type of exercise equipment used in weight training. Specifically, dumbbells are
weights used without exercise machines. Dumbbells are sometimes also called
hand weights and free weights those used  free  of such equipment. Most
dumbbells are designed with a narrow bar in the middle and two wider discs at
each end. Some dumbbells are very light in weight (only a few pounds) while
others are very heavy (50 pounds or more). They can be fixed in weight or
variable. Specifically, dumbbells can vary in weight due to discs that can be
added or removed from the bar by quantity and size (weight). In addition, dumbbells
can be used individually (a dumbbell in one hand) or in pairs (one in each
are very useful for strengthening muscles; in particular, for concentrating on
specific muscles for each type of exercise.
dumbbells are simple devices for lifting weights when compared to the
complicated machines and devices used in the modern-day gymnasiums and weight
rooms, the dumbbell is considered by sports enthusiasts and sports researchers
alike as one of the most effective ways to strengthen muscles and produce a
powerful and muscular body.
Jan Todd, a professor in the Department of Kinesiology and Health Education at
the University of Texas (Austin), teaches classes in sports history. Todd, the
author of From Milo to Milo: A History of Dumbbells, Barbells, and Indian Clubs
(and a former world-class power-lifter and member of the International
Powerlifting Hall of Fame), states:  Almost all sports scientists consider them
[dumbbells and barbells] superior to machines for building athletic power.