These days everyone has heard of “activating their core” before lifting anything heavy, but this is often poorly understood. It doesn’t just mean pull in your tummy. Often what people pull in is actually the diaphragm (hollowing under ribs) which doesn’t support you back. Correct instruction should start with pelvic floor contraction (pretend you’re trying to stop yourself going to the toilet mid-stream) and spread up into the lower abdomen (like you’re trying to fit into a tight pair of pants). Your breathing shouldn’t change, and the rest of your abdominal muscles (6-pack, obliques etc) should be soft and relaxed. This can help some people feel safer when they bend, although other patients find the abdominal bracing causes more compression and pain.
New research has compared the effectiveness of this to other exercise techniques, and has found that while core stability exercises ARE effective, they are no MORE effective than less specific exercise like walking, swimming, riding bikes or going to the gym. The most effective exercise is the one you’re going to do, so get moving and make it something you enjoy!