Tuesday 5 June 2012

Sports Nutrition: Part 2- Fats


The next part of our story revolves around fats and how athletes may use them to aid their performance. I will be involving trampoline athletes in the majority of my conclusions.  A lot of research has been done of fat metabolism for athletes due to one great assumption. Fat is known to hold more energy per gram then carbohydrates (CHO) or protein (PRO). CHO and PRO only yield 4kcal/gram compared to fat that yields 9kcal/gram. It seems that if fats could be burned instead of glycogen then more energy could be created with the same amount of nutrient. Unfortunately fat is unable to provide energy at high intensities such as 60% of VO2+ (roughly). It seems that the body either does not know how to, or physically can’t metabolize fat at high exercise intensities. The exact physiological reasons are still being investigated.  It seems that all the processes of breaking down fat from the adipose tissue, transporting the fatty acids, reabsorbing them into the cell and mitochondria, beta oxidation and lypolysis takes too long compared to glucose metabolism.
Studies have shown that fat is increasingly used as the duration of the exercise continues. This could be because the body has had time to perform all the necessary processes to have fat available for use. Simply said long duration has a larger effect of fat breakdown. Most people view this as “ yay long and easy exercise” WRONG!!!! Basic energetic will say that you will burn more kcal at higher intensities in a shorter time period then a slow burning of fat for a long time. At the end of the day it is not how much fat, PRO or CHO you burn it is how many Kcal you burn. You will burn many more Kcal at a higher intensity. If you are an athlete that feels a bit heavy or is told they are heavy from their coach, than try High Intensity Interval Training (HIIT). This is a form of training that incorporates a series of interval style exercise bouts of maximum intensity. These usually are about 20-30 minutes due to the fact not many athletes can go at a high intensity for much longer. An example would be 30 seconds of pedalling at 95% of VO2 max and 1 minute of rest x 7 or 8. This has been shown to break down fat at a higher rate than Steady State Exercise (SSE). It has been shown to also increase aerobic and anaerobic capacity and muscle synthesis. SSE is a long and less intense form of exercise in hopes of singling out fat breakdown. HIIT increases fat breakdown because of the energetic spoken of earlier as well as increasing “after-burn”.  After-burn is the common name for Post Exercise Oxygen Consumption or EPOC.

 Figure 1: EPOC is the “sky blue” shaded area where Kcal expenditure is higher than resting levels as the body tries to recover from exercise.

Some people have a belief that EPOC will facilitate a large amount of weight loss however this may not be quite true. It has been shown that low intensity exercise only has a after-burn effect of 7% of the Kcal burned during the session. This means that if you were to burn 500kcal in a work out then only 35 extra Kcal would be burned off. Other studies have shown that after a 1.5 hour work out at about 80% of VO2 max, EPOC Kcal expenditure was about 150Kcal. I do not know about you but I do not know anyone who works out for 1.5 hours and is concerned about after-burn. Lots of different studies have been done and all of them fall between these ranges, usually closer to the former example.  So if you are an athlete, or a normal person for that matter, try HIIT instead of always doing SSE and remember that EPOC is not everything it is cracked up to be. What you do during the training, how often you train and your daily Kcal intake have higher correlations to weight loss rather then EPOC.
                When people increase fats in their diet the body actually gets better at using them by increasing the enzymes such as Hormone-sensative Lipase (HSl) that are used to break down fat. Some people even go as far as saying that extra fat will help lose weight and call this fat loading. Problem is that as soon as you stop taking in fat the enzymes stop being produced as much and you are back to the starting point. Back to the drawing board it looks like.  Some studies have shown that with a fat loading session before exercise that the time to exhaustion was increased for the athlete as well as their Vo2 max. However, some articles showed no increase or showed an actual decrease in RPE. Fat seems to be losing the battle for our trampoline nutrition program. 
It seems that fat is not exactly the greatest supplement for our athletes before or during competition. But maybe it has a place afterwards. A few studies show that dietary fats such as OMEGA-3’s increase creatine-kinase in the muscles. Creatine-kinase is the enzyme that catalyzes the reaction that breaks ATP and creates phosphocreatine. It should be noted that OMEGA-3’s are naturally increased in the body through exercise and may not serve a purpose with extra supplementation.
                A trampolinist will use creatine so perhaps a supplementation of OMEGA-3’s would aid in the energy available from the phosphogen system. This is under the assumption that the phosphogen system would help a trampolinist which is not proven yet considering that the research has not been done, yet.  It seems that CHO has a larger benefit towards a trampolinist than fats due to the fact that fat is used to fuel long duration exercise.  It seems for a single day competition that fat ingestion may not do anything except perhaps for a slight benefit when it comes to post training or post prelim CHO restoration. If CHO’s are mainly used as a fuel source for a  trampolinist after the phosphogen system is used up, then perhaps ingesting fats after a training session in the morning will aid in less CHO being used up to create energy for the next training session.  After a an exercise bout EPOC causes ATP to be burned after the workout and if fat loss is not the goal, which it is not for many high level athletes, then perhaps ingesting fats will take the strain off of CHO and allow fat to fuel the after burn  to a higher degree. DO NOT WASTE CHO, especially if fats can do the job as well.  A study done on cyclists shows this principal well and demonstrated that with an increase of fatty acids in the blood, that there was a decrease in glycogen use. For a trampolinist who wants to save glycogen for the next training, or for individuals three hours after synchro then perhaps a fat load in-between synchro and individual may increase glycogen storage and therefore leave more glycogen for later use in the day instead of the body using up energy in the form of glucose to store glucose. Hopefully you can see how this is counterintuitive.   
                Above I did have a chart from another study performed on cyclists that shows that increasing fat intake during exercise will increase CHO availability. However, most likely for copyright purposes, my computer will not allow me to post it on my wall. Please go to this link and scroll to figure 4. It shows how CHO is spared with an increase in fat intake. (LINK: http://www.jappl.org/content/91/1/115.full) This study basically proves that CHO sparing does indeed work, at least for cyclists. Maybe there is a place for it during strenuous competitions or training multiple times in a day. As I said before I am going to look into trying to prove this with Canadian Sports Center, so please be patient as I try to set up a study on trampolinists to determine of any of these “text book theories” truly apply to trampoline.
                So in conclusion fat ingestion pre,during or post workout will not increase performance for a trampoline due to the fact that trampoline does not require energy in this form. Fat fuels exercise for long durations rather than short power bursts. Fat may increase CHO availability in a second training session during the day or a second competition during the day by taking the load off of CHO to replenish stores after the first workout or competition. The relative benefits of this may be small however due to the fact CHO supplementation only really helps exercise bouts over 1 hour, but I am currently trying to give everyone an actual statistical number soon with the help of Canadian Sports Center. So far it seems that neither Cho or fats are causing a huge improvement to trampolinists except for post workout replenishment, but perhaps something about protein ingestion may be our missing puzzle piece. Keep a look out for the  last series of these nutritional articles for a conclusion. ThanksJ

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