can you guys answer a question that is probably pretty basic?
So, when I was in high school, they took us to the weight room in the gym and ran us through how to use the machines. The gym teacher went on and on about how free weights were obsolete, machines are much better because you can isolate muscles (maybe? this was over 10 years ago), etc. Now it seems that everyone is back on (or was always on?) free weights. Why is that?
My theory, based on occasionally looking at this thread, is that machines are safer for inexperienced people, but doing "free weights" adds the dimension of form, which is interesting/makes you aware in a different way/makes it more fun?
The answer is surprisingly complex and nuanced and I'll try not to geek out too hard over it.
Muscles are machines that produce force. They comprise many fibers, all of which produce force. Your nervous system fires off these fibers, thus causing force to be produced.
But there's a huge difference between a slow force exerted over time (pulling a plow) versus a fast force exerted over time (shotputting something). Therein lies the distinction between strength and power. Most sports value power over strength.
The longer a muscle remains under tension, the more likely it is to grow new fibers. In this sense, machines and isolation are great because you can just hammer away at a muscle until it gets so tired it starts signaling the endocrine system "We're out of juice, boss, please send more proteins so we can start building more fibers." This is the equivalent of the military saying "Attrition rates are terrible, we need more recruits."
Getting the nervous system to fire the fibers more efficiently is a trickier matter. You can throw more recruits at an army, but without a well-oiled command and control mechanism, it's going to be a useless army. (As a real world example: the Iraqi military was the fourth largest in the world and folded like a house of cards when the Americans came in during Desert Storm.) Training the nervous system is a matter of coordinating many muscles at once, usually in a compound movement and very often in an explosive "power" movement. Free weights are superior because you have to engage a boatload of muscles to keep things stable. There are concepts like "muscle irradiation" where tensing a muscle will allow adjacent muscles to contract more easily, etc.
Since sports generally value the ability for efficient force production over size of muscles, free weights have historically been the mainstays of training. Even here, barbells are a compromise. Ideally, kettlebells are the best because the center of gravity changes as you lift it, thus making it something you constantly have to adjust muscle fiber firing to handle; dumbbells are also good because they have fuller ranges of motion and engage each side of the body separately. But it's hard to progress on these things because you'd need many of them in an increasing weight pattern, and it's hard to load things like a squat with dumbbells or kettlebells. Barbells are the compromise, that allow you to progressively overload your muscles and also let you do things like squats and overhead presses beyond what you can clean up to your shoulders.
The big problem with free weights is that bad form is very dangerous. Since most people don't go to the gym to train for a sport, most people just want to look good without needing a coach or risking bad form. Here, machines are a good option as they allow the ability to swole up your muscles without risk of hurting yourself. The fact that your muscles will be swole but your motor patterns won't be coordinated is a moot point since you probably won't be sprinting or tackling or scoring a GOOOOOOOOOOOOOOAAAAAAAAAAAAAAL anytime soon. For the general gym, then, the machine is a great way to offer a "fitness" service without liability. I think the opinionated curmudgeon Mark Rippetoe says it best in the intro to
Starting Strength:
Among the first tools developed to practice resistance exercise was the barbell, a long metal shaft with some type of weight on each end. The earliest barbells used globes or spheres for weight, which could be adjusted for balance and load by filling them with sand or shot. David Willoughby's superb book, The Super Athletes (A.S. Barnes and Co., 1970) details the history of weightlifting and the equipment that made it possible.
But in a development unforeseen by Mr. Willoughby, things changed rapidly in the mid-1970s. A gentleman named Arthur Jones invented a type of exercise equipment that revolutionized resistance exercise. Unfortunately, not all revolutions are universally productive. Nautilus utilized the "principle of variable resistance", which claimed to take advantage of the fact that different parts of the range of motion of each limb were stronger than others. A machine was designed for each limb or body part, and a cam was incorporated into the chain attached to the weight stack that varied the resistance against the joint during the movement. The machines were designed to be used in a specific order, one after another without a pause between sets, since different bodyparts were being worked consecutively. And the central idea (from a commercial standpoint) was that if enough machines — each working a separate bodypart - were added together in a circuit, the entire body was being trained. The machines were exceptionally well made and
handsome, and soon most gyms had the obligatory, very expensive, 12-station Nautilus circuit.
Exercise machines were nothing new. Most high schools had a Universal Gladiator multistation unit, and leg extensions and lat pulldowns were familiar to everybody that trained with weights. The difference was the marketing behind the new equipment. Nautilus touted the total body effect of the complete circuit, something that had never before been emphasized. We were treated to a series of before-and-after ads featuring one Casey Viator, an individual who had apparently gained a considerable amount of weight using only Nautilus equipment. Missing from the ads was the information that Mr. Viator was regaining size he previously had acquired through more conventional methods as an experienced bodybuilder. Jones even went so far as to claim that strength could be gained on Nautilus and transferred to complicated movement patterns like the Olympic lifts without having to do the lifts with heavy weights, a thing which flies in the face of exercise theory and practical experience. But the momentum had been established and Nautilus became a huge commercial success. Equipment like it remains the modern standard in commercial exercise facilities all over the world.
The primary reason for this was that Nautilus equipment allowed the health club (at the time known as the "health spa") industry to offer to the general public a thing which had been previously unavailable. Prior to the invention of Nautilus, if a member wanted to train hard, in a more elaborate way than Universal equipment permitted, he had to learn how to use barbells. Someone had to teach him this. Moreover, someone had to teach the heath spa staff how to teach how to teach him this. Such professional education was, and still is, time consuming and not widely available.
But with Nautilus equipment, a minimum-wage employee could be taught very quickly how to use the whole circuit, ostensibly providing a total-body workout with little invested in employee education. Furthermore, the entire circuit could be performed in about 30 minutes, thus decreasing member time on the exercise floor, increasing traffic capacity in the club, and maximizing sales exposure to more traffic. Nautilus equipment quite literally made the existence of the modern health club possible.
The problem, of course, is that machine-based training did not work as it was advertised. It was almost impossible to gain muscular bodyweight doing a circuit. People who were trying to do so would train faithfully for months without gaining any significant muscular weight at all. When they went to barbell training, a miraculous thing would happen: they would immediately gain — within a week — more weight than they had gained in the entire time they had fought with the 12- station circuit.