Over time your muscles will become use to your workout routine, so it is important to mix it up every so often (usually every 4 weeks). This can be done through increasing volume, weight or changing the exercise routine completely. The bicep workout I am presenting to you consists of several basic movements combined into one set, hitting the brachialis (separate muscle, but when developed, will give the biceps a larger appearance) the long-head and the short-head of the bicep, with very little rest time to improve muscle breakdown. Remember, leave your heavy weight ego outside the gym and use proper form and full range of motion for proper results!
1) Perform 4-6 reps of barbell curls with form (use a weight that you reach failure after 4-6 reps), then take a 10 second rest before starting the second part of the workout.
2) Perform the same barbell curl but with a lighter weight (usually 10kg less) for 6-10 reps, taking your final 10 second rest before moving onto the next part of the workout.
3) Perform dumbbell hammer curls (alternating arm after each rep) aiming to get 8 reps with each arm. Without rest, perform dumbbell supination curls (alternating arm after each rep) for 8 reps per arm. Without rest, perform wide dumbbell curls (alternating arm after each rep) for 8 reps per arm. Complete this for 3 rounds. If necessary on the second or third round, reduce the weight.
As a finishing exercise, perform 3 sets of 6-10 reps on the bicep curl machine.