Let's look at how core exercises, or even seemingly harmless things like walking or tying your shoes with muscle imbalances can cause back pain.
All human movement causes the vertebrae in the spine to bend, twist and compress naturally, but when there's a lack of support for the spine, it leads to excessive motion in the vertebrae, causing degeneration to the discs and nerves that pass through them.[3]
Nerves in the spine react with pain signals to the brain[4], setting off the spinal protection mechanism, and putting you in the "pain cycle".
Movement and exercise are only therapeutic for the spine if the deep core is engaged properly to support it, but this is not possible with a muscle imbalance.
[3]https://www.physio-pedia.com /Lumbar_Instability
[4]https://www.ncbi.nlm.nih.gov /pmc/articles/PMC3438523/