In a marathon... By sAffy, Jess and Freya

What is marathon running?

-We are going to be looking at the long and short term effects of marathon running. An athlete will be using mostly aerobic respiration (98%) while running but can small amounts of anaerobic respiration can take place (2%).

There are many short term effects on the body during a marathon. We can split these into 4 categories: cardiovascular, respiratory, muscular and skeletal.

Short term respiratory effects

-Almost immediately after starting your marathon will you begin to breath heavier, not only this but the tidal volume will also increase to take in more oxygen. This oxygen will be taken to the muscles where it will be transferred to energy.

-To increase the speed of air flow intercostal muscles and the diaphragm contract with more force. This way oxygen to can flow to the capillaries quickly so that more gas exchange can take place.

-A larger intake of oxygen means more waste products are produced. Carbon dioxide being one of these products means that larger amounts of it is breathed out.

Long term effects on the respiratory system

When you breath your diaphragm intercostal muscles contract to bring the chest up- they are a vital part of breathing. The long-term effect of exercise is to build the endurance of these respiratory muscles so that deeper and more efficient breaths can be taken.

When you exercise your muscles tear and repair bigger and stronger than before. To supply these bigger muscles that have a larger demand for oxygen more capillaries are created and with production of more capillaries comes more alveoli as a capillary alone wouldn't be useful for gas exchange. The increase in capillaries and alveoli means that gas exchange can take place on a greater scale.

Long term effects on the cardiovascular system

If you are unfit, your veins and arteries become blocked by a buildup of cholesterol or fat, so it’s harder for your heart to pump your blood to where it needs to be. Regular exercise can prevent potential blockages (plaque) and makes it easier for your blood to flow. This will benefit a marathon runner as more oxygen can easily flow to the working muscles, providing energy quickly ans efficiently.

Your resting heart rate will be lower as aerobic exercise strengthens your heart and trains it to pump more blood per contraction, decreasing the number of beats as more blood is pumped (per beat). this benefits a marathon runner as it is an indication of how fit they are as they require less heart beats to get more oxygen around their body.

Your recovery heart rate quickens if you're physically fitter as this means that your body can handle the stress you put it through better . The fitter your heart is, the quicker it can meet the 'demands' and recover to its normal pace as intensity decreases. This benefits a marathon runner as they can recover and restart training quicker, strengthening their cardiovascular system.

Stroke volume increases if you're fitter, so more blood is pumped per beat. this transports more oxygen and glucose to the muscles, and carbon dioxide away from the muscles. This benefits a marathon runner as they can exercise for longer and won't fatigue as quickly as more oxygen and energy is being delivered to the muscles.

When your stroke volume increases, so does your cardiac output as the heart is able to pump out more blood in one beat. This is beneficial to marathon runners because if their maximum cardiac output is increasing, it means heart rate and stroke volume are too, which provides more blood in less beats, providing more energy and oxygen to working muscles.

Hypertrophy is when the heart increases in size and strength over a period of time in order to deal with more work and high pressure. This is good for marathon runners as more blood is pumped around the body, resulting in more oxygen for energy.

If your blood pressure reading is normal it won't change much. However, if it is unhealthily high, long term exercise can help to bring this down, avoiding strokes, heart attacks and can remove cholesterol from blocking your arteries which helps a marathon runner as it reduces risks of heart attacks and strokes, making you generally fitter.

When you exercise your capillary density will increase, also known as capillarisation. this provides working muscles with oxygen-rich blood and remove carbon dioxide. this aids a marathon runner as carbon dioxide and lactic acid can be removed quicker, meaning the athlete will fatigue at a slower rate.

Short term effects on the cardiovascular system

Increased heart rate- when the amount of time that your heart beats per minute (bpm) increases.

Heart contracts with more force- your heart will begin to beat more forcefully to meet the demand to deliver oxygen to working muscles.

Vasoconstriction and vasodilation occurs- your veins change in size to regulate your body temperature and to redirect blood to places where it is more important (working muscles) rather than unnecessary places such as your digestive system.

Release of adrenaline- when your brain sends signals for your body to release the hormone adrenaline which speeds up your heart rate.

Systolic blood pressure increases- the pressure of blood in your heart when it beats will increase.

Stroke volume increases- the amount of blood pumped by your left ventricle per beat will increase.

Blood becomes more acidic (CO2+lactic acid)- during aerobic metabolism your body releases carbon dioxide int your blood. The combination of carbon dioxide and hydrogen creates a reaction that makes your blood acidic.

Cardiac output increases- working muscles send more amounts of blood back to your lungs for oxygen, therefore cardiac output increases due to increased stroke volume and heart rate.

How these effects are linked with Marathon runners:

The athletes heart rate will begin to increase from the moment that they start running. Heart rate stays relatively constant for the majority of the race however if the athlete has a faster start or has a sprint finish, these figures could fluctuates.

As the athletes heart rate increases, their heart contracts with more force. This is because the athletes body needs to pump out more blood to keep up with the working muscles demand for nutrients and oxygen as they are working for a long time in the marathon and need to remove wast products. The heart contracts with more force to pump out more blood, quicker.

The athletes blood vessels will also begin to go through processes called vasoconstriction and vasodilation. This is where the veins in the athletes body will redirect the blood to places that it is most needed during the race. The veins that go to the places such as the digestive system will vasoconstrict to reduce the amount of blood flow to dormant systems in the body and vasodilate at the working muscles to increases blood flow to them to make exchanges happen more frequently and at a larger scale.

When the athlete is near the end of the race, their body will release adrenaline. The brain releases a hormone called adrenaline which speeds up the heart and results in blood being pumped out at a faster rate.

The systolic blood pressure of the athletes heart will increase during the race as it will be pumping out more blood than at rest as the body is constantly working during a marathon. The systolic blood pressure may be higher at times where the athlete is working at a higher intensity.

The athletes stroke volume will increases as a short term effect of running a marathon. This means that their left ventricle will pump out much more blood. This is because it needs to keep up with the constant demand for more blood,oxygen and nutrients to complete aerobic respiration.

The athletes blood can become more acidic during the marathon race. This will happen when the athlete is working at a high intensity (possibly if they choose to finish with a sprint). When the body cannot keep up with the demand of oxygen to aid gaseous exchange/ aerobic respiration, the body releases carbon dioxide into the blood. The combination of carbon dioxide and hydrogen causes a chemical reaction to take place which causes your blood to become slightly more acidic.

The final way in which the athletes cardiovascular system will change as a short term effect of running a marathon is that their cardiac output will increase. Cardiac output is the amount of blood pumped out of the heart per minute. This will increase due to the fact that there is a larger demand for blood in the body for processes such as gaseous exchange and aerobic respiration. The muscles also need to be supplied with energy which is converted into by glucose which is made when the body breaks down carbohydrates/fat using amylase or lipase which is then transported into the bloodstream.

Long term effects on the cardiovascular system

Short term effects on the skeletal system

In the skeletal system there is an increased production of an oil-like substance called synovial fluid. The fluid keeps joints healthy, stops cartilage from drying out and keeps it lubricated.

Long term effects on the skeletal system

Bone density increases. This means that the size and weight of the bones increases, they become strong and flexible. Exercises such as running, hiking and jumping rope will increase bone density

Ligaments and tendons will increase in flexibility and strength as a result in exercise. Large amounts of exercise will decrease the risk of them tearing.

Short term effects on the muscular system

After exercise the muscle tissue (warm muscle) is bigger than cold muscle, because of blood flow into them. It can increase by up to 25 times because muscle requires more energy and oxygen.

Muscle fatigue is the decline in ability to generate force because of intense exercise. There are two main causes of muscle fatigue. Neural fatigue, when the nerve cannot sustain a signal and metabolic fatigue, when the muscle fibre is unable to properly contract.

Muscle exhaustion is when exhaustion often occurs after you have done too much activity at one time, such as taking an extra-long hike. The athlete may feel weak and tired, or your muscles may be sore. These affects usually only last a few days.

Muscle damage is when the muscle is worked too hard to the point the muscle fibres become damaged. When a muscle fibre is damaged the body immediately starts to repair it at the cellular level. Most of the time the muscles repair by themselves (if body is functioning properly) through time.

Cramp is very painful, it can be caused from over-exercise, lack of nutrients like magnesium or bad blood circulation when muscles don’t receive enough oxygen.

Long term effects on the muscular system

Muscle size is mostly determined by persons genetics, but can be affected by exercise, and healthy food. Exercising specific muscles regularly can increase their size by up to 60%. This increase in muscle size is due to the increased diameter of individual muscle fibres.

Muscle coordination trains muscles to work more efficient and effectively by working together. For example, when the agonist contracts more rapidly the antagonist must also relax as quickly to prevent blocking the movement.

Blood supply is a result of repeating and maintaining exercise over a period of time. This increases the amount of blood vessels in the body and the extent of the capillary beds.

The effects of exercise on the muscular system would benefit by increasing size and number of mitochondria, improved perception of muscle tone and also overall improved:

Coordination, Power, Balance, Speed, Agility, Body composition, Reaction time, Muscular endurance and Flexibility

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