task) movements. Because of this aspect, there can be a greater transfer of training effect."

All in all, it is a balanced discussion with tons of studies to curl up and read.

As to your specific questions, I do not see how the fact that most middle-class Westerners sit a lot and are weak has anything to do with how we evolved. I would venture to say that we know with fair certainty that our ancestors mostly got strong by lifting things, carrying things, and running. I fail to see the relevance of this point to whether machines are empirically superior to free weights, except to point you to the inherent joy of training and playing outside. (Erwan le Corre has more to say on this topic.)

To address your point about cables and machines being different enough to produce different stresses: most machines, though less so with cables, dramatically reduce the number of muscles involved in a motion. They are designed to isolate muscles instead of allow the body the act as a whole. So, yes, the leg curl machine might provide a different stressor to more strongly incite growth in the hamstring, but as noted in the references above, that stressor is highly specific and has less carryover to everyday life and sport.

Answer 2

(Your question asks for scientific evidence, so I can dig up references for the points I make, if you would like.)

An example

Consider the back squat. For this exercise to be done properly, you need to be able to stand up from a squatted position with barbell on your posterior deltoids. If this is done with proper form, the barbell will follow a perfectly vertical path that keeps it in place directly above your midfoot.

Here are the things about just this one exercise (deadlifts, too) that I don't think can be replicated in a cable exercise:

• a whole-body hormonal response that can't be triggered by smaller, single joint exercises, or exercises using a smaller number of smaller muscles
• an ability to progressively increase the weight on the bar without limit (what happens when you reach the maximum capacity of your cable machine?)
• gravity always pulls the bar straight downward, to allow you to stand up with proper form (a cable system would have to be pretty complicated to always pull straight down, even in the case where you shifted forward or backward slightly)

The overload principle

Barbells do give an overload that is unlike the gravity you experience in everyday life. You don't ever stand up with 250 lbs on your back in everyday life, but can do this with a barbell, thus providing the unusual stress necessary to stimulate muscle growth. And when your body gets used to 250 (probably after that one workout), do it with 255.

From an expert

From Mark Rippetoe (emphasis mine):

There is simply no other exercise, and certainly no machine, that produces the level of central nervous system activity, improved balance and coordination, skeletal loading and bone density enhancement, muscular stimulation and growth, connective tissue stress and strength, psychological demand and toughness, and overall systemic conditioning than the correctly performed full squat.

Answer 3

I don't think you'll find any. Mike Mentzer has talked about this - free weights, machines, cables; they all have their pros and cons. Quite clearly using all of them appropriately is superior to using only one of them. It's possible (although not likely) that a study might show that exclusively using cables is inferior to exclusively using free weights, but that scenario is pretty contrived anyway, as the only reason you'd exclusively use one or the other is due to the unavailability of any other options, in which case superiority or inferiority is a moot point.

A big problem you'd also run into with any such hypothetical study that may show it is how they're comparing both types of equipment. Are they looking at what cables are superior for, or are they looking at what free weights are superior for? That initial bias in testing methodology would affect the results. There's also a question of how the pulleys affect the weights - while you might be lifting the same weight with a barbell as the selectorised plates, the pulleys might make the load effectively lighter on your muscles therefore putting them under less stress to adapt.

Now if we skip aside from looking for a scientific study, and consider the reasoning - exersices like the back squat and the deadlift engage every muscle in your body, and more muscle engagement promotes more testosterone production which is key for building mass. I see no reason though why a properly designed cable system wouldn't allow for performing a deadlift - the one in my gym doesn't allow for it as my face would run into the equipment to get into a deadlift position, but I can imagine a machine that would allow it. That would be a further confounding variable. Free weights are pretty consistent, one barbell is the same as another barbell, regardless of manufacturer. Weight machines differ from make to make and model to model. That of course makes it much more difficult to find good instruction on machine use compared to free weights.

Answer 4

Here's a good article on Bodybuilding.com - http://www.bodybuilding.com/fun/keats1.htm

I think your question answers itself (which makes it a great question). If you separate the muscle building from other physical improvements (stabilization, ligament strength, physiological), then there probably is little difference and possibly more benefits to using cable/machines. Cable/machines help focus effort on specific muscles and that focus probably helps them build faster....the overall problem is that a big muscle in itself has little benefit (outside of looking good and if the bicep a way to attract women). If you want a healthy, fit body, you need to develop the entire human structure and mental fortitude at the same time - and yes, I think lifting free weights has physiological benefits over cables/machines...muscle strength, stabilization, bone density, muscle-to-bone (tendon), bone-to-bone (ligament) and cardio build together better with unstable, heavy objects - free weights, sand bags, kettle bells, sledge hammers, etc.

Answer 5

Cables are equivalent to free weights in that they require you to use stabilizing muscles. Compund movements such as deadlift and squat have the advantage that they train many muscles at the same time, and they use a movement pattern that is part of our evolution. Squatting is something small children do instinctively. Same goes for picking things up off the ground (deadlift). These movement patterns are shaped by gravity.

Answer 6

I started out using free weights- barbells, dumbbells- and made fairly good gains. However, I injured my shoulder doing upright rows with a barbell and decided to give cables- not machines- cables- a try and ever since my development has increased ten-fold. I get a far, far better workout with cables than I ever did with free weights because there is increasing resistance throughout the entire movement which is not there with free weights.

I have never injured myself with cables and don't expect to. Any way you look at it, bodybuilding- building a bigger, stronger physique is nothing more than pitting muscle against resistance and as I said for me cables provide increasing resistance throughout the entire movement.

Yes, barbells are superior to cables where squats are concerned but I do a lot of hill sprints which build my legs without harming my hip and knee joints as badly as squatting with barbells can. One last point: I don't want to be huge like Arnold or Ronnie. I merely wish to have a muscular, athletic physique and am far more concerned with symmetry than bulk.

I'm old school and think the physiques of Steve Reeves, Bill Pearl, John Grimek, Reg Park, Jack Delinger, etc., are far more pleasing to the eye than today's steroid-ridden "bodybuilders" with their balloon-like "muscles" and distended, bloated stomachs who are only concerned with how big they can get. And, they certainly don't get that big by just eating the right food and lifting weights, do they? I also do tons of chin-ups which I have found is the best back builder or for that matter they best upper-body exercise there is. That's where I'm coming from.

Answer 7

I know one thing. I've built more muscle faster and got better results from free weights and consistency than I got from doing cable exercises for weeks on end. I got elbow problems and injuries from doing tricep free weight and cable exercises like overhead extensions, so now except for push downs I stick with machines. I'm moving almost half the stack or more with good form and hypertrophy rep ranges with challenging weights to failure. I still don't have a horseshoe to show or flex, but all my biceps exercises are all free weights. In the same amount of time I went from flat left arm and a little bump on my right, and now I got a thicker round bicep with a decent peak. It's hard not to draw a conclusion that free weights are superior when it comes to building muscle.

That and I see guys with great physiques and they hit the gym up as much as I do except they been doing it for years, same thing for them hardly anyone does free weight tricep exercises, they use cables and are pushing almost the whole stack. They got defined shoulders, arms, chest, but no tricep horseshoe. Granted I assume none of them are juicing, and I'm not, but I never see these stacked dudes at the gym with big defined horse shoes to flex, and all of them are usually doing mostly cables and machines for their triceps because they don't want to injure themselves.

So. No science involved here. Just what I see and what I've experienced myself. Sometimes you just gotta call it what it is.