I just read the following on another fourm and wondered what y'all though of the post by the expert of the fourm:
Remember a good machine is designed to overcome the flaws in the equivalent free weight exercise.
Time and time again the argument of whether machines or free weights are better for building muscle rears its ugly head. The problem is there?s no reason to argue about them. They both can be used side by side, and to build muscle most effectively, they should be.
Any exercise you do with a free weight only has one line of resistance; straight down. This in itself causes inadequacies because of physics. Let?s take a shoulder press for example. You're moving the resistance upwards, but the lever (The upper arm) is moving upwards and inwards in a circular motion. So when you're in the bottom position (With your upper arm parallel to the floor) the distance between the fulcrum or pivot point (Shoulder joint) and the weight is much larger than when you are in the top position (Weight directly above the shoulder). As a result, the weight you're lifting gets "lighter" as you progress from bottom to top, and when you do reach the top, the weight is all but non-existent as the resistance is now travelling straight down the extended arm.
Most of today?s machines now have what's called Dynamic Variable Resistance, which will adjust the weight as you push up to follow the strength curve much closely. I.e. The resistance it applies at the bottom of the movement is less than the resistance at the top. So in our above example, the shoulder muscles are now under a constant and as near as dammit equal tension from the beginning of the movement, all the way through to the end. It doesn?t matter if your arms are bent to 90 degrees, or if they?re perfectly straight above your head, as long as the weight of the weight stack is not resting on the one below, that weight is providing resistance.
It basically comes down to picking the right tool for the job. If the job in hand is a shoulder press, then the shoulder press machine is designed specifically for that job and nothing else whereas a dumbbell is just a weight. If you needed to drill a hole in a wall, what would do the better job, a power drill or a corkscrew? Both would do the job, but a power drill is designed to drill holes in walls. Its sole design criteria is to put a hole in a wall in the most efficient manner. A corkscrew would also put a hole in a wall, but it wouldn't be anywhere near as effective or efficient.
Both free weights and machines are just tools, nothing more. Someone?s success or failure using each has nothing to do with the tool. If someone?s not getting the results they want from working with free weights or machines, the fault doesn't lie in the tool, the fault lies in the application, i.e. the overall routine and application of that routine.
The main issue people have with Machines is that of ?Stabiliser? muscles. By stabilisers, we?re talking about fixator muscles, as discussed earlier. The argument goes like this:
?By using a machine, the body parts not being worked are stabilized and the body parts that are the focus of the exercise are being guided through the path of movement by the machine.
If you perform a similar exercise with a Free Weight, it?s not only the muscles you?re focusing on doing the work, smaller ?Stabiliser? muscles are working to steady your body/the weight and guide it throughout the movement.?
There are a couple of places where this falls down. The first is the concept of ?Stabiliser? muscles. There's no such thing as a stabiliser muscle, only an agonist performing another job (To stabilise you, as explained in the section ?Agonists, Antagonists, Synergists, and Fixators?) at that point in time. For example: In a standing shoulder press, the lower back muscles work isometrically (Contracting statically) to stop you bending over backwards. However, you can work the lower back directly as an agonist, so you're not gaining anything by working these muscles isometrically in a shoulder press if your routine is designed to not neglect the smaller muscles.
Then you've got to take into account what if you don't want other muscles helping you do a movement? What if the situation means you want to isolate a muscle/muscle group as much as possible? In that respect, the machine has a distinct advantage over the free weight for the above reasons.
Now let?s have a look at machines anatomically. Machines "Force you" through a certain movement. Absolutely, that's what they're designed for! Anatomically, your muscles perform certain actions, and machines are designed to provide that action. If the machine doesn't "Fit" you when you do the movement, then (Cheap machines aside) the machine isn't set up properly, so the fault doesn't lie with the machine, it lies with the person using it, or more likely, the gym instructors for not properly showing them (Or knowing themselves) how to adjust all the seats, pads, and lever arms, etc.
On the other side of the coin, free weights are cheap and versatile. A decent set of free weights, a bench, and a power rack will set you back somewhere around the ?200-300 mark. A decent machine which will work just one part of your body will in most cases set you back a minimum of double that.
So in terms of accessibility and flexibility, free weights will always win, hands down. Of course, this doesn?t matter if you go to a gym that has a full complement of machines, but a gym with a couple of machines and no free weights will always be the most restrictive choice when up against a gym with no machines and only free weights.
So the whole free weights are better than machines, and vice versa argument is basically a specious one. Which one?s better depends on the situation and the application. Both are tools. Nothing more, nothing less.