Free weight poundage equivalent of Smith Machine

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12-26-2005, 12:44 PM
d74mr

Free weight poundage equivalent of Smith Machine

I train by myself and find the Smith Machine useful b/c I don't have a spotter.

How much weight does the Smith Machine deduct from the weight I'm lifting? I'm assuming that it must deduct some as when I let go of the bar in the Smith Machine, it doesn't drop as quickly as just a plain old bar.

So, for example, if I'm benching on Smith Machine with 40kg on each side, what would be the equivilant on free weights? What about dumbells?

I did use the search function and the only thing I could come up with is that the Smith Machine bar weighs 15lbs as opposed to the 45lbs of free weight bar.
12-26-2005, 01:01 PM
Flexor

The smith machine isn't really a machine. Its just a barbell that is restricted to a single plane of motion. Although this is considered to stabilise pressing movements, it can actually place more strain on your joints because of the restricted movement. I would say you could lift more without the smith machine because additional muscle groups would be recruited to help stabilise and lift the free weight. The fact that the weight drops slower is a safety feature and I don't think it indicates you are pressing less mass.

I guess the only way you can find out is by trying free weights instead..., but its unlikely the free weight would be significantly different. If you were using a machine bench press with levers it would be a different story.

When you use machines, the load of the plates is put through a mechanism so that you don't physically move the weights. The machine moves the weights by a series of levers, because you have applied a force to one of these levers. The additional levers that have been added alters the moments and leverages involved with moving the weight, so you can "lift heavier" when you use a machine. In actual fact though, to lift the bar you must overcome the resistance of the machine rather than the load applied by the weights. The resistance you overcome will be equal to the resistance of a certain free weight for the same number of reps, its just that free weight will weigh less than the one you put on the machine.

The weight you put on a machine is usually higher than you could do with free weights, but its hard to say how much it would differ by without performing calculations based on the machine's specifications.
12-26-2005, 03:47 PM
Benches505

The weight you will move with free weights as opposed to the smith machine can be very different. The smith machine balances the weight for you and requires less stabilizer muscles to do the lift.

I can do 6 reps with 315 behind the neck/ military press with free weights

I can rep the same weight until I'm blue in the face on a smith machine. to put it more into perspective I'm sure I can get 15 reps with the smith machine on the same movement. So I would venture to say smith machine weight=50% of free weight weight.
12-26-2005, 05:39 PM
timvds

Quote:

Originally Posted by Benches505

The weight you will move with free weights as opposed to the smith machine can be very different. The smith machine balances the weight for you and requires less stabilizer muscles to do the lift.

I can do 6 reps with 315 behind the neck/ military press with free weights

I can rep the same weight until I'm blue in the face on a smith machine. to put it more into perspective I'm sure I can get 15 reps with the smith machine on the same movement. So I would venture to say smith machine weight=50% of free weight weight.

ummm. I was curious about this too. Please don't tell me im benching 165...

:?:
12-26-2005, 05:41 PM
Benches505

I'm about to head off to the gym to do shoulders... I will put it down to an actual test and report the results when I get back.
12-26-2005, 06:07 PM
timvds

Quote:

Originally Posted by Benches505

I'm about to head off to the gym to do shoulders... I will put it down to an actual test and report the results when I get back.

damn bro, thanks.
12-26-2005, 08:52 PM
Benches505

Smith machine worked out to about 40% lighter with the same weight. 7 reps on free weights as opposed to 12 on the smith with the same weight.

This applied to behind the neck military presses.
12-26-2005, 09:03 PM
Zapp

Quote:

Originally Posted by Benches505

The weight you will move with free weights as opposed to the smith machine can be very different. The smith machine balances the weight for you and requires less stabilizer muscles to do the lift.

I can do 6 reps with 315 behind the neck/ military press with free weights

I can rep the same weight until I'm blue in the face on a smith machine. to put it more into perspective I'm sure I can get 15 reps with the smith machine on the same movement. So I would venture to say smith machine weight=50% of free weight weight.

If the smith machine was 50% of free weight, that means if you could bench 350 using free weight, you should be able to bench 700 lbs on the Smith. Not gonna happen bro.
12-26-2005, 09:32 PM
Benches505

Quote:

Originally Posted by Zapp

If the smith machine was 50% of free weight, that means if you could bench 350 using free weight, you should be able to bench 700 lbs on the Smith. Not gonna happen bro.

good point. It must vary from % of max to just reps. Since doing the extra 5 reps really translates into an extra 50lbs if you put any stock in those rep/max calculators. So the actually percentage difference would be closer to 15-20%.
12-26-2005, 09:34 PM
Zapp

Quote:

Originally Posted by Benches505

good point. It must vary from % of max to just reps. Since doing the extra 5 reps really translates into an extra 50lbs if you put any stock in those rep/max calculators. So the actually percentage difference would be closer to 15-20%.

There ya go. Thats about the % I was thinking.