It may sound too good to be true, but you can really add nearly an inch to your arms after a few short training sessions. Do this routine once a week. You'll walk out of the gym with a huge pump, and in a few weeks, you'll have permanent growth.
How to do It
Alternate band pushdowns and band curls. Do the first 30 seconds, then immediately do the latter for another 30. Rest no more than two minutes. For the first two weeks, perform two sets of each move. In Weeks 3 and 4, three sets. In Weeks 5 and 6, four sets. You should build a solid inch of new muscle in around six weeks.
Grab an exercise band and tie it to the top of a squat rack or cable machine column. Grab the middle of the band with both hands and tuck your elbows to your sides. Extend your elbows just like in a cable triceps pushdown. Try for 60 reps in 30 seconds (if you can't do it, use a lighter band). It's OK if you break form and rock back and forth a bit.
Anchor the band under your feet, holding the other end with both hands. Curl for 30 seconds, aiming again for 60 reps.