Get out of your comfort zone and challenge yourself with heavier weights.
Eight-pound dumbbells are good for a few things like performing warm-up sets, improving muscular endurance and propping open a door -- but when it comes to building big arms, they are essentially useless. Despite any fears or misgivings you have about bulking up with weights, chances are they are completely unfounded. Whether you're a man or woman, it takes a significant amount of work to get big arms. Lifting heavier weights will build muscle that will result in a lean, athletic physique rather than creating the Hulk appearance.
The "Evils" of Muscle
There are a lot of people out there who fear muscle, but there are also a good number who work relentlessly to build it. The individuals in the latter category know what's up. Muscle is more dense than fat, which means one pound of muscle takes up less space than one pound of fat. Generally speaking, the more muscle you have the more compact your body will be at a given weight. Muscle also has something else going for it -- it burns calories. While fat sits idly by, muscle is constantly busy repairing and maintaining itself. This means the more muscle you have, the more calories you burn. A higher metabolism will help you reach and maintain a healthy body weight and composition.
To Get Big, You Have to Lift Big
If your goal is to build muscle and get big arms, then you need to forgo any dumbbells that come in pretty colors and head for the ugly cast iron ones. The process of building muscle fibers takes a considerable amount of effort in and out of the gym. To build muscle, you need to use weights that fall between 67 and 85 percent of your one-repetition maximum. For example, if the most you can use for a biceps curl is a 20-lb. dumbbell, then you should include dumbbells ranging from 13 to 17 lbs. -- or as close as you can get with the available dumbbell weights.
Don't Rush Your Workouts
While dumbbells can be used to get big arms, it's not a project you can rush. Not only do you have to be dedicated to working out regularly, you have to be able to commit a considerable amount of time to your workouts. The National Strength and Conditioning Association suggests completing three to six sets of six to 12 repetitions of each exercise. Your average arm workout may consist of three exercises each for your biceps, triceps and shoulders. If you work on the low end of the set/rep spectrum -- three sets of six reps for nine exercises -- you'll perform a total of 162 reps. If, on the other hand, you work on the higher end -- six sets of 12 reps for nine exercises -- you'll end up doing 648 total repetitions; that's going to result in a lot of time in the gym.
Take a Peak in Your Gene Pool
The potential for big arms, no matter if you use an 8-lb. dumbbell or a 40-lb. dumbbell, ultimately relies upon your body's ability to gain muscle. If you have a genetic predisposition to gain muscle, then you'll likely find that you can perform a lower number of reps, work out less often and still gain muscle. However, if your genes point in the opposite direction, you could spend hours in the gym every week and still not notice an increase in arm size.