Pick the Right Tools For The Job
Doing reverse lunges while holding a plate over your head has its place. It can develop some core strength and shoulder stability. But as an exercise to build strength and size it's pretty horrendous.
Likewise, using a kettlebell front rack position places a lot of emphasis on holding that racked position.
This requires a hard brace of your core and a strong and stable spine. But the weight is limited by that position, and not by how much weight your legs can handle.
If you want to grow your legs, then pick variations of reverse lunges that allow you to load your legs the most, without being held back by some other factor. Typically, holding dumbbells or kettlebells by your sides or a barbell on your back are better choices for that goal.
Notice how I've got a forward shin angle and upright torso here. Reverse lunges are extremely versatile. You can easily make minor alterations in body position to shift emphasis.
- By focusing on pushing your front knee more forward and keeping your torso more upright, you can place more load through your quads.
- For more of a glutes and hams emphasis, focus on keeping the shin of your front leg more vertical, and your torso leaning at more of a forward tilting angle (or hips back). This shifts the load away from your quads and makes it more hip-dominant. These work best with kettlebells or dumbbells hanging by your sides.
You also need to consider that a change in muscle emphasis is a result of manipulating torque at your hips, knees, and spine. If you de-emphasize loading on one joint then you place more stress onto another.
Use a more hip-dominant reverse lunge if you want stronger glutes and hamstrings, or if you're trying to take some stress off your knees. And if you want better quads and less load through your low back, then use a knee-dominant lunge. You can also just stick with something in between the two.