April 27


What happens to your body when you start exercising?

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Have you ever thought to yourself, "what actually happens to your body when you start exercising?" I was asked this by a FIFO work colleague just a few weeks back - he wanted to know what we meant by getting fitter. So in today's post we'll explore how exercise changes your body physique, muscles, heart and even your mind.


I'm paraphrasing, but you might have heard before that if exercise was drug, it'd be the most valuable pharmaceutical ever developed. Basically, exercise does more for your brain and body than you could possibly imagine.

So why is exercise so good for us?

If you look at the most successful people in all walks of life, they tend to share one core habit. Yip, you guessed it - they exercise. In his book, The Power of Habit, award winner Charles Duhigg talks about what he calls "keystone" habits. Essentially, these keystone habits can influence change in every aspect of our lives if we practise, develop and apply them. Exercise is a keystone habit. If you've ever come across someone with strong self discipline, they likely go to the gym regularly or complete some form of exercise.

For most, the physical benefits of exercise are obvious. For example, you look better, probably lose weight, become leaner and may gain some muscle. Generally speaking, you become fit.

We can easily observe these changes with the naked eye. However, when you start exercising, more happens to your body than just what you see on the surface. For example, it's common for people who exercise to report they feel happier, more motivated and less depressed.

As a result, exercise is often labelled as a 'miracle drug.' In fact, experts recommend exercise as a treatment for memory loss, depression and insomnia. Furthermore, it's also encouraged in therapy for Alzheimer's and Parkinson's disease.

How exercise affects our hormones, which essentially control our body

When we exercise, our body naturally produces hormones. Some of these include serotonin, endorphin and brain-derived neurotropic factor which plays an important role in growth and survival of brain tissue.

In their own way, each of these hormones help:

  • reduce stress levels
  • lift your mood
  • aid in better sleep
  • improve learning
  • increase confidence levels

Especially when you start exercising for the first time. On the other hand, if you return to exercise after a long break you'll feel more alert and energised. In effect, you're ramping up your heart rate which boosts blood flow (and oxygen) to your brain.

As a result, your body releases dopamine - a special brain chemical responsible for, among other things, motivation. If you've ever felt lazy or tired and don't feel like doing anything, it's likely you're experiencing a dopamine deficit.

In essence, dopamine is responsible for the feeling of satisfaction when we accomplish something. As a result, dopamine is responsible for our motivation and attention. It makes you want to do things. Furthermore, it reassures you that whatever you did was worth doing.

So if you find yourself experiencing a lack of dopamine you might find it hard to get things done. Essentially your brain isn't getting enough fulfillment to justify doing them. However, when you exercise you directly raise the amount of dopamine in your blood. As a result, you'll suddenly feel motivated and energised rather than tired and run down.

Now let's look at the physical effects of exercise - what happens to our body when we work out?

We might not see the physical effects of exercise within the first few weeks of workout out. The chances are, even after a month, there might only be a few visible results. However, the real changes are happening under you skin.

Throughout the time you were working out and exercising, biological changes are taking place.

Firstly, after a few weeks of starting a cardio routine, you will notice that you have more energy. Your metabolic rate will increase and you will have more mitochondria in your cells.

One misconception around exercise is that exercise causes weight loss.

Technically, this isn't true. Exercise causes you to increase muscle mass and muscle tissue has more mitochondria. As a result, mitochondria burn more energy. They're the part of your cells which convert the carbohydrates, fat and protein from your diet into fuel. Your muscles use this fuel to do their job.

Research shows that people can increase their mitochondria levels by up to 50% after around 6 to 8 weeks of regular exercise.

The more mitochondria you have, the more energy you can produce. At this point, you will definitely notice a change in your fitness. For instance, you might find you can easily climb the stairs that used to leave you puffing and panting.

Within a month, your muscles will begin to grow and become stronger.

Sometimes, this isn't obviously visible. However, you will feel the difference in strength when you exercise and work out. This is another aspect of our metabolism revving up.

As a general rule, muscle cells need more energy than fat cells. Even when you're not exercising, muscle will still consume more calories than fat.

So, the time you spend working out continues to reap benefits even after your exercise session ends.

Regular exercise improves your VO2 Max

Data from the US National Academy of Science, Engineering and Medicine shows that if you consistently perform cardio exercise for a period of six months, you can expect a 20% increase in your VO2 Max.

Generally speaking, we use VO2 Max and an indicator of fitness level. Essentially, VO2 Max is the fastest rate at which your body can transport oxygen to your muscles. Basically, the higher your VO2 Max, the fitter you are. Having a higher VO2 Max means you should be able to run further in a shorter space of time. Your muscles can get more oxygen delivered faster than before. As a result, your running pace increases.

As a general rule, a 20% increase in VO2 Max means you should be able to run 20% further in the same time span. For example, if you used to run 5km in 30 minutes, a 20% increase in VO2 Max means you can now run the 5km in 25 minutes.

Or, 6km in the 30 minutes.

Finally, exercising regularly can increase the strength and size of your heart. After all, your heart is a muscle itself.

When we exercise, our heart rate increases and so pumps more blood than it normally does.

Consequently, your heart muscle grows stronger, reducing your chances of having a heart attack. Usually, this strengthening effect happens after about 6 months of regular exercise. Conveniently, this is around the same time as the physical effects become noticeably evident.

How starting exercise affects your brain, as well as your body

Some of the physical effects of exercise aren't visible. This includes the increase in blood supply to your brain. Once it gets more blood and oxygen, your brain can work more efficiently. As a result, it can focus better when doing activities.

Furthermore, exercise encourages your body to form and develop new brain cells. In turn, this improves learning and memory.

Additionally, during exercise, your body releases endorphins.

Endorphins are famously known as the feel good hormones. However, this is a little inaccurate. Endorphins counter any feelings of stress you might be experiencing. As a result, when they are released into your bloodstream, endorphins lift your mood and you get a sense of happiness.

Ultimately, exercise can alleviate feelings of stress you may have before the workout. When you exercise consistently, your body gets a regular supply of endorphins and dopamine. Hence, you are left feeling supercharged and energised, ready to take on whatever life throws at you.

Once you start to exercise, you'll sleep better

As yet, science hasn't quite mapped out exactly how exercise leads to better sleep.

We do know exercise reduces anxiety. Additionally, we know that restless sleep is usually caused by depression and anxiety. Exercise helps reduce symptoms of depression and anxiety by the effect of endorphins and dopamine.

It makes sense then that you should get better sleep and symptoms of insomnia decrease if we are less anxious.

Furthermore, when we work out our body temperature increases. Our body then has to work to get it to come back down.

Interestingly, our body also works to drop our temperature in the lead up to falling asleep.

Therefore, if we exercise before going to bed, we might get a 'double hit' of this effect, helping us to fall asleep faster. However, exercising in the afternoon or early evening has also shown to result in better sleep too.

Nature has fashioned our bodies to operate on a biological clock, our circadian rhythm. If this rhythm becomes skewed, or messed up, we can have difficulty sleeping as our body is now 'out of sync.' Problems with the circadian rhythm can cause insomnia. Exercise, you'll be glad to know, helps fix this biological clock, therefore resulting in better sleep.

Does starting an exercise regime really help us to feel more confident?

Honestly, yes!

Short term, exercise lifts your mood. We've discussed the release of endorphins already. Additionally, wiith exercise, we also get a moderate increase in serotonin levels.

The regular and constant release of these hormones makes you feel good about yourself. You'll become happy. This, amazingly, also increases your confidence.

Even without seeing any physical results at the beginning, exercise improves your body image.

Once we make the decision to get healthier and are proactive in getting fit, you'll become proud. You'll start to feel great about yourself, achieving a real boost in self confidence.

Ultimately, once the physical changes associated with exercise are noticeable, your confidence explodes. In fact, some people attest life changing results to exercise, both physically and in their mental attitude towards life.

Exercise helps to renew your feelings of worth. Our bodies respond to make you feel great and happy about yourself.

Exercise improves your confidence. It can and will improve your performance at work or school. You might even find it saves you money as you're likely to be in better shape with less healthy problems and medical expenses.

Clearly, exercise is good for our mental health as well as our physical well-being. In all probability, if you exercise for just 3 hours per week consistently, you'll live longer than you otherwise would. Additionally, that extra time spent living will likely feel more happy and fulfilling.

About the author

Paul Stokes

Paul Stokes BSc (Hons) is a Certified Personal Trainer, Accredited Sports Nutritionist, qualified Exercise to Music Instructor, Precision Nutrition coach, Massage Therapist and teaches 8 of the Les Mills Group Exercise programs.

He currently works in the Oil & Gas industry as a Wellness Coach, imparting his vast knowledge and experience to improve the quality of life of several hundred offshore workers.

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