@mayblin I recommend Stuart McGill to everyone. He ran a low back research lab at a Canadian university for many years and has several books on low back problems, the core and athletic performance. His "McGill's Big Three" is quite famous as a safe effective core foundation routine. His book The Back Mechanic is for the lay person with back pain but you don't need to have back pain to use his methods and ideas. The book helped me quickly greatly improve low back and hip pain/weakness that had been going on for 45 years despite many many attempts to solve the problem. I do a number of core and theraputic exercises but McGill's are the essential ones.