Benefits of High Intensity Workouts


You have all probably worked out that I like to use interval training in my classes, which provides you with periods of time where you are working at a high intensity. This is otherwise known as HIIT – High Intensity Interval Training.

One reason is the time frame of 75-90 minutes sessions, so the interval training gives you a greater training effect by giving you cardiovascular improvements in a short period of time. Although HIIT training is also very effective if you only have 30 mins to spare (as long as you are warmed up).

I also like to give you a strength and endurance component in your class as well, which is so important – this ultimately means the time isn’t there to do a whole hour of jogging or road runs etc that are mainly low intensity cardio, for the duration of the class. Sure, you will still have had a great workout and kept your heart rate at a good level of elevation for about 45-50 mins, but adding the intervals as well gives you a good variation in your training and trains different physical systems in your body.

There is no valid reason that a healthy person should maintain a low intensity program unless they simply aren’t interested in seeing real results, or have a medical reason to not do so. A low intensity workout, where your heart rate is only around 60% of its maximum rate (remember the rough guide that your maximum heart rate is 220-age) is pretty inefficient for anything other than slow and gradual (if any) weight loss. It will not help you boost your metabolism, and won’t provide much increase in muscle mass, and won’t really build any strength or endurance. In short – you are not getting out of your comfort zone so your body is not under stress. For your body to ‘overcompensate’ and get stronger to counteract the ‘stresses’ you impose on it, it needs to be pushed harder than it is used to tolerating. This is how you get faster, fitter and stronger.

A high intensity workout is defined as any exercise which pushes your Heart Rate up to 75% of its maximum or more, and is infinitely better for nearly every aspect of your overall health. Remember though that there is no need to be scared by your ‘maximum heart rate’ if you are a healthy person as you are not going to damage your heart if you go up to or over this heart rate. The 220-age formula is only an estimate and depends on your individual physiology, genetics and current fitness level. So you may find yourself exceeding this number.

Low Intensity Exercises are beneficial for warming up and cooling down, before and after high intensity phases. Low intensity exercises are also good for the elderly, anyone recovering from injury or illness, someone who is significantly overweight or unfit, or someone that is just beginning to exercise. The physical benefits from Low Intensity exercise are many, and include an increase your capillary density, it strengthens the skeletal muscles that will help you withstand more intense levels of training, and will help you improve your aerobic fitness. This is compounded when resistance training (weights) is also added to the program. Working at a low intensity (ie walking or jogging) for a long period of time helps the muscles ability to consume oxygen and work better for longer.

You may have heard that your body burns more fat when it is working at a low intensity. And this is true. However, nothing is ever that easy. If it was we’d all be lean and mean from just strolling around the block. To burn the same amount of fat doing low intensity exercise as high intensity exercise takes about 3-4 times longer – and does not give you the same training or physiological changes. 30 minutes of high intensity or 2 hours of low intensity for the same if not less of a result???? What would you choose? Both intensity levels burn calories and of those calories, a percentage of them is fat. So technically speaking, low intensity burns a higher percentage of fat (around 50%) whereas a high intensity workout burns around 40% fat. A higher intensity workout burns a higher number of calories overall than a low intensity workout, and then the ‘afterburn’ (post exercise) of calories is also higher due to a metabolism that is elevated for longer, so the high intensity will give you a better result. This is called EPOC – Excess Post Oxygen consumption. We all want it – it burns fat all day!

For example, you may burn 100 calories by walking for 20 minutes. Walking is low intensity, so 50% of those calories are fat, meaning that your 20 minute workout has resulted in burning 50 fat calories. On the other hand, if you burn 160 calories during 10 minutes of high intensity exercise, 40% of those 160 calories are fat, so in 10 minutes you have burned 64 calories! It might only be 14 calories difference, but it was achieved in half the time! Imagine if you continued your high intensity (which you often do in my sessions) for 30-40 mins!

In saying this, a great number of healthy people that do frequent low intensity exercise are missing out on the major benefits that a high intensity workout can give. Don’t get me wrong – low intensity is ABSOLUTELY better than nothing, a good long walk that last for an hour plus is great exercise, however you can achieve much more in half the time by increasing the intensity.

Some people are not ready for high intensity exercise however and need to build up their fitness to tolerate it, or they just may not enjoy it, so remember –