To make horseshoes, you have to hammer iron. And as much as you love to pump your tri's with set after set on the pushdown, you'll never be able to hit them hard enough to forge the big horseshoe-shaped muscles on your arms that you desire. That's because the pushdown isolates your triceps, preventing them from working in conjunction with bigger muscles to lift heavier weights and thereby hammer out thicker horseshoes. The close-grip bench press accomplishes all that and more-working your chest and shoulder muscles while allowing you to boost your bench-press power at the same time.
HERE'S WHAT YOU DO
Set up as you would for a normal bench press, but grab the bar at shoulder width (hands about 14 inches apart). Take the bar off the support rack  and lower it to the lower part of your chest (your sternum) . As you lower the bar, tuck your elbows against your sides so that your upper arms are angled about 45 degrees to your torso at the bottom. Press the bar back up in a straight line.