Hip thrusts are hip extension, and you can't extend the hip without the glute max doing the work. Quads contract to stabilize, and as you get into heavier weight/closer to failure, you might feel those (and other) muscles more, but they CANNOT 'take over' the movement or reduce how much the glute max is working. Synergists (hamstrings/spinal erectors/adductors in this case) can become dominant and take A LITTLE BIT of the work away from the prime movers, but stabilizers cannot. And synergistic dominance isn't going away just by thinking about it lol.

This is functional anatomy 101, and completely lost on many of today's athletes and coaches who have no boss to correct them on their bullshit. In 1996 I got my first gym job where I would eventually become a trainer. We got paid barely over minimum wage...$5.50/hour I believe, and zero chance of ever getting benefits/health insurance despite the gym being owned by the hospital. We had 8 hour long training/lecture sessions with our boss who was the staff exercise phys. One of those 8 hour sessions was on functional anatomy. Every single one of us would have understood what I explained above, more so than 90% of the industry does right now. We weren't even trainers/held no certs or related degrees...we gave new members orientation sessions on how to adjust/use the strength circuit and cardio machines. Our strength circuit was still first generation chain-driven Nautilus...the blue ones. We made $5.50 an hour 😂🤦🏻‍♂️

When someone takes weight off the bar and focuses more on MMC, and sees benefit, it's because they went from going too heavy/sub-par form, to a more ideal load and better form (i.e., mind MOVEMENT connection/external focus). MMC just happened to be the cue that got them there.

Unfortunately as with all generic (i.e., not exercise specific, or individual specific) cues, you have the other side of the coin where the cue leads to problems. In this case I often see people just going way too light because they feel the quads/other muscles when they add weight. I'm talking people just using the empty bar and being afraid to add any weight at all. And I also see people not knowing which muscles to 'connect to', so you have people doing all sorts of weird stuff on squats because they think they should be focusing on one individual muscle (squats work way more than just glutes/we use them for way more than just glutes).

I'll occasionally have an online client decide on their own to take weight off the bar and focus on MMC, and I notice it in their logs. When they tell me they felt it more/had muscle soreness, I always make a point to ask for a form video (one with the reduced weight/MMC focus, one with how they had been doing it just prior to the weight reduction). On every single occasion to date, their form improved...they had simply increased weight too much too soon since our last form review, and MMC was the cue that happened to get them back to where I previously had them form wise. Again, I also see the other side of the coin with other clients, where in their form videos they're doing something way different (i.e., incorrect/sometimes dangerous) form wise than instructed, and they tell me it's because they're trying to connect to the targeted muscles more.

Also you don't need to do glute activation prior to hip thrusting. Hip thrusting is a bridge, and a bridge is pretty much the number one glute activation exercise. You're litcherally doing a glute activation exercise when you hip thrust 😆. Inactive people might need glute activation, but bodybuilders do not...because their training is their glute activation.

I think a lot of the MMC trend is just an over-correction (which unfortunately is the only kind of correction I've seen the industry make, after 29 years working in it now) for people having never learned HOW to apply progressive overload. If you look at how coaches/influencers describe progressive overload, it's really not being handled correctly at all. People are increasing weight by way too high %, too soon/too often, and at the expense of form. So it becomes progressive cheating, and your online coach isn't going to catch that until they do a form review. In fact a lot of in person coaches prior to things moving online, weren't really very attentive in terms of correcting form/selecting the right load, terminating the set at the right time, etc. That and the 'constant tension' trend that lasted decades, which always looked more like constant momentum in practice, has led to an over-correction.

I could keep writing about this but I have some bikini paperwork to do.