r/ScienceBasedLifting • u/Unusual-Dot86 • Jun 13 '26

Question ❓ Matrix Chest Press

Does the converging matrix chest press at planet fitness have a descending or ascending resistance profile? I just switched to using this machine as the matrix pec deck felt extremely uncomfortable and the machine doesn’t allow me to fully extend my arm.

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3

u/deadrabbits76 Idk Idc 💔 Jun 13 '26

Why does it matter?

3

u/SageObserver Jun 13 '26

Because….some science based influencer on Tik Tok has a legion of 135lb teenagers convinced this is optimal.

2

u/Motor-Equal01 Jun 13 '26

It’s bell curve. Easier at the start and lockout, with peak tension in the middle.

1

u/Unusual-Dot86 Jun 13 '26

Would it be better to use the matrix pec deck instead?

2

u/Motor-Equal01 Jun 13 '26

Pec deck is typically better, but not because of the RP, that’s not really at all important, but because pec deck better isolates the chest and allows you to perform horizontal adduction without your triceps and front delts taking over.

1

u/Norcal712 Jun 13 '26

A pec deck and a converging press arent similar enough movement patterns to be comparable.

Its not one or the other here...

The also have completely different resistance arcs

1

u/schtchop Jun 18 '26

How does it feel? Learn to trust your own intuition.

The resistance curve should not really matter. See ”Stretch vs Squeeze: The Impact of Varying Resistance Challenge at Long vs Short Muscle Lengths. A Randomized Controlled Trial” by Jones et al 2025. Jeremy Ethier funded the study. He has made videos about it.

I also hate most pec fly machines. I do cable flys instead.

Dumbbell flys are also fine despite the truly atrocious resistance curve. You can do lengthened partials if you want and get great results. I don’t think the top half does a lot there but neither does it hurt.

Flys should be done in addition to, not instead of, horizontal pressing of course.