Off topic... why are plastic weights lighter than metal?

[OpiateKiller]

So today I go to my friends house to lift, he wanted to get all my maxes to start a program we’re gonna do.

it takes all your PRs and then each week you run reps of percentages of your maxes.

At my gym I use all metal weights.. and he had like the plastic or sand filled ones maybe, not metal plates.

we did bench, squat, deadlift and military press..

I mean at the gym I squat 250... I bench 225, and I weigh 165.

today at his house I was able to get a 300 squat, a 275 bench and a 400 deadlift .. a lot higher than at my gym.

I really don’t think I pushed my self any harder in his garage than in the gym.. is there any other explanation for this? I’m baffled.

 

[BOODIE]

If you mean the cheap weights you can buy with plastic cases (usually filled with sand or concrete) they are less dense.
The weight should be the same despite the material and density though. So I'm assuming it's down the mentality. Your brain might tell you they surely cant weigh as much as metal...cos they're plastic.
But if you can lift and bench more with plastic..and the weights same. Then I'd stick to lifting plastic weights?

 

[nuttynutskin]

Maybe your maxes increased since the last time you tested them? That would be about the only thing that makes any sense.

 

[checktest]

I mean, maybe it was a cheaper set (ebay factory reject special) or mislabeled, though tolerances for weight aren't that hard to make. Usually have to be fairly even as well.

Say 45×6 + 10+5x2 for your squat. 5 pounds off each 45 and maybe a different (lighter) bar might get close, but 50 lbs + on the bench I'm guessing something else. Still would be more than 10% off a weight.

You usually work out with other people (closely)? I bet the different environment, maybe change of your cadence, low key comp could do it, especially with goal numbers like 300. Even if it wasn't a really perceptible push on your end.

 

[OpiateKiller]

I always work our alone and my gym has a lot of people so maybe I’m unable to focus like I did with him?

I guess maybe it is just mentality and competition not really sure it’s odd though. I’m gonna hit the gym tomorrow and try again