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Free Weights vs. Machines: Research Review

Strength outcomes in fixed versus free-form resistance equipment.

Spennewyn KC, J Strength Cond Res. 2008 Jan;22(1):75-81.


Purpose:
The purpose of this study was to compare measures of strength and balance between subjects using fixed form or free-form resistance training equipment to determine whether there is a difference in strength or balance outcomes.

Methods:
Thirty previously untrained subjects, mean age = 49 (+/-3.7 years), were randomly placed in either a free-form strength group (FF n = 10) utilizing a commercially available free-form plate loaded resistance device, a fixed form strength group (FX n = 10) utilizing a commercially available fixed range selectorized resistance device or a control group (C; n = 10) who did not exercise. All groups were assessed during a pretest (T1) and a posttest (T2). The exercise groups were asked to exercise over a 16-week period, increasing resistance based on a standardized 8-12 repetition protocol. The same muscles were targeted in both exercise groups, all groups were instructed not to change their dietary habits.

Results: A one-way ANOVA was used to detect differences among the groups using baseline and end results data. FX group increased strength 57% from baseline while the FF group increased strength 115% from baseline. A statistically significant difference (P = 0.000001) was detected for strength production in the FF over the FX group and (P = 0.0000144) over the training and control groups. Balance improved 49% in the FX versus 245% in the FF groups. Testing revealed a statistically significant difference (P < or = 0.003). The control (C) group did not show significant improvement in either strength or balance.

Conclusions: Results of this study indicate a greater improvement in FF over FX in strength (58%), and balance (196%). Additionally, the FX reported increased pain levels while the FF group reported lowered overall pain levels.

Thoughts and Ramblings:


I ran across this study in one of the recent Journal of Strength and Conditioning publications and thought that it would be a good one to post up. Obviously, for those that read this blog on a regular basis, you can probably guess that I am more of a free weight guy than a machine based guy. In fact, I currently work in a facility where we don’t have machines. The closest we have is 2 free motion cable towers, a seated row and a seated lat pulldown (both cable based machines). Other than that, we have the standard, benches, barbells, dumbbells, power rack, and bumper plates. So yea, I am not much of a machine guy.

Anyway, this study set out to test a variety of different things. The subjects were sedentary, which the study defined as not having participated in a regular exercise program in 6 months or more. Also, five subjects with in both exercise groups (the free weight and the machine group. I will throw out the control group for my comments, obviously since they did no exercise and made no changes to daily living, they made no improvements) experienced headaches 2-4 times a week (for unknown reasons).

Before I go on, the term in the abstract, Free Form (FF), refers to the subjects in the group who performed their exercises on a free motion type machine. Free Form does not mean free weights (IE barbells and dumbbells), even though I do use the term free weight from here on out. So just keep that in mind.

The group that performed the free weight exercises saw great improvements in strength and balance (however the machine group also increased their balance through the study, although it was not significantly greater than the free-weight group). The frequency of headaches in the two groups also dropped and this reason was unknown (perhaps, exercise is just good for you!).

What they didn’t tell you in the abstract above, which you do learn in the study, is that joint pain was measured on a scale of 0-10. Subjects that were in the free-weight group whom had know pre-existing, but not debilitating, joint pain prior to this study, as determined by a pre-study questionnaire, experienced a 30% DECREASE in joint pain! However, the subjects in the machine group reported having an 111% increase in joint pain, when no one in that group had reported joint pain before the study began!

So what does this all mean? Machines are bad; free weights are good….blah, blah, blah.

The last point about the joint pain I found very interesting. Part of the issue was probably in the fact that these were sedentary people who had not participated in an exercise program in a very long time (and they were all over the age of 30, so not too old, but they weren’t spring chickens). One of the problems with using machines and performing a repetition maximum test (in this case it was 8-12 repetitions to failure) is that you can load up the machine a lot more than you can with free weights (or in this case, the free motion machine) which means you put your joints under a lot more stress and, since you are on a fixed plane of movement, you are able to compensate, or overcompensate, to a greater extent with other muscles that might otherwise not come into play (although when you are working to a maximum, you start to really reach with everything you have). So, the situation of being sedentary and having the ability to load up a machine, which stabilizes the weight for you and allows you to go to town with a maximum effort, is not a god combination from a joint health perspective.

Do I think machines are bad? Not really. Do I think they have their place? Yea, at times I think they are okay. I try and not speak in absolutes and try to be more of a “middle of the road” type of guy when it comes to this stuff. Machines, although they should not make up the bulk of your training, can have their place if you goal is hypertrophy, since they do allow you to load up the weight a little more than you would under a free-weight conditioning, and allow you to be stabilized and just worry about making a strong contraction. Obviously, these conditions don’t lend themselves well to sports performance (or even real life), since our muscles don’t operate in an isolated manner, but rather function in harmony with one another. However, from a bodybuilders perspective, I could see machines having some place. As well, since the weight is stabilized for you, later in the workout, as fatigue sets in, they may be a safer option, especially if you are dieting for a contest and you need to maintain a certain level of intensity (defined as the load being lifted in relation to your 1 repetition maximum) which would be otherwise difficult with a free weight type exercise (IE a leg press vs. a squat), since there is some strength loss as you cut calories, diet down and lose body weight.

What I will say is that if you do use a machine in your training from time to time, make sure you use proper technique. Since the load is stabilized for you, it is very easy to let your ego get in the way. Just this night at the gym I saw some guy doing a hammer strength chest press. He had it loaded up way past his limit and every rep he would arch his back like crazy, his elbows would flare out to the sides and his shoulders would shrug like mad. Obviously none of this is healthy by any means. What made it even better was that he was only doing about 3 reps per set. Why the hell would you bother with a 3 rep max on a machine exercise? That seems like a great way to tear yourself up.

So, the take home message:

I don’t really use machines a whole lot (occasionally I will rep out on a hammer strength piece, I am pretty fond of the iso-lateral row) and I don’t use them for clients (especially since we don’t have access to any in our facility), although in some rehab situations, a leg press may not be a bad option. Even though I am not a big fan of machine based training, I could see if you were a bodybuilder, some machine work being of benefit to you. However as always, the basics rule in my book. So squat, bench press, row, pull up and deadlift first. If you want to do some “cute” stuff, do it after the important work is done.

Patrick