Elbow position, use of abdominals

[jsraaf]

Couple basic lifting issues I'm wondering about lately:

Elbow position during incline DB press
If you keep your elbows tucked in close to your chest, as opposed to away (with upper arms nearly perpendicular to chest), does it affect involvement of pec and/or front delts?

Use of abs during lifts
In general, when lifting (especially heavy, or on squats/leg presses, etc.) are we wanting to "suck in" our abs while tightening them during the lift?

I have noticed an... expansion... of my lower abs recently. I particularly notice it during it when doing a leg press on my smith machine (on my back, legs vertical & pressing upward).

Thanks in advance!

 

[stevie]

when squatting/leg pressing, you want to take a very deep breath on the negative portion of the lift, either immedeately before or during the movement. Either way, your lungs should be full in the bottom position. You also want to hold your abs 'tight' throughout the lift. Both these will provide strength to your midsection/back keeping you much safer from harm.
Preventing your arms from flaring out away from your body during bench will take stress of the shoulders (which is a good thing). However, keeping the arms too close to the body will make the exercise a 'close-grip bench press' ie mainly working your triceps. There is a balance. The problem is it is hard to explain the correct position using words.
This link provides some very good information:
bench press tequnique 1
bench press technique 2
bench press technique 3