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Effects of exercise on the body

Effects of exercise on the body
The effects of exercise on the body can have both positive and negative aspects that you should be aware of. You should be aware of and able to management how you exercise and how it makes you feel. This article will hopefully help you recognise many of these effects.

Firstly, exercise can have many health benefits, which include:

  • Weight control/management (increased metabolic rate)
  • Cardiovascular health
  • Disease prevention/reduction
  • Strength gain
  • Increase endurance
  • Increase flexibility, agility, balance and co-ordination
  • Increase joint/tendon/ligament strength
  • Increase muscle mass
  • Physical appearance
  • Self confidence
  • Mental health
  • Help with daily tasks – more energy
  • Increased libido
  • Help to control insulin and leptin levels
  • Improve nerve connections
  • Good for your mood
  • Improve blood flow and volume
  • Increases lung capacity and breathing rate
  • Make your heart stronger
  • Increases cell regeneration
  • Improve bone density
  • Improved recovery from physical activities
  • Improve self esteem and confidence

As you get older, much of those listed above actually starts going the other way. By doing exercise you can slow down and actually improve much of the above, even when the body is looking to do the opposite.

So what actually happens to the body during and after exercise?

Well first your heart rate increases, your body warms up, your breathing gets faster and deeper….those are the most obvious. But there are other physiological processes that take place, depending on the type of training/exercise you do.

Your heart and exercise

Well let’s start with the most important organ in the human body, our heart. Depending on the type and intensity of your workout, various adaption’s can happen with your heart. Like your skeletal muscles, your heart is also a muscle, therefore when it is worked it will adapt and become stronger. The working of the heart muscle is a cardiovascular activity, which pumps your blood around the body. When your heart becomes stronger it is able to push more blood around the body and becomes more efficient. This efficiency also means you have a slower resting heart rate. Other benefits of a healthy heart include (potentially), helping to fight heart disease/stroke, improves blood flow, lowers blood pressure, lowers bad cholesterol and fat levels.

Please also see the cardio article, more importantly the blood pressure article and even more importantly the heart article for more information about the heart in regards to exercise.

Your lungs and exercise

Your lunges are what supplies your body and muscles with oxygen, which provides energy and removes carbon dioxide (waste produced from breathing). Your lunges take the oxygen from the air that we breathe in and transfers it into your bloodstream. When you workout, your muscles require more energy, hence more oxygen is required, so you breathe more rapidly and your heart beats faster. A healthy lung has extra capacity in reserve, therefore you don’t feel as out of breath as someone with a less healthy set of lungs. Exercise helps make your muscles more efficient and therefore require less energy, while exercise that creates an aerobic stimulus can also help condition your lungs to increase the amount of oxygen it can handle (VO2 capacity). Please see the separate article on lungs.

Blood lactate and lactic acid

Blood lactate¬†happens when lifting weights or working a muscle repetitively. In order for your muscles to work it requires oxygen to be supplied to that muscle to breakdown glucose for energy. However as you continue to work a muscle in a non-stop manner, oxygen cannot be supplied fast enough and so your body will then start to create lactate to use as energy. When too much lactate is produced and unable to be used up it becomes acidic (lactic acid) and you will then feel what is called the’ burn’ in your muscles. This is a natural process and it’s a way for your body to tell you to stop in order to protect itself. But don’t confuse real pain with the discomfort of the burn. The burn should only be present for a short period and disappear soon after you have stopped the repetitive activity.

The pump (vasodilation)

As mentioned above, when you work a muscle repetitively it requires oxygen for energy. The so called pump happens as more blood is needed to transport the oxygen to the muscle. The blood vessels dilate and more blood fills the muscle and then hangs around quicker than in leaves, hence your muscles begin to swell. This generally happens with higher rep training due to the requirement for more oxygen and can vary depending on which muscle you are training. Needless to say it is a temporary increase in size and as soon as the muscles start to recover, the blood level in the worked muscle will return to normal. Whether the pump is necessary or not to invoke hypertrophy has been hotly debated by many. It has however been shown to increase growth hormone production and protein synthesis. Now that doesn’t mean that higher reps are superior to heavy low rep training, it is simply a different way to stimulate muscle growth. You should aim to use various rep ranges to fully work a muscle and not look for the ‘pump’. Your goal should determine your workout routine plan.

DOMS – Delayed-Onset Muscle Soreness

DOMS normally occurs 24-48hrs after you have worked a muscle, but can start as little as a few hours after and can last for more than 96hrs after a workout depending on how hard you have worked a muscle or how used to a specific exercise or stimulation a muscle is. DOMS has nothing to do with lactate/lactic acid which is a chemical process, what causes DOMS is mostly the result of a muscle being stretched under tension (muscle trying to contract while lengthened), which causes micro muscle tears. These tears happen during the process of exercising a muscle beyond its normal working capacity and/or by a muscle that is not accustomed to a specific exercise. Many experienced trainers rarely suffer from DOMS as their muscles have got used to the stimulus of exercise and desensitised to the stress placed up on it. When DOMS occur, the muscle damage caused will result in the release of free radicals, create inflammation, make the muscle tired and weak, limit its range of motion and of cause make it sore while in the recovery process. Oddly enough DOMS is also not a sign that you have worked a muscle effectively, you can still grow or exercise a muscle quite effectively without getting DOMS. You can avoid or reduce DOMS by not over stretching a worked muscle in the eccentric portion of an exercise and by increasing the intensity of an exercise gradually over a period of time. Recovery from DOMS can be achieved my getting adequate rest, gentle massage, heat and sometimes light activity can help speed up the recovery process from DOMS. Read more about DOMS here.

CNS (Central Nervous System)

The CNS is a part of the brain and spinal cord and it connects, coordinates and activates our muscles. Your exercise performance can be significantly affected by how efficient your CNS functions are. Warming up and prepping a muscle with a short explosive movement can stimulate your CNS to get it ready for improved performance in an exercise (as long as you don’t fatigue the muscle during the warm-up).

CNS fatigue

This can occur quite easily with both high intensity and endurance training where you either push yourself too hard, for too long or return to training a muscle or the body before it has recovered.

Good nutrition, supplementation and stimulants can help to provide the best nutrients to enhance the body’s response to stresses and counter the effects of CNS fatigue. Caffeine, carbohydrates and electrolytes have been shown to help work against fatigue from exercise.

Over-training / burnout

(Please note I am not referring to Overtraining¬†syndrome). For the purpose of this article, I’m using the word over-training and burnout as the same meaning to each other. Over training is where you have worked your body too hard and have not been able to recover from previous workouts. Over training normally occurs over a period of time and is an accumulation of unresolved stress over that period. If you haven’t recovered from your previous workouts and continue pushing your body then you may well make no progress and may even go backwards. But equally it may even start to affect your health negatively. You will know you are over trained when you become tired more easily, both during a workout or even rested. You will also have reduced performance, weakness, sore muscles, get ill more easily, find it difficult to sleep, have an elevated or even slowed rested heart rate, get injured more often, lose weight and muscle and may no longer be motivated or you may be in a bad mood. You need to make sure you give your body sufficient rest between workouts, rest a muscle a minimum of 48hrs before working it again, don’t work out too many days in a row if you are prone to fatigue, listen to your body, get more rest/sleep and pay attention to your nutrition. If you are suffering from over-training or fatigue, get more rest, take a week or so off training, have a massage and/or re-evaluate your training routines and nutrition plan.

Fat burning and exercise

Exercise is the quickest way to burn body fat and with the right nutrition can transform your body’s appearance considerably. There are in fact two ways to burn body fat through exercise. The first way is through long steady state aerobic type workouts. It does this as your body naturally uses a combination of fat and carbohydrates for energy and working out in this fashion for more than 30 minutes will encourage the body to use both at the time of the workout and of course these longer workouts can burn more overall calories. The other and more popular method is with high intensity interval training (HIIT). HIIT can be done with cardio and/or weights and is anaerobic. It uses up more stored muscle glycogen and then shifts to more fat burning as time goes on and the glycogen stores get depleted. The high intensity of these workouts ramps up the metabolic rate and forces the body to continue to burn more fat cells for considerably longer than steady state cardio (for more than 24hrs after your workout). Steady state is ideal for the overweight/obese or those with medical conditions that do not allow them to do intense workouts. Once they are fit/strong enough then a move to more intense exercise will be more beneficial. HIIT is best for all others, best for getting the metabolism going, best for long term fat loss and getting lean and retaining muscle. Please also see cardio vs resistance training for fat loss.

Adaption (beginner and experienced) progress

Science has a way of showing the benefits in the lab, but very few of these research/experiments will be on long term effects and I want to get into that a little here. When you first start working out and I’m mainly talking muscle gain and performance, it is hard going however your body likes to try to adapt quickly and therefore changes can happen quit quickly in the beginning (a lot of research is based on these findings). Your body reacts to these new stresses by building bigger and/or stronger muscles, making your bones bigger and tendons stronger, increasing your cardiovascular capacity and much more. However, as the body starts adapting over a longer period then more effort is required to continue to make progress. This happens because your body both gets more efficient and also gets used to the stresses imposed upon it, making it more difficult to make further progress. This is why people hit plateaus and need to change things up to change the stresses to the body. In order to keep progressing you must find various ways to stimulate the body. To learn more about making progress continue to read the subsequent articles.

Now with all this talk about the benefits and the adaptability of the body, I want to quickly mention here about the importance of proper training and the effects of not doing things right. Make sure that you understand any exercise you do and its technique. Read my articles and learn about how to properly arrange your workout routines and how the body reacts to the stimulus you are placing up on it.

Pain and exercise

It’s important that you recognise when the pain you feel is occurring due to an injury. Symptoms of an injury could include:

  • Painful ache
  • Sudden sharp pain
  • A constant pain that will not subside during a workout
  • Pain that lasts for more than several days
  • Swelling
  • Red/blue bruising (possible muscle tear)
  • Very limited range of motion
  • Reoccurring discomfort (could be an underlying issue, such as tendon/joint problems)
  • Sudden weakness (can occur for such things as a rotator cuff injury)

There may be other symptoms, but you need to be careful that any discomfort you are feeling is down to hard work and not an injury, as these can cause both short term and long term issues that will affect not just your workouts, but also beyond.

One other thing I’d like to mention in this section, is that lifting heavy weights can cause your muscles to become tight and knotted and lead to injuries if these kinds of issues are left unchecked. A visit to a physio therapist can often prevent/reduce or even fix such issues. This also includes issues associated with heavy weights that place stress on the body’s spine and again a visit to a chiropractor for an adjustment may be needed.

Exercise adrenaline

When you workout intensely or apply new stimulus to the body you can often release the hormone adrenaline from the stress created. It helps dilate your blood vessels, open up your airways and increase your heart rate, increasing the flow of blood and oxygen to your muscles. Adrenaline can give you a temporary boost in strength along with the release of endorphins, dopamine and norepinephrine. These other ‘feel good’ chemicals can reduce pain and also keep you going in your workouts.

Natural training

Steroids vs natural gains – no I’m not going to be talking about steroids. If you didn’t already know it, steroids alter the results dramatically, see any before and after image of a steroid using bodybuilder and you will see the difference. It goes without saying, the risks far out way any gain, steroids can and do cause many health issues and even death. With that out of the way, this little bit is about being realistic, given your ‘natural’ genetic predisposition and ability and motivation to following a good nutrition and workout plan.

Being realistic will help keep you on track and avoid being disappointed, ignore what you read or see with regards to professional bodybuilders/athletes. In the real world of us mere mortals you need to realise that you must maximise the amount of stress appropriate to your goals and yet be able to recover sufficiently to resume training. Gains will be slow, but they are honest gains that will last a long time. As a very rough guide a natural trainer will need to keep their workouts preferably under 1 hour per session. Those looking to gain weight and muscle and are ectomorphs should workout closer to 30 minutes. Working out for too long puts too much stress on the body and releases cortisol, a hormone that can have a negative effect on your gains and body. Also lengthy workouts also impact your CNS and also increase the risk of injury due to overuse of your joints and tendons. Muscles require at least 48hrs rest before being hit again, so hitting them 2 times a week can fit into most trainers routines and for those doing full body workouts can go up to 3 times a week. The harder and longer you train a muscle the more recovery time it will need. Nutrition as a natural trainer is very important, not just for making gains, but for recovery also.

HGH and testosterone

Resistance training, especially lifting heavy weights can and does increase human growth hormone and testosterone levels. What’s more the more muscles you can hit in a single session has been found to have a greater effect on these increased levels. It is however important to note that those with naturally higher levels of HGH and testosterone (i.e. the young) will not see huge increases to their levels, as the body has a natural level, but certainly the older we get, the less we produce of both and resistance exercise can greatly help in reversing this loss of production from our bodies.

Protein synthesis

Far more important in the battle to increases muscle mass is protein synthesis. When you lift weights your body actually breaks down muscle, you become catabolic. At this stage your body wants to repair these muscles and with the help of increased HGH and testosterone levels during exercise, it is able to take an increase in protein consumption and able to synthesis extra protein. This increase in protein synthesis lasts between 36-48 hours after a workout before returning back to normal. If enough stimulus with heavy enough weights (read that as heavy enough, but not necessarily heavy) has been placed on the muscle, the repair of the muscle will see it also increase in size (hypertrophy).

Hypertrophy and hyperplasia

As mentioned above, when you give a muscle enough stimulus with heavy enough weights you breakdown your muscles and it gets repaired with an increase in size creating hypertrophy. Hypertrophy is simply an increase in the size of a cell. Hyperplasia on the other hand is an increase in the number of cells. It is thought that Hyperplasia only occurs once you have reached your bodies maximal hypertrophy capacity and possibly mainly seen in those who take steroids.

Body clock and best time to exercise

Our bodies run like a clock, it recognises certain times of the day to wake up, eat, sleep, be more alert etc. It also likes to regulate our bodies temperature, hormonal response, heart rate and mood. It therefore appears that there are times of the day when it would be more optimal for a workout. If you want to maximise your performance, recognising when you have more energy may help. However don’t get too hung up on this, as I have found working out at the most convenient time to be key, especially if you start to workout at the same time on a regular basis, as your body will adapt and recognise this as the time that you workout at.

For those that are looking for an answer to the question, well unfortunately some research has shown it best to workout in the late morning, while others have had better results with late afternoon/early evening workouts, especially if strength training. So pick the time that suits you.

Muscle twitches (fasciculation’s)

There are a few reasons that our muscles might twitch during or after a workout. They include not being fully hydrated and/or an imbalance of electrolytes (minerals), which can also lead to shaking, spasms or cramps. You can also get twitching from muscle fatigue, stress or even if you haven’t warmed up adequately. Normally, having twitching muscles isn’t a problem, but I recommend staying hydrated as best as possible and if it is something that happens too often to you, either drop caffeine completely post workout or altogether. Stretching and massage can also help.

Hitting the wall

More associated with endurance sports, but I’ll mention it here for those that do partake in such events/routines. Hitting the wall is the point at which you deplete your glycogen stores and suddenly become fatigued and loose energy. If you are taking part in endurance style training, ensure adequate nutrition and hydration before and during your routine. Preferably good solid food meals of complex carbohydrates, protein and fats during the day and up to a few hours before your routine and more simpler carbohydrates and quick proteins before and during the workout. Drinking a sports drink may also be helpful during an endurance event for quick carbohydrates and rehydration or simply just water.

EPOC (Excess Post-exercise Oxygen Consumption)

EPOC is an increase in oxygen intake after intense exercise. After you have had an intense ‘anaerobic’ workout, your body is still working to restore itself to a more normal state and needs to replace the oxygen debt created by a fast paced workout. Your metabolism is also elevated and in order to supply much needed nutrients to recover from your workout, your body requires more oxygen to carry out this process. This process also burns more calories and a greater amount of fat calories. This is why HIIT and/or heavy lifting with minimum rest periods can burn more fat calories than steady state cardio/workouts, as it carry’s on burning those calories well after the workout (also known as the after burn).


There could be several reasons why you yawn during a workout. Some would say it is a lack of oxygen getting to the brain, but often it is due to fatigue and tiredness. It is also a way to increase the blood flow to the brain and also help cool it down. Most of the time there is nothing to worry about, however if you yawn excessively then there may be an underlying medical condition and it may be best to seek professional advice if in any doubt.

Heart palpitations (flutters and skipping a beat)

When your heart pumps blood it requires an electrical impulse to do so. Heart palpitations are a misfire normally caused by an electrical impulse created at the wrong time and can often be due to a lack of oxygen and poor blood flow. It is more likely to occur after a hard workout, however if you get it on a regular basis or during a workout, it may be best to get a health check up with your doctor.

Exercise induced asthma (exercise-induced bronchoconstriction)

If you have suffered from a shortness of breath where you are wheezing and coughing, you could be suffering from exercise induced asthma. When you workout intensely you tend to breathe faster and can breathe cold and/or dry air, which can lead to the airways to your lungs narrowing and of course this will greatly affect your workout performance. Sometimes this can also lead to the formation of mucus and may also be made worse in cold, damp or dusty conditions and if you suffer from hay fever/allergies. If this is the case for you, it may be worth seeing a doctor to see if there are any underlying problems or to obtain an appropriate inhaler. Other things you can do to avoid this, are doing a proper warm up, don’t work out in a cold damp or dry place and generally look to improve your overall nutrition and health.

Heat and dehydration and sweating

Heat increases the body’s temperature, add exercise and you can quickly become over heated. It can not only affect your performance, but also lead to cramps, faintness and nausea, heat exhaustion, heatstroke, weakness, erratic heart beats and more. Your blood vessel will dilate making your skin warm and then your body will sweat to try to cool down. This is when it is most advisable to stay hydrated and drink plenty of fluids to replace the fluid lost through sweating. Make sure you are also wearing appropriate gym wear and workout in a well ventilated place and avoid working out in the midday sun if this is an issue.


So while this article may seem like you can suffer from a number of issues while working out, I’m merely pointing them out to you for you to be aware of them and most of them can be managed quite easily. The fact that I suffer myself from heart palpitations on occasion and have been diagnosed with a heart murmur hasn’t stopped me, I also have suffered from exercise induced asthma in the past and experienced a few of the other exercise induced effects at some point. But many of these symptoms have faded away as I have increased my strength, nutrition and health over the past year or so. There should be no excuse for not pursuing self improvement, just be safe and aware of any potential effects that exercise may have on you.

Please also see the energy used during exercise article.