Balancing Out Arm Strength

How can I deal with my left arm being weaker than my right arm especially with dumbbell exercises? Do I have to lessen the reps or weight for my left arm? If yes, wouldn't that result to my left becoming naturally smaller/weaker
than my right as I gain muscle? (from Ner)

Most people are going to start weight training with their dominant arm being noticeably stronger. This is due not only to the strength developed over time by using your dominant arm more often but from the brain's ability to use that strength more effectively (muscle memory).

Getting both sides as close as possible in terms of strength is desirable not only for the resulting symmetrical look but for the safety and efficacy of all your lifts. With barbell work, your stronger side will just compensate for your weaker. This presents a minor safety issue but, unless the difference is great, shouldn't be a big concern.

It is a good idea to make a concentrated effort to even up the strength capabilities of both sides. Without such an effort, your weaker side will not likely catch up with your stronger. Dumbbell work is the way to do this for your arms.

Always work your weaker arm first. If you can do 6 reps with your left arm, only do 6 with your right arm. Do this for a while and you might be surprised at how quick your weaker arm catches up.

Some people try and speed this process along by doing extra sets or exercises with their weaker arm. I don't recommend this because, assuming you're a beginner, you don't really know what the effects of these extra sets or exercises will be - they could be moving you towards a balance or they could be moving you further away. It is better to stick with your normal routine and retard the development of your dominant arm for a bit.

More on Weight liftting for the Shoulders, Arms and Abs.

JP Clifford