Move Forward by Not Moving
Isometric training — creating force against an immovable object — can be a big help in the quest for spinal health, with very little risk for injury. Asking your trunk muscles to resist unwanted forces by simply holding form is a wiser training directive than asking them to create force and make the spine move — for example, a plank or a side plank versus a twisting ab crunch.
Training your body to be stronger in the most difficult part of a lift is a good use for isometrics. Take a deadlift, for example: The bar starts on the floor, and since gravity is doing its best to keep that bar grounded, getting it to move upward is the most difficult point of the lift. Once in motion, kinetic energy helps generate momentum during the rest of the movement. So isometric work helps build power and muscle recruitment where you actually need it most.
You can use isometrics as part of your movement prep or as their own workout entirely. In any case, do moves like these two when your muscles are fresh and ready to produce maximal force in a safe setting.