"The Leg Press is Useless!"
The coaches and trainers who make that claim remind me of this saying (attributed to Albert Einstein): "If you judge a fish by its ability to climb a tree, it will live its whole life believing it's stupid."
In the leg-press-is-useless scenario, the coach is probably looking at the leg press's ability to serve a very specific purpose, like improving the barbell back squat. In other words, he really doesn't understand how it could be useful in the proper context, like for pure bodybuilding purposes.
First, we need to establish some guidelines about proper leg pressing, and then we can talk about the usefulness (or uselessness) of it from there.
Proper leg pressing is a thing. There's a right way and a wrong way to do it. It's not quite as simple as just lowering the weight and pushing it back up.
1. Establish your active range of motion.
This is done by lowering the weight, but not so far down that your butt comes off the seat or your lumbar spine goes into flexion (rounded).
This is especially important as loading increases. Your discs don't approve of your ass coming off the bench and your low back rounding. They end up eating a metric butt-ton of tension and torque. They weren't made for that. So stop doing it.
2. Choose an appropriately challenging weight.
Don't train with your ego and load the leg press up with eleventy billion pounds, or have other clowns sit on top of the machine to garner more attention as you do two-inch range of motion reps. Or if you do, at least get it on video so we can watch.
The interesting point about the excessive loading and partial range of motion is that you actually end up with less internal loading. A full range of motion with less weight will increase the internal loading on the muscle in comparison to a partial movement done with more weight.
3. Don't fully lock out the knees.
I know the knees and joints are actually made to lock out, but not with 1,000 pounds on top of them. The reason a non-lockout is important is because when you lock out, the tension will shift from the quads to the joints and connective tissue. After all, that tension and weight distribution has to go somewhere.
Once you lock the knees out fully, then the quads are in a somewhat relaxed state in contrast to if the knees were in a small amount of flexion. You want a soft-knee, slightly bent at the top.
Now, intelligent leg pressing involves an active range of motion that's deep enough to create superior internal loading, but not so deep that you risk injury by invoking lumbar flexion. Then, of course, a soft knee at the top of each rep.
So How is the Leg Press Useful?
If you're trying to make the claim that leg pressing is great at building a squat, then you'll lose that argument. But here's where it CAN be helpful:
Starting Deadlift Strength
The leg press helps to improve a deadlift that's weak off the floor. The key is to make sure you're using the same foot placement that you use for deadlifts. From there, mimic the start of the deadlift and do paused leg press reps instead of piston-style reps.
The Sumo Leg Press
This has been a longtime favorite of mine for loading up the glutes and hamstrings.
Simply put your feet as high and wide as you can (comfortably of course) on the platform. This is a great movement for the glutes and hams in the lengthened position, but if you add bands and stop quite a bit short of lockout, you're going to come to a real understanding of what a massive booty pump really feels like. Pour these on for high-rep sets, like 25-30.
Getting the feet very close together and low on the platform will cause a significant degree of knee flexion, forcing the majority of the tension directly onto the quads.
John Meadows recently made this point: the leg press is on a fixed plane, so your form is very consistent with it. You can't get all cheaty outside of reducing the overall ROM. So long as you're training with some personal integrity on the range of motion, you get consistent feedback of your progress and will be able to track your progressive overload.