One of the most common questions that I am asked by clients is "what should my heart rate be to stay in the fat burning zone?" This question is making cardiovascular exercise more complicated than it needs to be.
Firstly, here is a little background information. Carbohydrates, fats and proteins are macronutrients. They provide our bodies with the fuel that can be converted to the energy that we need in day to day activities and exercise.
Carbohydrates can be simple "carbs" (such as sucrose, lactose, fructose and maltose) or complex carbs (starch, fibre and glycogen). Carbs tend to be the body's preferred energy source, especially during moderate to high intensity exericse.
Proteins are made of amino acids. They play many important roles in the body:
- required for the structure and function of cells,
- building muscle,
- making antibodies, enzymes etc..
When we have a shortage of carbohydrates and fat in the body, protein can also be used as an energy source.
Fats are an essential part of our diet, being used in physiological processes and also providing an energy source. The different types of fat are:
- Saturated fats (these increase our "bad" cholesterol and increase the risk of heart disease)
- Polyunsaturated fats (such as omega 3 and omega 6 fatty acids)
- Monounsaturated fats (plant based eg olive oil).
Now to cardiovascular training. This is the type of exercise that increases your heart rate and breathing rate. Examples include swimming, running and cycling. It improves your overall health and fitness, including the efficiency of your heart and lungs.
In the past, it has always been said that lower intensities of cardiovascular exercise burn a HIGHER PERCENTAGE of stored fat, leading to the term "fat burning zone". The problem with staying within this fat burning zone is that you will also burn calories more slowly (LESS CALORIES).
Here's an example:
You walk at 7km/hr for 30 minutes, keeping your heart rate in the "fat burning zone" of 60-65% of your maximum heart rate. You burn 145 calories with 50% of these calories coming from fat, that equals 72.5 calories of fat being used.
You alternate jogging at 10km/hr and walking for 30 minutes, with your heart rate in the range of 80% of max heart rate. You burn 205 calories and nearly 40% of these come from fat. This equates to 82 calories of fat.
From this you can see that it is best to keep it simple! Aim to burn as many calories as you can in the time that you have. By working a little harder, you will burn more calories and also increase your heart and lung capacity which leads to a fitter you!