Tag Archives: Fasted cardio

HIIT, fat loss and muscle!

High intensity interval training (HIIT) is a very popular training method. When used correctly it effectively improves cardiovascular conditioning, burns fat and promotes new muscle growth. In addition a relatively short HIIT session is sufficient to elicit substantial performance gains. Like any training method, understanding the basic physiological principles will make a big help to using it effectively. This article will explain a bit about this type of training and some of the pitfalls to watch out for.

HIIT is popular because it is time effective. An individual can burn a lot of calories in a short space of time. As the name implies it is an intense form of exercise. Our energy systems function on a simple mechanism of energy charge. The rate of energy (Adenosine Triphosphate/ATP) utilization in the muscle cell must be matched by an energy supply system. Slow rate of energy expenditure during low intensity work is supported by oxidation. Oxidation supplies a lot of energy but at a slow rate. High intensity work is supplied by the glycolysis and phosphate systems which have a much faster supply. Supply must meet the demand. There is often a slight lag between utilization and supply. This means that even during rest intervals and post exercise energy consumption is still elevated. In simple terms our metabolism is increased and we continue to burn more calories than at normal rest conditions. For this reason even though a 20min session burns, for example 500kcals, energy expenditure is raised throughout the day. A low intensity session lasting one hour may burn 800kcal with minimal elevation in metabolisms for the rest of the day. For this reason HIIT may actually burn more calories on a daily basis. This is why it is so effective at fat burning.

HIIT can also be performed with a strength endurance element, supporting a leaner physique!

HIIT can also be performed with a strength endurance element, supporting a leaner physique!

In addition, the power output which is produced during the work period of HIIT is high. Higher power output during work periods are often effective in improving your conditioning. It also helps maintain strength and power simply by utilizing larger motor units. The main issue to consider with HIIT relates to energy supply. If we cannot supply the cells with adequate energy then they become damaged. This is known as metabolic stress. A certain degree of metabolic stress or damage can be reversed. This is what promotes new muscle growth. Moderate metabolic stress during training can, at times, be quite effective for promoting hypertrophy.

If we place too much stress on the muscle cells the damage can be irreparable. The cells will begin to die. When this happens on a regular basis muscle wastage can occur. It also places the body under larger amounts of general stress which will begin to impact on our immune system. There is a large list of potential health implications that this can eventually lead to.

Preventing this scenario is relatively easy but not always something we think about. One of the determinants to energy supply is our energy store. In the case of HIIT we need adequate stores of glycogen for an adequate supply of energy. If we do HIIT in a fasted state we are putting ourselves under severe metabolic stress, as there is little energy supply to fuel it. In addition the lack of energy will dramatically reduce performance so conditioning benefits may also be lost.

The take home message is this. Fuel up for intense exercise! Low intensity exercise can be done in a fasted state as the oxidative system works effectively to provide fuel. With intense exercise such as HIIT style training, you must have some glycogen stores or glucose in the bloodstream. If you are in a totally fasted, glycogen depleted state then consume some simple sugars close to training. By doing so you can maintain high intensity and reduce cell stress. You will still achieve an elevated metabolism that promotes fat burning. You also place the cells under just enough stress to help promote hypertrophy

It is important to understand training methods as the smallest oversight can cause more harm than good. HIIT is an effective tool but if it is not adequately fuelled it loses a lot of its benefits. It is a popular successful way to train and should be used in any program. Like any training method the process is the important part. It needs to be considered and managed properly in order to see the full benefit.

Fat loss for athletes!

Body composition and body mass are important for most sports. The success of an athlete can rely heavily on falling within the norms of their sports, especially where a weight category is involved. Nutrition and training are both vital in the role body composition and weight management. I will not discuss dietary strategy as it is not my are of expertise. Instead I will discuss the training considerations and strategy.

Step one is for an athlete to identify whether he needs to reduce bodymass (weight) or reduce body fat. Bodymass deals directly with bodyweight on the weighing scale with no concern for body composition. Body fat deals with body composition with possibly no influence on overall bodymass. When reducing body mass the main focus, is to create a consistent calorie deficit. How one trains doesn’t really matter as bodymass will decrease over time if calorie expenditure exceeds consumption. The issue is that this reduction will not be selective in terms of tissue loss. Both muscle and fat tissue will be lost but this is not such a good thing. In many cases an athlete will need to retain as much lean mass as possible and may even need to increase or at least maintain it. This creates a more complicated scenario where fat tissue must be the focus for reduction while avoiding any muscle tissue loss. The training strategy becomes a little more complex.

We know that in terms of metabolism, exercise at lower intensities utilise fat as fuel more effectively than high intensity exercise. The main drawback is that in terms of time efficiency it takes a relatively long period to burn sufficient calories. The other issue is that low intensity work can promote adaptations that are not so favourable for an athlete. Long periods of low intensity (LSD) training can promote a conversion of type 2 muscle fibers into fibres which more resemble the characteristics of type 1 muscle fibers. The athlete runs the risk of losing strength, speed and power. So this method must be used sparingly.

High intensity training has been touted as the magic pill for fat loss and performance in recent literature. Calorie expenditure is higher for a given work period and metabolism is elevated in the post training period. Sessions must, however be shorter as they will be more demanding. It is in this post training period where an elevated metabolism and active oxidative system plays its role in metabolising fatty acids. HIT may also promote strength, power and conditioning through a number of adaptive responses. At first glance this seems to be the obvious choice. As with most training methods it carries its disadvantages. By focusing on HIT we become reliant on the Glycolytic system during exercise. This system utilises carbohydrate metabolism and is always active even at rest when the oxidative system is dominant. Over time an athlete may promote the use of carbohydrates during metabolism which will in fact spare fat cells. If they do not consume enough carbohydrates there can also be a reduction in lean tissue as muscle cells do not get enough energy to survive.

The best strategy is to utilise both methods in an appropriate fashion. LSD can be made more effective in reducing fat and improving fat oxidisation by adding fasted LSD sessions into a program. Done before breakfast or immediately following a training session, enzymes active in fat oxidation must up-regulate to compensate for glycogen depletion. This means that less time is needed to initiate fat oxidation. HIT should then be performed in a fuelled state in a separate session to make use of its benefits. When both types of sessions are used in a balanced way that does not impede the athletes recovery, they can see all the benefits while negating the disadvantages.

As with most strategies a balance is required for optimum results. The body is exceptional at adapting to stress. Overemphasising one method over another will only display short lived success and may create problems in the long run. In the case of managing body weight and body mass a strategy must be formulated to suit the needs of the individual. A gradual and monitored approach is best for achieving long term and consistent results.