Resistance exercises are part of resistance training, which is a type of strength training. Unlike cardiovascular training, which is about increasing respiration, this kind of training focuses on muscle size and strength. Resistance training can be done using the body parts in opposition to each other or another static force--or by using weights or machines. There are two main categories of resistance exercises: isotonic in which a body part is pushing against another force, and isometric in which the body part is holding, or resisting a force.
Resistance is simply putting a load on a muscle, making it move against a force. That force might be external, such as a weight, or it might be internal, like another muscle in your body. When a muscle tries to move, but encounters a problem (resistance), small tears occur in the muscle, which are then rebuilt and actually overbuilt to handle the next similar encounter. As a result, muscle tissue gets bigger and more toned.
This kind of exercise requires virtually no movement of the muscle and can be done with no equipment. Contracting a muscle as you sit is a form of isometrics. Pushing the palms against each other, for instance, is one isometric exercise. The associated bones are not moving. Neither are they moving, say, if you are trying to open a stuck window. The muscles are working, but it is not causing movement. Thus, this kind of exercise does not require equipment, though a doorframe or the floor may be used. Because they do not require movement, isometric exercises can be done in a relative small space. These types of exercise can be performed in a chair at work, in a car or on an airplane. Isometrics also build muscles used for many everyday functions, such as carrying and holding.
In contrast to isometric exercises, isotonic exercises involve movement. The muscles get shorter during the concentric phase of the exercise and lengthen during the eccentric phase. Weights or bands provide the resistance. In the classic bicep curl, lifting the weight causes the muscle to contract and lowering it extends the muscle. The arm bones move. Other isotonic exercises include shoulder raises, squats and chest presses.
Adding Weights and Machines
Progressive overload is the theory that the amount of weight resisted is increased each session. This is the most effective type of resistance training. It can easily be done with free weights or exercise machines. Free weights are inexpensive and, if used properly, can be safe. Machines are more costly, and take up more space, but offer more variety of movement, more fluidity of movement and less risk of dropping the weight on your toe.
Advantages of Resistance Exercises
Researchers at Bispebjerg Hospital have found that resistance training has clearly increased muscle mass in the elderly, who may be limited in what kinds of daily exercise they can do due to previous muscle degeneration. Many resistance exercises don't require expensive or large equipment. For this reason, those with lower incomes or busy travel schedules can perform the exercises at home or in a hotel.
- gym image by Mat Hayward from Fotolia.com
This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.