The Effects of Exercise on the Body
Short-term effects on the cardiovascular system
The heart has an anticipatory response to exercise where your body raises your heart rate slightly in preparation for exercise, this would help as then your muscles are already getting more oxygen than normal and can then store this oxygen by attaching it to myoglobin. This leads to having the ability to use aerobic respiration quicker compared to having no anticipatory response. Increased heart rate and stroke volume. Heart rate is the amount of beats of the heart in a minute and stroke volume is the amount of blood pumped in one beat. If these increase then more blood is getting around the body and that means that more oxygen gets to the muscles. This happens because muscles need oxygen to do aerobic respiration in response to acute exercise. These two measurements of the body can be combined to show the cardiac output, this increases from around 6 litres a minute to around 30 litres a minutes depending on the strength of your heart. This is cardiac output and this increases from rest (6l min) to about 30l min during exercise.
Because of the cardiac output increasing, there is more blood being pumped by the heart in each beat. This then causes the blood pressure to rise as with each beat more blood is being pumped and at a faster rate compared to when resting. Starlings Law is the law that your stroke volume increases in response to an increased amount of blood filling your heart, this is because the blood stretches the walls of the heart creating a stronger contraction therefore pushing more blood out. This is directly related to Starling’s Law of venous return.
Because of the increase in temperature when exercising, your body needs to cool its self down. One way of doing this is vasodilation, ‘vaso’ meaning vessel like veins, capillaries and arterioles and dilation meaning to expand, which is where the blood carrying vessels in your body expand and rise closer to the skin so that then outside temperature can cool the blood which would cool your body in turn. Evidence of this is when you go red
while exercising; this is the increase of blood close to the skin because of vasodilation. The opposite of this is vasoconstriction where your blood vessels shrink away from the skin so that your body heat is kept inside and not let out through the skin. These two combine when re-distributing blood as the vessels leading to non-important organs (stomach, spleen, kidneys) and the vessels leading to muscles open up more.
Long-term effect of exercise on the cardiovascular system
The heart muscle increases in size and strength (cardiac hypertrophy). This is so that more blood can be pumped faster. The body does this to get more oxygen to the muscles to facilitate respiration. This will help an athletes performance by making their muscles more effective and be able use them for a longer time.
Because of the cardiac hypertrophy, cardiac output increases. This is the heart rate x stroke volume, which increases because the heart is stronger and can pump more blood in one beat. This means that more oxygen is getting to the muscles.
Lower resting heart rate and quicker recovery rate. Resting heart rate is the beats per minute (BPM) while not doing any exercise and recovery time is how long it takes to get back to this heart rate after stopping exercise. Having a lower resting heart rate means that when you reach your max heart rate you are pumping more blood than others would be because you have increased your heart rate more. Bradycardia is when your resting heart rate is at or below 60 bpm, this is extremely good as with each beat your heart is supplying a huge amount of blood to the rest of your body. The resting heart rate can go down because the stroke volume is higher, so the heart doesn’t have to pump as fast to get as much blood around the body. A quicker recovery rate means that the body can recover from exercise quicker and is ready for the next exercise sooner. This is helpful in team sports such as basketball, where you have to sprint, and then have several seconds to recover and then sprint again. If the body has a quicker recovery rate it will be ready for the next sprint before the other players. A quicker recovery
rate though isn’t just due to the cardiovascular system. It is helped by the respiratory system because it can get more oxygen into the blood stream faster so more oxygen can get to the muscles that need it.
Buffering also facilitates this with it a few systems to help push back the Onset of Blood Lactate Accumulation (OBLA) which is where there is a significant increase in the lactic acid in your blood therefore decreasing the pH (should be 7.4). One system is the protein buffer system which can either donate or absorb hydrogen (H+) atoms as H+ raises/lower the pH of blood. Another is the phosphate buffer system which is made of two ions, there is hydrogen phosphate (HPO) and dihydrogen phosphate (H2PO). When your body releases HPO it absorbs H+ to create H2PO increasing pH which is the opposite of releasing the H+ in the H2PO to decrease pH. Times where your pH may decrease from added lactic acid may include doing exercises which involve isometric contractions such as the plank. This is because your aerobic system cannot provide energy quick enough to be used so your lactic acid system must which produces H+ as a by-product. This system improving (by gaining more ‘buffers’) is a prerequisite of being able to use your anaerobic system and having an increased threshold before you feel the pain from the increase in pH, this would lead to better performance as you can create energy for longer using this system before having to rest and remove the lactic acid from your system.
Excellent – well done. M2 partly achieved.
Increased number of capillaries in the muscles, heart and lungs or capillarisation. Capillaries are small blood vessels that diffuse oxygen into muscles and organs and take carbon dioxide out. If there are more capillaries in the muscles then more blood can reach into more of the muscle, therefore improving range of delivery and uptake of oxygen. This increases effectiveness and performance. It can also help release heat as capillaries near the surface of the skin widen when the body does exercise to help release heat.
Increased volume of blood and red blood cells. This helps because red blood
cells carry haemoglobin and that’s what oxygen attaches to meaning more oxygen being transported. This means that if there is more oxygen the muscles can be used more effectively and will be more powerful and the athlete will have a better performance.
Increase in the elasticity of arterial walls. This means that your arteries can expand to have more blood going through them and therefore more oxygen can get to your muscles.
With these factors in play (cardiac hypotrophy, increased cardiac output, capillarisation etc.) your overall aerobic performance increases hugely due to more blood being pumped through more and wider vessels with higher levels of oxygen in your blood. This can be seen when testing the VO2 max (the maximum amount of oxygen a person can transport while doing exercise) as a healthy untrained individual would get a result of about 18-25 60+ ml/kg/min where as a trained athlete would get around 42-46 ml/kg/min.
Overall, the heart is vital to aerobic respiration and supplying the muscles with O2 while taking away CO2. Because these changes help improve the systems efficiency and productivity your overall aerobic fitness is improved due to more oxygen being supplied by the blood and it being sent faster.
Short-term effects of exercise on the respiratory system
Increased rate of breathing. This means that more air can be taken into the lungs. This, in turn, means that more oxygen can be taken to the muscles through the blood and more carbon dioxide can be expelled more effectively.
Increase in tidal volume, which is the amount of air breathed in or out in one breath. This means that more oxygen is going into the lungs in each breath so more can go to the muscles. If this is combined with the rate of breathing increasing then there is a very significant increase in the amount of air being inhaled. This means an increase in performance from the muscles because they have more air to respire, therefore more oxygen to inhale and more carbon dioxide to exhale. This is also linked to your VO2 max which is also increased. The average tidal volume for an untrained individual is around 500 mL which can double up to 1000 mL when doing exercise where as an elite athlete can have a tidal volume of around 2000 mL when doing exercise. Have you got resting and exercise values for tidal volume?
Long-term effects of exercise on the respiratory system
Strength of respiratory muscles (diaphragm, intercostal muscles, sternocleidomastoid, pectoralis major, scalene, rectus abdominis, external obliques, internal obliques, transverse obliques) increase. This means that when the body inhales the lungs can have more room because the respiratory muscles stretch the lungs creating a wider space for air to be sucked into through diffusion. This facilitates a larger tidal volume which means more oxygen can get to the muscle which means an increase of performance.
Increase in vital capacity. This is the amount of air that can be forced out of the lungs as soon as possible. This has an advantage because if the carbon dioxide can be taken out of the lungs sooner, the oxygen can be taken in sooner. This means that more oxygen can be taken to the muscles sooner so they can respire faster and increase performance.
Normally your body controls your breathing through neural means (through your brain) but when baroreceptors (receptors measuring pressure) and chemoreceptors (receptors measuring chemical levels) sense a higher pressure in the blood due to increased cardiac output and a higher level of acid in the blood, the body releases hormones that increase the breathing rate. This then supplies more oxygen to the blood that is moving faster due to higher pressure and expels the carbon dioxide and lactic acid from the muscles which caused the change in the chemical balance.
The medulla oblongata is a key area of the brain that controls respiration, it does this by taking the information that is given by the chemoreceptors as to how acidic the blood is. If the blood is not at its normal level of acidity then it will increase the breathing rate so that the hydrogen causing the change in blood acidity can be expelled in its gaseous form. Two
other key parts of the respiratory system are the phrenic nerve and the intercostal nerve which feed information to the medulla oblongata and then pass information on when to contract and how intense back so to control the level of breathing. This causes the respiratory muscles (intercostal muscles, scaleni, sternocledomastoids, trapezius, pectoralis minor) to contract and relax more rapidly making your breaths faster, deeper and more forceful. which then initiates which breathing muscles to do what?
Increase in oxygen diffusion to, and carbon dioxide diffusion away, from the body. All of the effects above mean that this can happen with the addition of changes such as increased number of alveoli (therefore more points for diffusion to take place) and an increase in total lung volume. This helps performance because there is more oxygen in the blood stream and the muscles can respire faster and more effectively. This increase performance because it increases power and endurance.
Short-term effects of exercise on the musculoskeletal system
During the creation of energy inside your muscles, heat is produced as a by-product. This heat then warms your muscles with the aid of stretching which overall increases muscles pliability (how long it can stretch). In turn, this would lead to an increase in your range of movement (controlled by your joints) as your muscles would be able to stretch further increasing the angle of the joint. As an aid to this, more synovial fluid would be produced and its viscosity (how thick it is) would lower allowing for smoother movement due to it lubricating the joints.
Micro-tears in the muscle fibres occur when the muscles is put under stress while exercising. This is then fixed by the body providing it has the right fuel and time to do so, this then makes the muscle bigger as, like a scar, your body will not only restore it to its previous condition but add a bit more muscles fibre on.
Because your muscles need a higher amount of oxygen during exercise, your body diverts it from your digestive system etc. through vasoconstriction and
instead sends it to your muscles using vasodilation. Because there is more space in the vessels heading to the muscles now and less towards other systems more oxygenated blood is sent to your muscles.
Long-term effects of exercise on the muscular system
As mentioned in the previous section, through fixing micro-tears in the muscle fibres you build muscle, this is termed hypertrophy. This then leads to more strength in those muscles as they have more fibres to pull at bones creating movement. To do this though you need strong tendons (fibrous tissue connecting muscle to bone) as that is what is used to pull the bone by the muscle. These tendons increase in size the same why the muscle does, by tearing through certain exercise (such as heavy weight lifting) and then being repaired to a higher standard. By consuming high levels of protein (often found in meat and nuts) your muscles can be repaired quicker and to a higher standard as it is the protein that is used in fixing the tears.
Muscles increase the amount of oxygen that they can store and use through training. To do this you need an increase in the amount of mitrochondria inside the muscle, this would allow for more energy to be produced as it is inside the mitrochondria that the reactions take place. Another change inside the muscle is an increase in ATP stores; this would help your performance as you could then extend the length of time you use the ATP/PC system to get a high level of energy. Your stores of enzymes used in the reaction to create energy will also rise through long-term exercise which will allow your body to have more reactions at one time creating more energy for longer. Myoglobin stores will also rise facilitating the need for more oxygen as the more myoglobin you have the more oxygen your muscles can store. This would all be pointless though if you didn’t not have enough fuel to use, that’s why your muscles also grow to incorporate more glycogen and fat to be used in the different energy systems for more output.
Long-term effects of exercise on the skeletal system
It is not just your muscles that grow with exercise though; your bones also
grow and strengthen with extended amounts of exercise. One way they change is by increasing the calcium stores, this then increases the pressure you can put on them. The way to increase the calcium stores best is to do exercise that places your bones under stress are strength training and weight-bearing activities that work against gravity such as basketball, tennis, jogging or dancing.
So that it is not just your bones taking the impact, your hyaline cartilage (most common type of cartilage found in the body, usually on the surface of bones inside joints) is used to absorb stress and is slightly flexible to allow this. Through training, this can grow in thickness and therefore offer more of a service when taking impact.
Ligaments (fibrous tissue that connects bone to bone) increase their pliability to allow for more weight and stress on them. This is vital as if your ligaments are not strong enough to take that stress then they will tear or snap causing lots of pain and will need lots of rest to recover.
To help with this extra movement and stress being put on your skeletal system, your body creates more synovial fluid. This is a substance that lubricates joints so that movement is smooth and controlled; this is aided by the fact that your body also lowers the viscosity (how thick it is) of this fluid so that your joints can slide and move with little resistance.
Short-term effects of exercise on the energy systems
This system is used when immediate energy is required, it works by resynthesizing the ATP through splitting PC and using the energy and Pi to turn ADP back into ATP. This process uses up the stores of PC in the retrospective muscle, of which there is a small amount, meaning that it can only be used for short intense bursts of exercise (10 seconds).
Lactic Acid System/Anaerobic Glycolysis:
This energy system is used to sustain higher intensity exercises over a longer period of time compared to the ATP/PC system (60-90 seconds) and is started by a lack of PC in muscles. In this system the breakdown of glycogen occurs however because it is an anaerobic system (doesn’t use oxygen) it cannot break it down fully therefore it ends up as lactic acid, this then limits the duration and intensity of the exercise as if the lactic acid is not removed by the circulatory system it will build up and cause cramps and pain.
Aerobic Energy System:
This system is used for long duration and low to medium intensity exercise (depending on your physical fitness and how far your body has adapted to exercise). Glycogen and fatty acids are broken down in order to produce high amounts of ATP and the only waste products are water and carbon dioxide which do not hinder your muscles in exercise. This system creates 38 units of ATP for every 1 unit of glycogen.
Have you mentioned the yield of ATP somewhere?
Long-term effects of exercise on the energy systems
One effect of long-term exercise is an increase in the size of mitrochondria and an increase in the amount of enzymes used through the energy systems. These adaptations combined mean that the production of ATP is far more efficient and can be sustained for a lot longer time.
Another adaptation is that your body uses more fats as an energy source and not just glycogen; this means that your body can then perform exercise for longer periods of time as more energy is being created and another bonus is that the body would be using more fats so that they cannot be stored as adipose tissue.