Using exercise as part of your weight loss strategy, is always strongly recommended, and as long the nutritional component of the equation is correctly addressed, there should be no reason why a reduction in mass should not follow.

However, there are certain misconceptions and beliefs that one method of exercising to accelerate weight loss is superior to the other.

Professionals have advocated two approaches to training: the high intensity approach - just burn as many calories as possible, and the "slower is better" approach, that had us spending hours and hours exercising at a low intensity to shed the fat.

The one common denominator in all the approaches is the phrase Training Intensity.

Without going into to much detail, training intensity is basically how hard you are exercising.

So how do you know how hard you are pushing yourself? Am I pushing myself hard enough, or should I back off the Intensity just a bit?

These questions can be answered using one of these 2 approaches:

Heart rate monitor (HR monitor) - a device that quantifies how hard you are pushing your body, by getting a real time reading from your heart (in beats per minute). The higher the heart rate, the harder you are exerting yourself.

Rating of Perceived Exertion (RPE) scale - this scale uses each individuals perception of how hard they are exerting themselves, to quantify their training intensity.

And as you might have noticed, the harder you push yourself, the more calories you expend - which is a good thing, right?

Not always.

You see, the intensity at which you train, will pull energy from different energy pathways that the body has developed to meet the requirements placed on it.

For example, there is a pathway that allows us run a marathon. Another pathway allows us to pull ourselves up and over a wall, while yet another pathway allows us to lift weights.

Each one of these pathways produces energy in a different way, and gets the fuel needed to produce that energy from a different energy molecule (substrate).

Fat is the most energy dense molecule available, and is generally available in fairly large quantities. However, it is not the bodies first pick because it is a very difficult molecule to withdraw energy from.

Carbohydrates on the other hand,are the bodies preferred energy source Unfortunately, we only have about 60 minutes worth of Carbohydrate energy stored (Glycogen is the term for stored Carbs) in the muscle and the liver.

So you might be wondering where this talk about intensity and energy substrates is going?

Well, fat requires the following circumstances to be most effectively pulled and used for energy:
  1. A good supply of Oxygen that can take part in the reaction needed to remove the energy from the fat molecule.
  2. Very little Lactic Acid in the body, as this shuts down the Lipolytic process (Fat burning).
It is that simple.

To meet #1, we need to ensure the breathing rate is not elevated to the point that you feel like you are gasping for air. This will ensure each breath fills the lungs completely, and there is sufficient Oxygen diffused into the blood stream, and whisked off to the muscle.

To meet the requirements of #2, the training Intensity must be kept under control.

Work at a heart rate intensity of about 55% - 65% of you Maximum Heart rate(HRmax)

Please check out our FREE Heart Rate monitor video resource for more information on Heart rate monitors, using them and setting them up.

This Polar Heart Rate prediction chart will help you better understand the Training zone concept.

If you are using the Rating of Rating of Perceived Exertion scale, then working at a rating of between 9 & 13, will correlate very closely to 55% - 65% of HRmax.

If your intensity is higher, your body will reduce the amount of fat it metabolizes and increase the amount of Carbs it burns. The reason for this change is that as training intensity increases, the body requires energy to be delivered more rapidly and in larger quantities.

The Fat burning system (Lipolytic pathway), cannot meet this demand, so the reliance on Carbohydrates increases, and you Caloric expenditure shifts.

However you choose to workout, it's important to remember that exercise contributes to our overall sense of well being, and our vigor and mobility later in life.

But always keep this in the forefront of your mind: when it comes to weight loss, what you put into your mouth, and when it goes in, really forms the basis of your weight loss success.

James Greenwood is a competitive tri and multisport athlete currently training for Ironman Canada 2009. A level 1 Triathlon Coach, he holds a post graduate degree in Exercise Science, and is a Certified Strength and Conditioning Specialist through the NSCA. James is also currently the resident health and fitness programs expert at, and has starred in a number of multisport specific fitness videos.
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