I have made exercise a routine part of my life for many years now. I admit I have become somewhat addicted to the endorphin rush I get from a long sustained workout. But one thing I don’t do is exercise classes. For me part of the allure of exercising is having time alone where I can let my mind wander, or better yet, turn it off completely. I find it becomes meditation in motion.

So imagine my surprise when I tried out a new type of exercise (which just happened to be in a class format) and loved it. The class was so much fun that I forgot I was jointly dripping sweat with a bunch of other people. As I settled in the second week though, I started to look around. Being a physiotherapist I just can’t help myself. I observe how other people move, what they are having trouble with, and where they are about to hurt themselves. Trust me, it’s painful to see that and not say something for fear of looking like an ambulance chaser.

Why Can’t I Keep Up?

From the chatter of the participants before class started I could guess that a good number of them were regulars and had been coming for some time. Yet most of them couldn’t keep up through the whole class. I hear about this sort of thing often from clients. They figure that doing an exercise class regularly should build some endurance and therefore it should get easier over time. It may get a bit easier as time goes by, but too often the change is very minimal and people get frustrated.

Enter the stick. As in the beat-myself-up-for-my-inadequacies stick that we women brandish so easily. Well, I am here to snatch that stick out of your hand and explain to you why this happens. It has nothing to do with your motivation level, whether you missed a class here and there, or if you ate a bag of chips last night. It has to do with one thing and one thing only – base training.

What do I mean by that?  Thankfully I don’t mean training at base camp on Mount Everest. Breathe a sigh of relief because really, no one wants to endanger the lives of those poor hard-working sherpas. By base training I mean building the physiological foundation on which all physical activity should be stacked.

Aerobic and Anaerobic Systems

Our bodies function on two main sorts of energy generation – aerobic and non-aerobic. Aerobic metabolism requires the presence of oxygen, anaerobic metabolism takes place in the absence of oxygen.

When we exercise, we start to demand more of the big power muscles of the body. This increases the oxygen demand. Our bodies react by increasing our heart rate and breathing rate to meet the demand. Nothing new here, right?  As we increase the intensity of the exercise the oxygen demands increase. If we keep pushing, at some point the demand for oxygen will exceed the supply. This is the point at which we start to work anaerobically. The significance of this switch is that anaerobic metabolism cannot be sustained for long periods of time. It uses different energy sources stored in the body, which are finite.

Grow Yourself Some Solar Panels

Think of this as a car that is powered by solar panels and a gas tank, with the gas engine only kicking in once the demand for energy exceeds the ability of the solar panels to supply it. Suppose this car can travel up to 20 kph on the energy supplied by the solar panels. As long as the sun continues to shine the car could go indefinitely at 20 kph or less. But if we pushed it to 25 kph then the gas burning engine would kick in and go until it runs out of gas.

Our bodies work in much the same way. As long as we stay in our aerobic zone where we can supply enough oxygen for our working muscles, we can sustain activity for very long periods of time (as evidenced by long distance runners). Once we switch to anaerobic metabolism our gas tank is emptying and we will eventually have to stop when we run out.

Base training of the aerobic system is the equivalent of adding solar panels to your car. This allows you to go farther or faster and work more intensely before your engine switches to finite gas. The more solar panels you add to your car the faster it can go (say now 30 kph) on the renewable energy system – i.e. the further you can get into that exercise class before you crump

Why Isn’t This Getting Any Easier?

Why then does doing the class regularly not add solar panels to your car?  This is because if you haven’t already done some base training your car barely even has solar panels. So three minutes into the class your very few, very tiny solar panels can’t keep up and you are running on the gas engine right away. You can’t train aerobically if you are moving straight into your anaerobic zone, and this is exactly what you will do if you haven’t built your solar panels first. And of course just to add the confusion, we often call these “aerobics” classes. Well, at least we did in the 80’s, but then people also had big hair and wore leg warmers so I guess we can forgive a simple misnomer.

Unfortunately the majority of the population does not have an aerobic base. If you can’t run at a slow pace for at least a kilometre without stopping, then your car is in serious need of building solar panels. It is only with building your solar powered system that the exercise class will get significantly easier.

We often refer to doing a “cardio” workout, but most of us don’t really know what that means or how to do it. Training the cardiovascular system requires that you stay in that aerobic zone, and if you haven’t trained it, it will be very small. For some people even a brisk walk may push them past it, and yet here we are doing an intense exercise class and wondering why we’re still sucking wind and not keeping up after doing it for months. As I said, put down the stick now.

Let me add one caveat here. By no means am I suggesting you give up the exercise class. A well-rounded fitness programme involves both moderate level sustained aerobic activity as well as some anaerobic power work that the class is providing. I am suggesting supplementing the class with some base training. Besides, any exercise is better than none at all.

Strengthen Your Heart and Grow Some Mitochondria

For our bodies, the equivalent of building solar panels is strengthening the network that supplies oxygen to our muscles. With regular true aerobic exercise we improve the cardiovascular system in several ways. One is by improving the efficiency of the heart to pump blood. This is best achieved by strengthening the heart (which by the way is a muscle), which allows it to push more blood out each time it pumps. This is much better than asking the heart to pump faster to move more blood since our heart rate is also finite.

Regular aerobic exercise also increases capillary density. Capillaries are tiny blood vessels that supply blood to individual cells. With regular training we actually grow a bigger network of these vessels and thus improve the rate at which we can deliver oxygen to a working muscle. Isn’t the human body amazing?  The other magic that occurs is an increase in mitochondria. These awesome structures live within the cells and metabolize nutrients into energy. More of these means more exercise before we hit the wall.

No matter what activity you enjoy, be it an “aerobic” exercise class, playing soccer, or cross-country skiing, without base training of the aerobic system, your endurance during these activities will not be great, nor will it improve with doing more of that activity since it is being done in the anaerobic zone. Stay tuned for my next blog in which I will talk about exactly how to train the base of your fitness pyramid. And in the meantime, cut yourself some slack – you just need to grow some capillaries and mitochondria.

We see the forest and the trees.


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