From what my sport doctor and physio explained, during a hyperextension movement, when you've doubled over and your head is pointing at the ground, you're openi

From what my sport doctor and physio explained, during a hyperextension movement, when you've doubled over and your head is pointing at the ground, you're opening the spine up, fluid moving between discs and cartilage, etc. In a full hyperextension, you're compressing in the opposite flexed direction. If there's misalignment anywhere in your spine, you might be increasing your risk of exacerbating the issue. The trouble with bro science is that those lifters may never have actually had the problem you're experiencing, and if they had, may not have had it in the same way that you have. Core strengthening exercises are good in general as stronger/thicker muscle better protects the connective tissue providing backup support for your joints. It's a reason some athletes can tear ACLs and such and walk around normally while a normal person might end up debilitated. Please get a referral from a sports medicine specialist for a physio. Even if you go only once, have someone give you strategies for strengthening and protecting your back the safe way.