| Over the weekend, a really good friend was | | | | What Does It All Mean? |
| discussing how he "just can't seem to lose 2 kilos". He | | | | In order to burn more fat, the intensity level must be |
| feels that it is fat weight and we discussed ways in | | | | kept at a level that is sustainable for long enough to |
| which he can change his workout to optimize fat loss. | | | | move into the "fat burning zone" or Oxidative System. |
| This got me started thinking about how many different | | | | Most people have about 2 hours of stored glycogen |
| methods of fat loss and fads have come and gone | | | | (glucose) in the muscle when exercising at moderate |
| over the many years that I have been a fitness | | | | intensity. So it's safe to assume that unless you are |
| instructor. | | | | running a marathon, you are using both stored glucose |
| If there is one thing I have learned - exercising regularly | | | | and fat when doing your aerobic training. This applies |
| over time will work to burn fat. The methods that work | | | | to whatever type of aerobic training you |
| for each individual vary depending on the individual's | | | | choose.Weight training, on the other hand, relies on |
| weight, cardiovascular fitness level, activity level, | | | | stored available carbohydrate (glucose) because the |
| metabolism, muscle development, size and even | | | | short duration/high intensity of each lift doesn't call for |
| gender! | | | | the body to burn fat for fuel. |
| For all of us, though, if we eat more than our body | | | | The argument that low intensity long duration exercise |
| requires - we either store it as fat or have to "burn it | | | | burns a greater percentage of calories from fat still |
| off". | | | | stands. Example: a comparison of the calories |
| The body at rest uses energy (calories) to power the | | | | expended by the same person walking for 1 hour and |
| organs, brain, cardiovascular system, immune system | | | | jogging for 1 hour reveals that the walking burns a |
| and skeletal muscle. In other words, all of the cells of | | | | much greater percentage of calories from fat although |
| the body require energy. The rate in which the body | | | | the overall calorie expenditure is lower. |
| uses energy to function is known as the basal | | | | In terms of just pure calorie consumption during |
| metabolic rate. There are two other areas of calorie | | | | exercise - the more oxygen you use the greater your |
| requirements, one known as the thermic effect of | | | | calorie use. If we look at the Oxidative System which |
| eating (energy required to digest food) and the thermic | | | | uses fat, but requires more oxygen to do, we can infer |
| effect of exercise. | | | | that working out at medium intensity for longer |
| So how does the body convert energy for use during | | | | durations will burn more calories AND a higher |
| exercise? There are 3 principle metabolic pathways, | | | | percentage of fat. |
| which are the ways in which the body produces | | | | The current thinking is that the more muscle groups |
| Adenosine Triphosphate (ATP). I promise not to go too | | | | engaged during the activity (example: aerobic dance |
| technical here and risk boring you... | | | | with arms and legs), the harder the body works |
| 1. The ATP-PCr System | | | | requiring more oxygen and more calories. Do it long |
| This is used during the first few seconds of exercise. | | | | enough, the body will burn a higher percentage of fat. |
| Creatine phosphate (PCr) in the blood is used to | | | | There's a lot of discussion about the "afterburn" or the |
| produce ATP which powers the cells. | | | | thermic effect of exercise recovery. Yes, the body |
| 2. The Glycolytic System | | | | does burn energy to recover. A more intense workout |
| Glycolysis means the breakdown of glucose. The | | | | requires more energy to recover - hence more |
| body uses this system for the first few minutes of | | | | calories burned after the workout. |
| exercise. If the exercise is very intense (say sprinting), | | | | There are many fitness programs that advocate |
| glucose in the blood is used without oxygen and the by | | | | interval aerobics for fat burning. There are just as |
| product of this will be lactic acid. After a while, the | | | | many that advocate long duration aerobics for fat |
| lactic acid accumulates (the burning sensation in the | | | | burning. I advocate a combination of the 2. Both will |
| muscle) and leads to muscle failure. This is known as | | | | burn fat. Each has benefits beyond fat burning. |
| anaerobic or fast glycolysis. If the exercise is less | | | | Interval training increases your cardiovascular strength, |
| intense (jogging), glucose in the blood is used with | | | | output, heart rate recovery and produces a stronger |
| oxygen to produce ATP and the by product will be | | | | "afterburn". |
| pyruvate which then is used by the oxidative system | | | | Long duration trains the cardiovascular system to |
| below. This is known as aerobic or slow glycolysis. | | | | sustain an increased load for a longer period of time |
| 3. The Oxidative System | | | | and teaches the body to convert fat to energy more |
| This system is has 4 parts which I definitely won't go | | | | efficiently for use during exercise (endurance). |
| into except to give you the names: slow glycolysis | | | | Whatever aerobic activity a person does, the key is to |
| (discussed above), the Krebs Cycle, Electron | | | | keep doing it. Why? The more a person exercises, the |
| Transport Chain and Beta Oxidation It is in this system, | | | | more efficient the body becomes at converting and |
| fats more than carbohydrates (glucose) are used to | | | | using available carbohydrate and fat. So... regular |
| generate ATP. This process is called lipolysis. The fat | | | | aerobic exercise over a long period of time is more |
| produces more "energy" (ATP molecules), but also | | | | important for fat and calorie burning than which |
| requires more oxygen. | | | | method used. |