Dumbbell

A dumbbell is a piece of equipment used in weight training. It is a weight that is held in one hand. Dumbbells therefore normally come in pairs. There are two main types of dumbbell:

• Adjustable dumbbells consist of 14 inch (35 centimetre) long steel bars that are one inch (2.5 centimetres) in diameter. They look like miniature barbells. The centre portion is engraved with a crosshatch pattern (knurling) to help users get a good grip. 1 to 40 kg of cast iron weight disks (plates) are slid onto the outer portions of the dumbbell to obtain the desired total weight. These weights are secured with clips or collars. A "spinlock" dumbbell's outer portions are threaded, and the collars are large nuts that screw on and secure the plates through friction.

• Fixed-weight dumbbells are weights created in a dumbbell shape. Expensive varieties consist of cast iron coated with rubber. Cheaper versions consist of a rigid plastic shell that is filled with concrete.

Exercises that can be performed with a dumbbell include:

• Bench press
• Bicep curl

Disambiguation

The Dumbbell Nebula is a planetary nebula (M27), which is shaped like a dumbbell.