Human muscular system, along with skeletal system presents a system for performing all sorts of motions and movements. Even though injuries of this system might not seem so dangerous (broken bone and torn muscle are not the same thing as cardiac arrest), those injuries prevents us from moving and performing all daily activities.
Muscles consist of muscle fibers, which are created from muscle cells. There are two major types of muscles, smooth and skeletal. There is also a cardiac muscle, which is a sort of hybrid of those two mentioned types. Skeletal muscles are those engaged in the motions and movements, while smooth muscles are found it the inner organs, usually the walls of those organs. Of course, most visible are skeletal muscles, which are mostly placed alongside the bones, and are connected with tendons to those bones. Their contraction helps us perform all possible motions. It is done with the anaerobic and aerobic process. Aerobic process is done with the help of oxygen. This type of contraction is used with slow contractions, such as walking, running, normal, common movements in general. Presence of oxygen prevents lactic acid form occurring, which enables these contraction to be performed over a long period. This is especially good for those people who need to reduce some excessive weight. Aerobic or cardio exercises burn a lot of fat since they can be done for a long time. Performing this type of exercises will generally create lean muscles. Other type of workout, anaerobic exercise, is used in situations when fast and highly intensive contraction is needed (when something heavy is lifted, for example). That is why it is obvious that this type of exercising is used in bodybuilding. It cannot be done for a long time because the contraction happens fast and there is simply no time for the oxygen to come into the picture and therefore, lactic acid starts to accumulate and tire the muscle eventually. Therefore, this type of exercise cannot be done for many times, especially if the weight lifted is very heavy.
Skeletal muscles are connected to bones with tendons, while ligaments are used to connect bone with another bone. It is obviously a complex structure, which needs certain things in order to function properly. Muscles need proteins for structure and carbohydrates as the energy source for proper functioning. This is a basic fact, which is used for dieting process. Intake of less carbs as energy source induces fat burning for compensating that lack of energy.