I'm not sure what Scott says when he says "keep your core tight"

I have quite the belly fat so I can't exactly see if I'm keeping it tight. Is it like sucking in your stomach a little?

Kymond,

Yes, it is flexing and keeping the muscles of your stomach and lower back tight as you do exercises that leverage your core like squats, etc.

John

Its actually complicated. This applies more to heavy compound exercises and less to isolation exercises. Ideally you want to take a big breath before lifting the weight, fill your belly with air and at the same time suck your belly button in. This creates a lot of tension in your core, which is what keeps you stable. The ab muscles will act as a type of pillow which protects your spine from injuries.

But for smaller isolation exercises like tricep pushdowns, the core will activate by itself as need. You just have to make sure you are flexing the abs and you are keeping your spine aligned at all times.

Kostas

Adding to Kostas' point, the idea is to create a cylinder effect with your entire core musculature (abdominal wall, back, etc.). There is a big difference in trying to flex the abs for a photo and using them to help brace the spine - think of how you would react if someone tried to give you a shot to the gut. Typically that reflex / reaction is very similar to how you would want to orient your core in terms of lifting / tightening.

Google terms like TVA, Core Bracing, Spinal Bracing etc. That should help.

Eric

basically suck in the gut and take a deep breath with every repetition, even on isolation exercises contrary to whispers belief, your abs may contract but it still means you should make an attempt to control it, not to be rude or anything but the key is to try and get your belly button ballsack and butthole to suck into your stomach... try and master the movement of each part then do all 3 and maintain that throughout all movements especially deadlift and squats, it will take alot of pressure off your lower back and put it directly into other supporting muscles such as rectus abdominals and hip flexors which in some people are hard to trigger during these exercises for that exact reason... hips linked to sucking in your sack and hamstrings linked to your hole and rectus abdomins linked to your belly button... again i apologise for the rude language but i saw no other way to put it unless you all want the scientific names and im damn sure you dont want a demonstration

I agree about the feeling of sucking your ballsack up! From a physio perspective I always tell my clients, "its the feeling of stopping urine mid flow." That seems to do the trick and I have actually seen this on diagnostic ultrasound improve the contraction of TvA. In terms of core contraction what many people have trouble doing is actually contracting TvA without contracting their abs glutes etc.

every little muscle is still a muscle that needs to be developed :3 its how we grow...