When you read through the exercise guidelines, the recommendations almost always involve the words “moderate intensity”. But why is this the case? Let’s delve into what research has explored to shed some light into why moderate intensity exercise is best.
Research throughout the years looking into the various aspects of exercise has helped to give us insight about what types of exercise are best suited for the different health benefits. Let’s start with weight loss. Many years ago it was discovered that different intensities of exercise changed our bodies primary choice of fuel. This was the start of the “fat burning” programs that became standard on exercise equipment like treadmills and bikes. It is true that at lower intensities (around 60% of your maximum) your body prefers fat as a fuel source and at higher intensity it uses more carbohydrates. However looking at the bigger picture, exercising at a lower intensity translates to less overall energy being needed and used.
More recent views on weight loss recommended including moderate intensity exercise for a good reason. Overall energy expenditure is often higher when exercising at a moderate intensity for a few reasons. Firstly to achieve the same energy expenditure using lower intensity exercise, the duration of exercise would need to be substantially greater. Not only this but any additional energy we consume through food is more easily stored as fat as we don’t need to replenish our carbohydrate stores. Secondly many people simply do not have a high enough level of physical condition that allows them to achieve or sustain vigorous exercise for the lengths required to be equivalent.
The benefits of exercise continue to mount as the intensity and volume increase however there are a few trade offs that occur when you go beyond moderate intensity. Perhaps the most important trade off is safety. Taking your body towards its limits always increases the risk of an adverse event.
Another well known trade off for high intensity exercise is short term immune system function. While moderate intensity exercise boosts your immune system in the short term, high intensity exercise does the opposite. This can be detrimental to your health especially when combined with high stress levels.
The good news is that no matter what intensity it is at, something is always better than nothing. The minute you do more than rest you immediately begin improving your health significantly. However if you want the most bang for your buck, then moderate intensity is the way to go.