Red Delta Project on lower back isolation exercise

I just watched this video posted by Matt (Red Delta Project) on his channel a few months ago.

Matt contends that the lower back is more like a joint, so saying "work the lower back" is like saying "work the knees". Just as "feeling the knees working" is a sign that something is wrong with your knees (joints), "feeling the lower back working" is not a good sign either. Matt does teach exercises that target the posterior chain, which includes the lower back, but at the same time, he also teaches that you should engage your lats, glutes, and hamstrings - so that force travels through the lower back instead of being concentrated on the lower back.

One question that often comes up is What calisthenics exercise is an alternative or replacement for the barbell deadlift?. Matt does not mention it in the video but I think the majority of the people who asked Matt about lower back isolation exercises were thinking about the barbell deadlift. The barbell deadlift is believed by quite a few people to be a lower back exercise. The muscles that actually do the heavy work in the deadlift are the glutes and the legs, with emphasis on the hamstrings although other leg muscles such as the quadriceps also contribute. What we think of as lower back muscles are the spinal erectors and transverspinalis groups - both muscle groups just work to stabilize the spine when the deadlift is done in proper form. If you mess up and try to use the spinal erectors and/or transverspinalis to lift the barbell, you'll probably injure your back - I unfortunately learned this from direct experience.

There was a time that I too wondered what calisthenics exercises might be good substitutes for the barbell deadlift. This was when I still believed in the deadlift as the best low back exercise ever invented by humankind. However I eventually realized that the deadlift is really a good dynamic exercise only for the leg and glutes - because if you attempt to use it as a dynamic exercise for your low back, you could very well destroy your lower back instantly. The deadlift is at best a decent isometric (static) exercise for the low back. Some people have a good reason to practice the deadlift. If you care more about "lower back strength" than, say, achieving a double or triple bodyweight deadlift, you probably don't need to practice the barbell deadlift

The Red Delta Project channel and other Youtube channels like Knees Over Toes Guy have videos teaching posterior chain or "lower back" exercises. But if you pay close attention, most of those exercises do not involve dynamic movement of the lower back itself, but instead have you keep the back fairly straight and have other muscles - typically the hamstrings, glutes, hips, and/or lats - do the dynamic work.

One dynamic exercise for the lower back that seems to be in fashion at the moment is the Jefferson Curl - however just about all the coaches that advocate that this exercise advise training with light weight - this is not an exercise in which you should be working towards a double bodyweight lift! In fact, just about all the advocates say you should start with no external load at all. Another dynamic exercise that has always been in fashion are side bending exercises such as the one advocated by Knees Over Toes Guy. Knees Over Toes Guy posted their latest lower back exercise video here, including the side bending: