In this study, the researches take a look at what happens with pec activation when you bench with your feet up which takes away hip drive.
20 young men
4 years training experience
Same weight used for both variations of feet up vs feet down.
No arch. So no leg drive to assist
EMG used in order to see upper, mid and lower pec activation as well as tricep, anterior deltoid, forearms, abs, obliques & rectus femoris head of the quadriceps.
Muscle activation was higher for every muscle tested by 9-15% when the feet were up.
No back arch in either variation so no leg drive. Therefore, the additional activation did not come from not being able to drive the legs to assist the movement. Otherwise, quadricep activation would have shown on the EMG.
For a more friendlier breakdown of the study with the pros and cons of feet up vs feet down, here is a new Jeff Nippard video that breaks it all down.
This is key right here. When I bench feet down, I can bench 15-20% greater loads at a given RIR. Of course if you bench feet up with the same weight it's gonna be harder, hence greater muscle activation at that load. I'll bet that if they redid the study but started by testing 1rm for both types of bench, then executed with the loads equated, the 9-15% difference would disappear.
@n7340 Check the details of the techniques in the study. With feet down, people were required to be in 90 degrees of knee flexion, the spine and pelvis were required to be in a neutral position, and the butt had to stay in contact with the bench. In other words, no arch, pretty loose setup, and no significant ability to get leg drive. When I wrote about this study, I maxed with both styles as a sanity check, and I benched 5lbs more with feet down than feet up (when it's closer to a 40-50lb difference if I actually do my full set-up and get leg drive). They also measured rec fem EMG, which was basically zero with legs down, further indicating that they weren't getting leg drive. I don't think that that detail makes as big of a difference as most people would immediately assume.
@dawn16 Yes! Once again, studies can take away from common sense at times. Our bodies are more than muscles. Why would you want a little more cheat activation at the risk of injuring your shoulders? Especially in an exercise where too many people experience impingements, bursitis, etc.
@pondsbb The arch is actually to lock the scapulas (shoulder blades) down. By retracting your scapulas before the bench you are preventing from getting those ailments and conditions
@rd1981 What do you mean by natural arch? Because I'm not suggesting you should over arch like some powerlifters... But just laying flat on the bench is bad for a multitude of reasons.
They should have measured vastus lateralis instead. Rectus femoris activity is bound to be low because with concurrent hip extension (as should happen with leg drive) the rectus femoris can't be activated to a high degree, despite the existence of Lombard's paradox. Rectus femoris isn't activated to a significant degree in the squat exercise, for instance.
@n7340 Excellent point, I was going to comment with the same conclusion of activation not equating to output. 1RM's for both types of bench pressing will be quite different I assume.
