In order to develop a successful weight-training program, you need to understand the three principles that are basic to success: intensity, duration, and frequency.

Free weights, dumbbells, and barbells-the most basic strength-training tools- provide an extremely effective type of resistance exercise. Bodybuilders especially prefer them because, unlike machines, free weights can be used in various ways to exercise very specific parts of the body.

Muscle strength and muscle endurance are interrelated and are important in aerobic fitness. Muscle strength refers to power, the ability to produce force at a high intensity for a brief period of time.

In order to avoid accidents and /or injury while weight training, the following safety rules should be followed. *Have a medical checkup prior to beginning weight training or any type of physical activity.

There are a number of weight lifting machines, and most use the principle of variable resistance, which automatically adjusts resistance to provide a constant workout at any speed throughout your entire range of motion.