At the end of this post, you will find one of the many research articles on Interval Training and why it is the best method of exercise for weight loss and fitness.
There is strong evidence that interval training is highly effective to dramatically improve your fitness level and muscle tone, as well as burning fat while maintaining muscle mass. Plus, the fat burning continues after interval training throughout the rest of the day.
There are many many such articles and research studies that support these claims.
So the scientific research can satisfy participants that EET workouts are the most effective possible.
But, there is more to the story. EET included the interval workouts before reading very much scientific research at all.
Why else would interval workouts be part of EET?
The answer lies in the fundamental concepts behind the EET Fitness Plan. Survival Instinct and sending the most powerful messages to your metabolism possible in order to create a new metabolic memory, which assists participants in losing weight and becoming more fit. Here's how it works:
Assume you lived in the time of the Ancient Romans and that you were a slave who was forced to become a gladiator.
During your fights, you would push yourself physically as hard as you could for a relatively short time (until you killed your opponent or they killed you). Even within each fight you would have times of maximum exertion wrestling your opponent, and a few brief pauses when you could try to catch your breath.
And, each time you would be asked to fight, you would know that your life depended on it. Your upcoming fight would be on your mind far more than when you were just fighting, and your body would be aware that it was going to be asked to defend itself to the highest level possible far more often than just during your fights.
The gladiators workout regime has several similarities to an EET Fitness Participant. First, by pushing yourself as hard as you can you are sending a clear message to your body/metabolism that you must be CAPABLE of doing your workout at the highest level of intensity you can manage, and your body/metabolism must adjust so that you can perform and continue to succeed at your workouts. Your body/metabolism will begin to do what it takes to become lighter and leaner to make it easier to survive the intensity of your interval workouts.
The message is just as clear that your body needs to retain as much muscle as possible in order to perform the challenging intervals. Also, by taking short breaks between sets of your intervals, you are sending a clear message to your body that you will allow your muscles to recover so you have full access to them during your sets.
Everything about the interval workout sends the ideal message to your body/metabolism and your mind about how you want your body to look and the level of fitness you desire.
Secondly, your body/metabolism as well as your mind will be aware at all times that the next interval workout is coming soon (within 24-48 hours) and therefore must continue to prepare itself to be able to handle that workout, in order to "survive".
This is why the workouts don't have to be long in order to have dramatic results. If your body knows it will be pushed to your limits even for a short time, it must be prepared to handle it and therefore it will work all day to ensure you are prepared for your battle.
As you continue to repeat and improve at EET's Fat Burning Workouts, your body and metabolism will understand the powerful message you are sending, that you are asking it to do something different than it has before, and as a result, your body and your metabolism must change in accordance with the message being sent.
And, like the gladiator, your body/metabolism will ensure throughout the day that you are prepared to handle your next brief "test of survival". Repetition of interval workouts will become a key part of your new metabolic memory that your body needs to be lean and fit because intervals will be an ongoing part of your life.
HIGH-INTENSITY INTERVAL TRAINING:
THE OPTIMAL PROTOCOL FOR FAT LOSS?
As exercise intensity increases, the proportion of fat utilized as an energy substrate decreases, while the proportion of carbohydrates utilized increases (5). The rate of fatty acid mobilization from adipose tissue also declines with increasing exercise intensity (5). This had led to the common recommendation that low- to moderate-intensity, long duration endurance exercise is the most beneficial for fat loss (15). However, this belief does not take into consideration what happens during the post-exercise recovery period; total daily energy expenditure is more important for fat loss than the predominant fuel utilized during exercise (5). This is supported by research showing no significant difference in body fat loss between high-intensity and low-intensity submaximal, continuous exercise when total energy expenditure per exercise session is equated (2,7,9). Research by Hickson et al (11) further supports the notion that the predominant fuel substrate used during exercise does not play a role in fat loss; rats engaged in a high-intensity sprint training protocol achieved significant reductions in body fat, despite the fact that sprint training relies almost completely on carbohydrates as a fuel source.
Some research suggests that high-intensity exercise is more beneficial for fat loss than low- and moderate-intensity exercise (3,18,23,24). Pacheco-Sanchez et al (18) found a more pronounced fat loss in rats that exercised at a high intensity as compared to rats that exercised at a low intensity, despite both groups performing an equivalent amount of work. Bryner et al (3) found a significant loss in body fat in a group that exercised at a high intensity of 80-90% of maximum heart rate, while no significant change in body fat was found in the lower intensity group which exercised at 60-70% of maximum heart rate; no significant difference in total work existed between groups. An epidemiological study (24) found that individuals who regularly engaged in high-intensity exercise had lower skinfold thicknesses and waist-to-hip ratios (WHRs) than individuals who participated in exercise of lower intensities. After a covariance analysis was performed to remove the effect of total energy expenditure on skinfolds and WHRs, a significant difference remained between people who performed high-intensity exercise and people who performed lower-intensity exercise.
Tremblay et al (23) performed the most notable study which demonstrates that high-intensity exercise, specifically intermittent, supramaximal exercise, is the most optimal for fat loss. Subjects engaged in either an endurance training (ET) program for 20 weeks or a high-intensity intermittent-training (HIIT) program for 15 weeks. The mean estimated energy cost of the ET protocol was 120.4 MJ, while the mean estimated energy cost of the HIIT protocol was 57.9 MJ. The decrease in six subcutaneous skinfolds tended to be greater in the HIIT group than the ET group, despite the dramatically lower energy cost of training. When expressed on a per MJ basis, the HIIT group's reduction in skinfolds was nine times greater than the ET group.
A number of explanations exist for the greater amounts of fat loss achieved by HIIT. First, a large body of evidence shows that high-intensity protocols, notably intermittent protocols, result in significantly greater post-exercise energy expenditure and fat utilization than low- or moderate-intensity protocols (1,4,8,14,19,21,25). Other research has found significantly elevated blood free-fatty-acid (FFA) concentrations or increased utilization of fat during recovery from resistance training (which is a form of HIIT) (16,17). Rasmussen et al (20) found higher exercise intensity resulted in greater acetyl-CoA carboxylase (ACC) inactivation, which would result in greater FFA oxidation after exercise since ACC is an inhibitor of FFA oxidation. Tremblay et al (23) found HIIT to significantly increase muscle 3-hydroxyacyl coenzyme A dehydrogenase activity (a marker of the activity of b oxidation) over ET. Finally, a number of studies have found high-intensity exercise to suppress appetite more than lower intensities (6,12,13,22) and reduce saturated fat intake (3).
Overall, the evidence suggests that HIIT is the most efficient method for achieving fat loss. However, HIIT carries a greater risk of injury and is physically and psychologically demanding (10), making low- and moderate-intensity, continuous exercise the best choice for individuals that are unmotivated or contraindicated for high-intensity exercise.
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