At first glance, the differences between a curl bar and a dumbbell are easy to spot. The size, shape and color of dumbbells are plenty compared to the one variety of curl bar. Although both are resistance-training tools, the structural characteristics of each lead to training variations. These variations include the types of exercises and workout techniques you can do with them.
The Long and Short of It
A curl bar is a 4-foot long piece of steel. The Olympic curl bars have 2-inch diameter ends to hold onto Olympic-sized weight plates. The diameter of the middle of the bar is 1 inch for an easy fit into your hands. A dumbbell is like a mini-barbell. Approximately 8 to 12 inches long, a dumbbell has a 6-inch long piece of steel to hold when you exercise.
Carries its Weight
Another difference between a curl bar and a dumbbell concerns weight. An Olympic curl bar weighs 18 pounds without the addition of weight plates. Weight plates are added at increments of 2.5 pounds to increase the amount of resistance. Dumbbells are available in many styles. An adjustable dumbbell is a handle onto which you slide weight plates. The handles vary in weight between 1.5 to 7 pounds. Other types of dumbbells are fixed weights and can weigh between 1 pound to 100 pounds, usually in increments ranging from 2 to 5 pounds.
A curl bar resembles a semi-flattened "W." The wavy bar allows for a hand position that is near neutral but on a slight angle for improved wrist comfort. You use both hands on a curl bar, similar to the way you would use a barbell. Dumbbells may have round heads, hexagon-shaped heads or weight plates on the end, but the handles are the same. The dumbbell bar is straight and is held in one hand.
What's The Point?
The curl bar is limited to exercises that use both hands. A dumbbell is not. For example, you can perform a dumbbell chest fly, but not a curl bar chest fly. Since you hold a dumbbell in one hand, you can position your hand in any way necessary for exercises. Dumbbells are used for single-handed exercises such as shoulder presses, hammer curls, triceps kickbacks, back rows and single-leg deadlifts. A curl bar is limited to a few hand positions: up, down and slightly turned in. The bar is useful for exercises in which you want a heavier weight and need the support of both hands, for example, during a biceps curl or a lying triceps extension. You can hold both dumbbells or a curl bar for lower body exercises such as squats, deadlifts, lunges and calf raises.