Bodybuilding Exercise

Do a Proper Warm Up before starting a Bodybuilding Program
It is important to warm up before beginning your bodybuilding program for two main reasons:
It reduces the chances of injury.
It will improve your performance.
Here are a few quick reminders of why you should do this.
Muscles respond better to exercise if they are properly prepared for the coming work­load. Warming up increases blood flow to the muscles and lubricates the joints because the fluid surrounding them becomes less viscous so the joint can move more smoothly and efficiently. At rest, muscles receive only about 15% of your total blood supply, but during exercise the requirement for fuel and oxygen sharply increases and they may need up to 80% of the total blood flow to meet the demand. Obviously, it takes time to re-route the blood, and this cannot be achieved efficiently if you omit the warm-up and start exercising vigorously.
Warming up also improves the elasticity of the muscles, enabling them to work harder, more efficiently and for longer before they fatigue, as well as allowing nerve impulses to be transmitted faster.
Finally, warming up also prepares you mentally for the work ahead; it increases your arousal level and motivation. Performing one or two warm-up sets with light weights acts as a mental rehearsal and means that you can perform your subsequent heavier sets more effectively.
Warm-up components
The time taken on this part of your workout depends to a large extent on the temperature of your surroundings - the cooler the environment, the longer it will take to raise your body temperature. Your warm-up should include the following three components.
An aerobic activity that raises your body temperature and leaves you mildly sweating. This should be performed for 5-10 minutes and be continuous and rhythmic in nature - for example, stationary cycling, treadmill walking, gentle jogging, stepping or rowing.
Mobilization of the major joints. This could include movements such as arm circles, knee bends and shoulder circles which take the joints through their full range of movement. These are not stretching exercises as they are continuous and do not increase the range of movement.
Warm-up sets with light weights and high repetitions. Never embark on your working sets straightaway because your muscles won't be properly warmed up and you there are chances of injury. Start with 1-2 sets using very light weights (around 40-50% one-rep max), for 15-20 repetitions to warm up the target muscles, ligaments and joints, and to rehearse the action to be performed.

To Stretch or Not to Stretch?
For years it was thought that stretching before strenuous activity would help prepare the muscles for exercise and reduce the risk of injury. However, more recent research suggests that stretching before you start training is unlikely to benefit your performance and may even be detrimental. Ironically, strength is lower following pre-exercise stretching compared with no stretching at all. In addition pre-exercise stretching will not prevent post exercise soreness or tenderness. It is now believed that stretching is best kept to a minimum prior to strength and power training. An active warm up(such as treadmill, exercise bike, steppers), followed by 1-2 warm up sets with light weights, is more effective. For example before performing bench presses, do one or two warm-up sets with a light weight that you can comfortably manage for at least 15 repetitions.