Category Archives: Nutrition

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.

Carbs and competition.

First off, I am not a dietician, nutritionist or even self proclaimed food guru. There are plenty of folk out there willing to preach about what you should and should not eat but that’s not my area. I am purely going to focus on the role of carbohydrate in sporting performance. Quite recently there has been large debate over carbohydrate in our diets. The “Health and Fitness revolution” has given rise to an enormous amount of conflicting information. People very easily fall for the latest fitness trends in search of the magic pill! The role of carbohydrate in human performance is pretty simple, it is fuel! Lately we have seen a large amount of athletes at the performance lab attempting to eat paleo. While I don’t have an issue with the paleo concept we have noticed that their diet, while rich in fruit and vegetables, is still generally quite low in carbohydrate as a nutrient. Paleo foods tend not to be very carb dense in comparison to other sources which they have now eliminated from their diet. As a result their performance tends to suffer somewhat. Dr. Loren Cordain one of the founders of the paleo diet concept also states this concern quite clearly in his work. We go to great lengths, explaining to athletes why carbohydrates are so important in their diet. That will be the focus of this post.

The Science

As most of you are aware the body uses three main energy systems. Glycolysis is the system which deals with carbohydrate as it uses glucose to generate ATP. At low intensity exercise the oxidative (Aerobic) system is most active. At increasing intensity larger motor units become active. These motor units tend to be glycolytic in nature (Anaerobic). These consume glucose which is sourced either from the bloodstream or stores known as glycogen. Once glucose and glycogen stores are depleted higher intensity cannot be maintained. This translates to a reduction in power output and speed. It is therefore important that an athlete has an adequate amount of glycogen stored prior to competition to maintain performance. Athletes will try to develop their oxidative system in an attempt to preserve glycolytic fuel stores. Fat stores contain more energy. The longer they can run on fat for energy the less glycogen they will use. The mistake people make is in thinking there is a distinct switch between fuels and energy systems. This is not the case. At all times all three systems are active but one will be more dominant. For this reason all systems must be considered in terms of diet and training. The nature of their sport will influence the nature of an athletes metabolism.

Game sports

rugby world cup 2011 NEW ZEALAND ARGENTINA

Image: rugby world cup 2011 NEW ZEALAND ARGENTINA by Jeanfrancois Beausejour

The level of intensity varies greatly in team sports. Depending on position there can be an extremely varied utilisation of one energy system or another. Glycolysis is however generally very active throughout game scenarios in team sports. Numerous studies have examined carbohydrate supplementation during a games. The supplementation groups showed a better maintenance of speeds and a greater distance covered in the later stages of a game than the non supplementation groups. In addition to this other studies have shown in soccer that better performing teams cover larger distances per game than poorer performing teams of the same league. It is pretty clear that carbohydrate is quite an important factor in performance.

Endurance sports

Photo Chris McCormack https://creativecommons.org/licenses/by-nd/2.0/

Photo Chris McCormack
https://creativecommons.org/licenses/by-nd/2.0/

Endurance sports are a little more interesting as the success of an endurance athlete is heavily related to fuel management and efficiency. A successful endurance athlete will dedicate a large amount of training time aimed at increasing oxidative capacity. This allows them to stay aerobic for longer essentially preserving glycogen. They aim to be as effective as possible at utilising fat metabolism. This will allow them to save glycogen for periods where they need to call on larger motor units. In short they try to use glycolysis only when they need to maintain a higher pace. The length of their event will determine the pace they wish to maintain and therefore the reliance on glycolysis and carbohydrate as a fuel source.

I will not mention individual foods or diets as I think that is mostly down to individual preference. The point I want to stress is that carbohydrate plays a very important role in performance for nearly all sports. It is important for an athlete to understand that role and not neglect it. They must choose a nutritional strategy that best suits the requirements of their given sport. At the end of the day their performance will reflect wether their diet is good for them or not!