Principles of Weight Training

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There are many different types of equipment you can use for resistance training. Dynamic exercise involves muscle contractions that result in movement. This is the most common and popular method of weight training and can use weight machines, bar bells, dumbbells, or the body's own weight (push ups, for example). Dynamic constant resistance exercise is the most common form of weight training exercise. During this type of resistance exercise the athlete uses a constant load (barbell or dumbbell) throughout the exercise but the relative resistance of the load varies with the angle of the joint. Maximum loading occurs at the weakest point in the range of motion. Free weights are the most common form of resistive exercise. Barbells are typically standard and Olympic, although there are also specialized barbells available for doing curls, squats and rotator cuff exercises. The benefits of free weights are they can be moved in any direction. Research has shown that free weights can promote quicker strength gains because of the greater demand for balance and coordination, which causes more muscle groups to be recruited (Carroll-Cobb, Liguori, 2012).

Dynamic variable resistance exercise uses special weight machines that change the load throughout the range of motion to put a more consistent stress on the muscles. Dynamic variable resistance exercises put more stress on the muscles at the end of the range of motion, where the athlete has better leverage and is capable of exerting more force. There are many dynamic variable resistance machines on the market, including those made by Ariel, Hammer, Nautilus, Eagle, Marcy, and Kaiser. Weight machines are thought to be safer, particularly when lifting alone. An additional benefit is that specific muscles can be isolated using weight machines.

Some weight trainers use isometric exercise to overcome "sticking points" in an exercise's range of motion. Weight trainers may use a power rack or Smith machine for this type of isometric training. There is also speed loading which involves moving a weight as rapidly as possible in an attempt to approach speeds used in movements such as throwing softball or sprinting. This type of exercise is effective in improving power (the ability to exert force rapidly). High-speed ballistic training using kettlebells is a type of speed loading. Kettlebells are good for exercises such as swings and one-arm snatches. For gaining strength, weight training at slower speeds is superior to speed loading because it allows the muscles to create sufficient tension to cause a training effect. Isokinetic exercise involves muscle contraction at a constant speed, and the isokinetic strength training machines are said to improve power. In additional physical therapists use these machines for ...