An adjustable barbell is a piece of physical fitness training equipment featuring a metal center pole with removable weights at each end. Barbells are most often used for strength training and are lifted or curled with the arms for upper-body training and lifted from the squatting position for lower-body training. Initially, an adjustable barbell used round plates of metal in various sizes to achieve weight adjustment, but with advances in resistance training technology continue to create new type of adjustable weights.
Barbells are one type of training equipment known as free weights, which also include dumb bells, or hand-held weights, and Indian clubs, among others. The first barbells featured a metal pole with weights permanently affixed at each end. To lift progressively heavier or lighter amounts of weight required a different set of barbells for each weight level.
A major advance in weight training occurred in 1902 when the Milo Barbell Co. created the first adjustable barbell. Rather than a weight permanently affixed to the ends of the barbell pole, the first adjustable barbell featured a round plate of metal with a hole in its center. The barbell pole slid through the hole in the round metal plate. The weights were held in place by metal sleeves placed on either side of the round plates through which a hole had been bored so that a screw could be tightened down against the barbell pole, locking it in position.
Round-metal adjustable barbell weights remained the primary method of strength training until the 1950s. At that time, the Universal Weight Machine introduced a new type of resistance-based strength training. The Universal Weight Machine featured various stations build around a center core of stacked metal plates. Each station focused on training for one type of lift, such as squats, curls or bench press.
Free weights such as the adjustable barbell have remained the training equipment of choice for many, even though weight training machines continue to advance in sophistication. The technology for free weights has advanced as well including with the adjustable barbell. An early innovation in adjustable weight barbell technology was to exchange round weight plates with hexagonal weight plates, which are not as prone to roll away when placed on the floor. The type of adjustable weight barbell used in the Olympic games still features round metal plates.
A goal of improved adjustable weight barbell technology is to make it increasingly easier to change the amount of weight being lifted. Some barbell weights also are coated in rubber now, protecting both the metal weight plates and the exercise surface. The adjustable weight barbell pole has been improved as well with various types of grips employed to reduce the chance of dropping the weight and causing injury.