All training is not equal and the intensity to which you approach your training will ultimately determine the results that your body will demonstrate to the public. Training should realistically only take up between 5 and 12 hours a week, at most. Nevertheless, it’s not about the amount of hours you put in but it’s what you put into those hours. You may try to avoid this philosophy by saying to yourself “What if I put in more than 12 hours? Wouldn’t that have the same result?” That couldn’t be farther from the truth. Not only is there the overtraining aspect that we need to carefully monitor (which will create the improper hormonal balance that will put on fat and increase myostatin levels to decrease muscle mass), but the principle of intensity (which we will discuss shortly) dictates what kind of results you will achieve.
Don’t you notice several people that you know who religiously walk miles and miles a day, yet they are far from “in-shape”? I know countless individuals who spend hours exercising, yet they actually walk around with slabs of fat. These individuals burn a ton of calories while exercising, yet their bodies do not develop into a finely tuned machine capable of burning calories long after the exercise is over. Now, have you ever looked at a sprinter? The sprinter exercises for a very short period of time. However, these are short bursts of extremely intense exercise. Even though the former is burning more overall calories during exercise than the latter group, the type of exercise and the trauma presented to your body through the form of intensity is the determinant factor in what dictates the appearance of your physique and your ability to burn fat and build muscle tissue long after the exercise is over.An all-out sprint on the track or set in the weight room under maximal loads is what damages the muscle fibers completely and provides the stimulus for the muscle to gorge itself with blood and ultimately grow back stronger. The reason why this type of training is most effective to your goals is because of the particular type of muscle fibers that it damages. Every muscle group is made up of slow (Type I), intermediate (Type IIa- fast oxidative), and fast twitch (Type IIb- fast glycolytic) muscle fibers. Slow twitch muscle fibers are very efficient at using oxygen to generate more fuel (known as ATP) for continuous, extended muscle contractions over a long period of time before they fatigue. Intermediate fast-twitch muscle fibers can use both aerobic and anaerobic metabolism almost equally to create energy. Fast-twitch muscle fibers get their name by being able to fire rapidly (contracting in under .01 seconds or less after stimulation) and work only under anaerobic conditions. Since they are without oxygen, that means they fatigue very easily.Nonetheless, working these fast twitch muscle fibers in preference to your slow twitch muscle fibers is what will make or break your physique. Slow twitch fibers do not produce any form of muscle growth because in order to activate your slow twitch muscle fibers that means you are working with incredibly submaximal loads. Activating your fast twitch muscle fibers means that your muscles are firing so rapidly because the intensity, or weight, you are working with is near maximal to present hypertrophy. Remember, the more muscle you have, the more fat you burn. That goes for you too ladies.
Moreover, not all muscle fibers are created equal. Slow twitch fibers are about half the diameter of fast twitch muscle fibers and take three times as long to contract. By implementing your fast twitch muscle fibers you are activating a much larger muscle, indicating that it requires much more energy (or calories) in order to activate that muscle, and are working much harder during the actual process since they are firing three times as fast as slow-twitch fibers. It requires an exorbitant amount of energy to allow your fast twitch muscle fibers to respond with such vigor. Moreover, fast twitch muscle fibers hold significantly more glycogen than slow twitch muscle fibers. By breaking down more glycogen, you more easily tap into your fat reserves at a quicker rate than if you were just working your slow twitch fibers. That is why you rarely see a fat athlete who participates in a sport that requires short bursts of energy for 5-10 seconds that require activation of your fast twitch muscle fibers: football, track and field, boxing, basketball, etc.
Intensity is the most efficient way to burn fat not only because of the calories that it burns during exercise though, but also because of the recovery process that takes place after. First off, it takes a lot more energy to recover and repair a larger muscle fiber than a smaller one. More importantly, high intensity exercise elevates your metabolism by around 20% long after the exercise is done. Hormonal changes occur after the exercise that increases fat oxidation following the anaerobic workout. You will have an increased metabolism throughout the rest of the week from this type of central nervous system stimulation. Studies show that oxygen consumption and fat oxidation increases considerably, which requires a lot of energy expenditure to maintain homeostasis. For instance, when comparing individuals performing cardio, studies show that there is a 9x greater decrease in subcutaneous skinfolds (fat) when doing High Intensity Interval Training than traditional endurance based workouts.