<<Previous Page

How much and how often should I perform cardiovascular exercises for fat burning?

For cardiovascular fitness, the Health Education Authority recommends 20 minutes of high-intensity aerobic activity
repeated three times a week. As this level of training can only be
managed by very well­conditioned athletes, an alternative recommendation
of 30 minutes of moderate intensity activity repeated five times a week
would be suitable for beginners and intermediate fitness participants.

Should I use High or Low-Intensity Cardio Exercise for Fat Burning?

Whether you choose a high or low-intensity cardio program for fat
burning depends on your goals, fitness level and time available. Both
types will develop cardiovascular fitness and bum fat but high-intensity
cardio (over 70% of your V02 max)
is more effective. If time is a premium, shorter periods of
high-intensity cardio will give you the same results in terms of fat
loss as longer periods of low-intensity cardio.

Is Low-Intensity Cardio Exercise best for Fat Burning?

It's been a long-held belief that low-intensity cardio is the best
way to burn fat. While this may be appropriate for beginners and is
certainly more attractive for many casual exercisers, serious fitness
trainers and athletes will reap greater benefits from training at a
higher intensity. In fact, it is a myth that training in the so called
'fat-burning zone' (around 60-70% MHR) is optimal for fat burning.

The theory about the fat-burning zone came from a study that showed
that low­intensity exercise burns a greater percentage of calories from
fat than from carbohydrate. When high-intensity exercise is practiced,
the percentage of fuel from carbohydrate is increased. However, the
amount of fat burned is greater than or equal to that burned during
low-intensity exercise. When it comes to fat loss it is not the
proportion of each fuel metabolized but the total calorie expenditure that
is most important. For the same workout time, you will burn more
calories and more fat with high-intensity cardio. For example, walking
(low-intensity cardio) for 60 minutes will burn about 270 kcal, of which
approximately 60% (160 kcal) come from fat, while jogging
(high-intensity cardio) for 60 minutes will burn about 680 kcal, of
which approximately 40% (270 kcal) come from fat. Thus, the higher
intensity exercise results in a greater fat loss over the same workout
time.

Exactly how does Cardio Exercise Reduce your Fat Stores?

Regular cardio training enhances the body's ability to burn fat for
energy both at rest and during activity. Not only do you burn extra fat
calories during aerobic exercise but regular training has a long-term
effect on your body's metabolism.

For example, regular cardio training increases the body's production
of the enzyme lipoprotein lipase, which breaks down fat into its
component fatty acids. These fatty acids are released into the
bloodstream and transported to other tissues such as muscle where they
are taken up by the cells, transferred into the mitochondria and broken
down to release energy. Thus, cardio training increases the body's
ability to break down fat. The more aerobically fit you are, the greater
the percentage of fat you burn at any given exercise intensity. Just as
you can train your muscles to become stronger and bigger, so you can
train your aerobic system to burn fat more efficiently. Including
aerobic training in your strength-training program will therefore help
you to achieve and maintain a lower body fat percentage and better
muscle definition.

However, the benefits of high-intensity training don't end with your
workout. Following exercise, your metabolic rate remains elevated above
resting levels for some time as your body replenishes its energy
systems. This 'excess post-exercise oxygen consumption' (EPOC) is fueled
almost entirely by fat. Following low-intensity training, the EPOC is
very small. On the other hand, the EPOC following high-intensity
training may be quite large. Also, high­intensity cardio can lead to a
significant increase in the resting metabolic rate (RMR), when performed
at least three times a week. That means you continue burning more
calories throughout the day, even when you are at rest.

What is the Best Fat Burning Exercise?

While all forms of aerobic activity burn fat, the best method for
burning fat - and simultaneously increasing cardiovascular fitness - is
high-intensity interval training. Performing a series of intervals at
80-90% MHR (maximum heart rate), or an RPE (Rating of perceived
exertion) of 8-9 (very hard), as opposed to maintaining a steady
intensity, burns up to 50% more fat than low-intensity exercise. But
before you rush into it, you must be aware that this type of training is
only suitable for very well-conditioned athletes and should not be
attempted by beginners.

Once you have built up to it, high-intensity interval training is a
very effective way of improving your body composition. Not only does it
burn more calories during your workout compared with low-intensity
training, it produces the greatest EPOC (excess post-exercise oxygen
consumption) and speeds up your metabolic rate for some time after your
workout.

Interval training can easily be applied to any mode of exercise -
e.g. running, cycling, stationary bike, stepping machine or any other
cardio machine. During the interval phases, you increase either your
speed or the resistance of the machine (e.g. the incline of a treadmill
or the 'level' setting on a stationary bike) in order to reach the
required RPE (rating of perceived exertion) level of 8-9 or 80-90% MHR
(maximum heart rate). This is maintained for 15 seconds-3 minutes,
depending on the intensity, followed by a recovery period at an RPE of 4
(somewhat hard) or 60% MHR for 30 seconds to 3 minutes. An interval
training workout is detailed in our fat burning workouts section.

Is it Possible to do too much Cardio Exercise?

More isn't always better, as excessive cardio can result in muscle
breakdown and a loss of muscle size and strength. During cardio
training, small amounts of protein can be used for energy, although the
misconception that it significantly depletes muscle mass relates more
directly to poor dietary habits.

The biggest problem is the combination of dieting - or an inadequate
calorie intake - and excessive cardio. Dieters who go overboard with
cardio training don't realize that a large proportion of their weight
loss may be due to muscle loss. When the body doesn't get enough
calories it draws upon its reserves, mainly in the form of fat 
but also from protein, which is found in muscle. Too much cardio takes
calories away from muscle growth and you can end up literally
canabalising your own muscle tissue to help your body meet its energy
needs. That's the last thing a strength trainer wants.

For this reason cardio should be done in moderation, as per the guidelines detailed above. As we have seen, moderate amounts of cardio will help you lose fat, and give you numerous cardiovascular health benefits.

When is the Best Time for Cardio Exercise?

This depends on your individual lifestyle. Choose a time of day that
fits in well with your daily schedule; that way you will be less likely
to miss a workout.

If fat burning is your main goal, the best time to do your cardio
workout is first thing in the morning. There is evidence that, when
performed on an empty stomach, cardio enhances fat burning during and
after your workout. According to research from the Human Performance
Laboratory at the University of Texas at Austin, fat burning is
suppressed when carbohydrates are eaten during the six hours before
exercise. This is due to the rise in insulin levels in the blood (caused
by carbohydrates), which suppresses the breakdown of fat stores in
adipose tissue and reduces the release of fatty acids into the
bloodstream. Thus, fatty acids are less readily available as a fuel for
the exercising muscles, an effect that can last for several hours after
eating carbohydrates. Doing your cardio exercise after a period of
fasting (e.g. first thing in the morning), when blood insulin levels are
relatively low, will optimize the rate of fat breakdown and fat
burning, and would be a more effective fat-burning strategy than doing
your cardio exercise later in the day after you have eaten a few meals.
However, it is more important that you fit your cardio exercise
comfortably into your daily schedule than risk omitting it if you are
unable to fit it in in the morning.

Research suggests that it may be better to perform your cardio and
strength training as separate sessions to minimize catabolism (the
breakdown of lean mass). But if you prefer to do both in one session,
complete your weight­training workout first when glycogen stores are
high. Performing cardio prior to your strength­training workout may be
counterproductive, resulting in reduced strength and early fatigue due
to muscle glycogen depletion.

<<Previous Page | Page |  | 2