How To Do It 

Stand with your knees slightly flexed.  Bend your torso at an angle of about 45 degrees, keeping your back straight.  Take an over hand grip on the bar with your hands more than shoulder-width apart and your arms dangling straight down from your shoulders.

 Technique

Inhale, contract your abdominals isometrically, and pull the bar straight up untill it touches your chest:   

Return to starting position, exhaling.