Dumbbells are commonplace in the gym; they are one of the most popular pieces of gym equipment that are used for strength training purposes. They are distinct from the barbell in that they can be used one-handed, and that it can be used as a way to develop and test balance in a way that the barbell cannot. Due to this, they have become a staple of the gym, and one is likely to see at least a few of these in every home or commercial gym they come across.
While some exercises involve the use of dumbbells while standing, especially those that mirror the motions of exercises involving barbells by holding equal weight dumbbells on both hands, most exercises that use these, especially those that involve dumbbells of much higher weights, a stool is often utilized to help the gym-goers keep their balance as they use all of their energy on lifting heavy dumbbells with their arms.
The stool might seem like such a small detail, but it is actually quite important in that it allows the user to get the most out of the exercise. When the user is seated on a stool, he has to focus less energy toward keeping in balance, and thus allows for the dumbbell to make the user exert as much arm strength as they can to lift it. It also allows one to avoid any risk of falling out of balance with one dumbbell in hand, which is a real consideration for dumbbells of higher weights.