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It is common for one arm to be stronger than the other. If you find that this is the case, consider working the weaker arm a little bit more. It is tempting counteract muscle imbalance by increasing the weight your weaker arm. However, this will cause it to reach exhaustion too early. Try to do additional sets with the weaker arm. If you don’t give muscles sufficient time to recover they won’t develop. Because biceps are relatively small and you tend to work them when during other upper body exercises, you need to be especially careful that you don’t overwork them. Exercise them at most twice, preferably once a week.  Because you should not overwork your biceps it makes little sense to work them to the exclusion of other muscles. Try some cardio; it will reduce the fat on your arms, increasing muscle definition. Triceps and shoulder exercises can also improve the appearance of your arm. It makes sense to do back exercises the same day as arms, because many back exercises will also work your biceps. If you exercise these groups separately, you will hinder your biceps ability to recover. You should do your back routine first, because it is always best to start out with larger muscle groups. For maximum muscle growth, you should try to do eight to 12 reps per set. The number of sets you will want to do varies with the level of your muscle development. Try not to overwork you biceps.  Beginners should generally do six sets: three sets of two different exercises. Intermediate weightlifters should do nine sets: three sets of three different exercises. Experts can consider doing as many as twelve sets, varying the ratio of sets to types of exercises. Your muscle fibers will get acclimated to doing the same workouts repeatedly. The biceps are less complex than many of your other muscles, making it difficult to incorporate too much variety. However, you should aim to try a new exercise occasionally and progress to different types of exercises during the course of your workout.  Try one barbell or EZ-bar exercise, one dumbbell exercise, and one machine exercise each workout. Alternatively, try one exercise standing, one seated, and one with the angle of your curl altered by either your body or the bench.  It used to be thought that isolation exercises could change the shape of your bicep. This is now largely dismissed. However, there are some minor muscles in your arm that can be built separately, changing the shape of your arm. The brachialis, which is exercised with hammer curls, runs along the side of the arm to the lower end of your biceps, near the forearm.
Plan for muscle imbalance. Don’t overwork your biceps. Do an optimal number of sets and reps. Vary the types of exercises you do.