The basis of the warm up is to elevate the core body temperature so muscles become more pliable. Muscles are like elastic rubber bands, the hotter they are the more supple they become. It also holds true the colder a muscle is the more difficult it will be for the muscle to contract/shorten and extend/lengthen. It makes sense that if your body is warmer you are less likely to injure yourself while exercising.  Studies show as body temperature rises ultimate strength and greater strain(ability to deform and stretch before tearing begins in muscle) can be found in muscles . The greater the body temperature the greater increase in cellular metabolism which ultimately means more blood flow and oxygen are available to the working muscles.

Warming up also prepares the nerve impulses to be enhanced with more sensitivity of nerve receptors. This sensitivity means the muscles/nerve connection will be enhanced and have a greater ability to fire faster impulses during the workout. Warmer muscles are more apt to produce an increase in range of motion.

There is a physiological benefit as well that many fail to recognize. The body has a delicate system of defensive sense organs called proprioceptors, mainly the muscle spindle and golgi tendon organ.  The muscle spindles are located in the muscle tissue itself and are responsible for letting you know when your stretching the working muscles to far. The golgi tendon organ as you might have guessed is a tendon organ that senses when an excessive amount of tension develops. When tension is too high the golgi organ shuts off muscle contraction to protect the working muscle. These sense organs are elevated through proper warm ups.

Last but not least there is a mind-muscle connection that needs to be addressed. Going straight into heavy exercising can have detrimental effects on performance by not preparing the mind properly. Warming up is the vehicle of relaxation and concentration just before intense exercise.                 

So the next question is what is a warm up? Any light cardio movement such as a stationary bike, treadmill, elliptical, and walking in place for 3-5 minutes will be enough to raise your temperature.

Dynamic warm ups can also be a valuable tool against injury. These movements mimic whatever exercise your about to perform except on a much lower intensity. For example:  a dynamic warm up of the bench press would be 1-2 light sets of 10-20 reps with a weight that feels fairly light even upon reaching the last rep. If you want fewer injuries always remember to warm up properly.