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Interval training: The secret to super-conditioning and extreme fat loss! 

There are a lot of frustrated people out there. Lots of people exercising several times a week, who never seem to lose much weight or make any real progress. A lot of the time, it’s those who spend 45 minutes a couple of times a week on the treadmill, elliptical trainer or exercise bike, with no real plan or purpose. They get frustrated, wondering how it is that they spend several hours a week exercising, yet get very few results.

Don’t get me wrong, this type of exercise is good for your overall cardiovascular health, but it’s not the most effective way to shed bodyfat.

To understand why this type of exercise yields few results, requires a bit of an explanation about the energy pathways and metabolism involved, and how your body works and uses energy.

All the energy your body requires, for muscle contractions, organ function, literally everything, comes from a molecule called Adenosine Tri-phosphate (ATP). When this molecule is broken down, energy is released. 

The energy released, is what drives all processes in your body. Your body’s energy production revolves around rebuilding the ATP molecule.

How your body produces ATP depends on a multitude of factors, but one of the key factors, especially when concerned with exercise, is the intensity of the  physical activity being performed, because the ATP pathway and the type of activity you are engaged in play a major role in your ultimate fat loss goals.

Physical activities can be classified into four basic groups, based on the energy systems that are used to support these activities. 

  1. Strength-Power: Energy comes from immediate ATP stores. Shot put, power lift, high jump, golf swing, tennis serve, or a throw;  0 to 3 seconds of maximum effort. 

  2. Sustained-Power: Energy coming from immediate ATP and CP stores. Sprints, fast breaks, football lineman; 0 to 10 seconds of near maximum effort.
     
  3. Anaerobic Power-Endurance: Energy coming from ATP, CP, and lactic acid. 200- to 400-meter dash, 100-yard swim; lasting about 1 to 2 minutes.

  4. Aerobic-Endurance: Energy coming from the oxidative pathway. Events lasting over 2 minutes in duration. 

What you need to understand is that Activities 1-3 are all anaerobic activies, meaning they make use of your anaerobic (absence of oxygen) metabolism to create energy, whilst Activity 4 makes use of your aerobic (in the presence of oxygen) metabolism to produce energy.

Without going into too much detail, what you need to remember is that for all anaerobic activities, energy (ATP) is produced from carbohydrates.

For aerobic activities, a totally different process is used to produce energy and although, more energy is released, it takes longer for this energy to be released. 

The process is known as the oxidative pathway. Another process known as Beta-oxidation also involved. In Beta oxidation, fatty acids are broken down to ultimately produce energy. 

Beta oxidation does not occur at activities of high intensity, only during  low-intensity, sustained activities. It is estimated that at rest 70% of energy comes from fat via Beta oxidation, whilst at super-high intensity activity, almost 100% of energy comes from carbohydrates.

So, essentially the crux of the issue is that for any activity which you cannot sustain for 2 minutes or more, you are using carbohydrates as your primary fuel source, and for activities you can sustain for longer periods, you will be using fat as a fuel source, as well as some carbohydrates.

What is difficult for many people to understand is that you actually burn more fat in the long run, by not using fat as your main fuel source during exercise (i.e. by doing long, low intensity cardio sessions). I know it seems completely counter-intuitive, but let me explain:

When you ingest carbohydrates your body breaks them down into glucose and it enters your bloodstream, when your blood glucose levels go above a certain-point, your body will convert it into glycogen by joining many glucose molecules together. The glycogen is then stored in your muscles and liver. Your muscles and liver can only hold a certain amount of glycogen, so any excess is stored as fat.

So, if you are only doing low-intensity cardio, you will primarily be burning fatty acids, not glucose and glycogen. So, even though you do burn many calories when you are exercising, because your glucose and glycogen levels have not been depleted, the next time you eat, any excess carbohydrates will still be stored as fat.

But, if you do exercise which is of a higher intensity, you will be depleting your glycogen stores and then the next time you eat, and possibly even for several meals after your workout, all of that glucose from the carbohydrates you ingest will go to replenishing your glycogen stores, not stored as fat.

So how should you be exercising then?

Well as you can now see, what is important is that you burn fat, but it’s also important that you train in such a way so as to prevent yourself from storing any new fat. 

The answer is interval training.

Interval training is where you cycle the intensity of effort. 20 minutes of interval training will be far more effective than 45 minutes low-intensity work on the treadmill.

With interval training, what you are doing is making your body utilize many of the different fuel sources, using fat as a fuel source part of the time and then using almost exclusively carbohydrates as a fuel source at other times. This is achieved by doing some low-intensity work for a couple of minutes, some medium-high intensity work for a couple of minutes and then maybe 1 or 2 minutes of all-out maximum effort, then followed again by some low intensity effort, again working up to another round of maximum effort, repeated a couple of times. Apart from utilizing multiple fuel sources and curbing the storage of new fat, this type of training also induces other metabolic changes and have you burning fat even after you have finished working out (due to the more taxing recovery process). 

Many different activities can be performed in an interval training session, you don’t have to perform only one type of activity. You could alternate between a rowing machine, an exercise bike or a treadmill for example, do low-intensity on one and then high intensity on another. You could even incorporate bodyweight exercises or free weight exercises into an interval training session.

For example, you could run on the treadmill or row for the low-intensity rounds and then do kettlebell swings for a minute at your maximum capacity for the high-intensity rounds. The possibilities are endless and it pays to get creative sometimes, as you are likely to get bored doing the same workout over and over. 

The main thing to remember is that your total workout time adds up to AT LEAST 20 minutes and that you have several rounds of high intensity, maximum effort for 30 seconds to 1 minute, followed by lower and medium intensity effort for a few minutes. Do this 3 to 4 times per week depending on your other activities 
(sports, weight training routine etc).

What are some good examples of interval training?

Example 1:

This one is taken from Bill Phillips’ Body for Life program, I have found it very effective and it can be performed using most activities (rowing, swimming, running, cycling etc.)

The session lasts 20 minutes, with the intensity peaking right at the end. It works on an percieved intensity scale of 1 – 10, with 1 being extremely easy, requiring almost no effort at all, and 10 being your absolute maximum effort.

During the first 2 minutes, intensity should be at level 5. Minutes 3, 4, 5, and 6 should be at intensity levels 6, 7, 8, and 9 respectively. Minute 7 goes back down to intensity level 6 and then continues in this pattern until the 19th minute where you push intensity level to 10. The last minute is a cool-down to level 5 intensity. 

You should be completely exhausted at this point so make sure to stretch afterwards.

Example 2:

Below is another one I like to use from time to time, its extremely tough, but really works.

3 minutes of rowing at intensity level 6 (warm up)
1 minute of rowing at intensity level 8
1 minute rowing at intensity level 5
1 minute rowing at intensity level 6
1 minute rowing at intensity level 9
1 minute rowing at intensity level 5
1 minute burpees (with push-up)
1 minute kettlebell swings

Rest 30 seconds

2 minute rowing at intensity level 6
1 minute rowing at intensity level 9

Rest 2 – 3 minutes and then repeat (without warm up).

So if you're looking to shed that fat and improve your conditioning massively, it's time you started some interval training.

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