Effects of Exercise 11PHE - Exercise Physiology 2011

Types of effects  The effects of exercise can be separated into two categories:  Acute – short term responses  Chronic – long term responses

Acute responses to exercise  Immediate, short term effects that only last for the duration of the exercise and recovery period. Can you name some (acute) short term effects?

Chronic responses to exercise  Long term effects of exercise which occur after a sustained period of time (i.e. 6 – 12 months of training). Can you name some (chronic) long term effects?

Acute Responses to exercise  Body temperature increases – Red skin/ sweating  Heart Rate increases  Stroke volume increases  Increased Respiration rate  Blood pressure increases

Body Temperature Increases  Due to repeated muscular contractions, the body’s core temperature increases.  The body attempts to cool itself down using several methods (i.e. skin colour change, sweating) Skin colour change:  When we exercise the body attempts to cool itself by bringing the blood close to the surface of the skin.  It does this by dilating (opening) blood vessels close to the skin which gives it it’s red appearance.  This occurs mainly in the arms, chest and face. Sweating:  Is the body’s attempt to cool itself and bring itself back to a constant temperature.  It occurs from the sweat glands and we bring it to the surface through our pores.  Sweating provides moisture (made up of water, salt and other chemicals) which is evaporated from the skins surface, which gets rid of heat energy.

Heart Rate increases  Our heart rate is the number of heart beats per minute (bpm)  We can measure our heart rate manually. 2 common places are two arteries – radial (arm) or carotid (neck). These are measured by placing two fingers on the artery.  When we begin exercising the working muscles require more oxygenated blood to keep them working to sustain the exercise we are doing.  This means that the heart beats faster to ensure it is able to pump blood around the body, back through the lungs (to become oxygenated), and back through the body again.  Our heart rate increases in proportion to the level of exercise / demand placed on the heart What links could you make to the cardiovascular and respiratory systems?

Stroke Volume Increases  Stroke volume is the amount of blood the heart can pump in one beat.  Blood is pumped through the body by the left ventricle which has thicker walls due to the force that is required to get it around the body.  In exercise, the stroke volume increases because the working muscles have a high demand for oxygenated blood to remain active.  Therefore, the heart has to eject more blood per beat to sustain the body’s activity.

Increased Respiration Rate  Put simply, when we exercise we breath more often.  The heart has a high demand for oxygenated blood as it needs to pump it around the body to the working muscles. The respiratory system takes in more oxygen to also meet this demand.  The respiratory system needs to take in more air (oxygen) so that it can oxygenate the blood within the aveoli.  When the blood has been oxygenated within the aveoli, it is pumped back into the heart via the pulmonary vein.  Our respiration rate is determined by the level of exercise we are doing and how fit we are. If we have a high level of fitness, our breathing rate will slowly increase, whereas if we are unfit it will increase quickly.  If we are going for a run, our breathing rate will increase faster than if we were going for a jog or walk.

Blood Pressure Increases  Blood pressure is the measurement of force placed upon the artery/vein wall.  When we exercise, our heart is working hard at getting oxygenated blood around the body to the working muscles.  Our stroke volume increases – which is the amount of blood the heart can pump per beat.  The result of this is that we have increased levels of blood travelling through the arteries and veins despite no change in their size.

Chronic Responses to exercise  Cardiac hypertrophy – increased heart size  Decrease in resting heart rate  Decrease in body fat  Increased heat acclimatisation

Cardiac hypertrophy  The heart is a muscle and therefore its size can be increased (slightly).  This is a healthy adaptation to exercise as it increases the hearts mass and pumping ability.  The increase happens within the ventricles with some athletes increasing their left ventricle walls from 1.1cm to 1.3cm.  Cardiac hypertrophy occurs due to the hearts sustained ability to pump high levels of blood through the body, and is linked to an increased stroke volume.

Decrease in resting heart rate  After a sustained period of exercise the heart becomes more efficient at pumping blood around the body.  Cardiac hypertrophy is linked to this concept as the heart can now hold and pump more blood, which means it doesn’t have to beat as many times per minute (bpm).  This is also linked to stroke volume (chronic response), as the heart is able to pump a larger volume of blood per beat.

Decrease in body fat  When we exercise, our body burns calories through an increase of our heart rate.  To burn calories we need energy which comes from food. This is broken down into fats, carbohydrates, and proteins.  We need to make sure we are exercising between 60-85% of our maximum heart rate to see a decrease in our body fat levels.  We can estimate our maximum heart rate by using the following equation: Max heart rate = 220 – age

Increased heart acclimatisation  In reference to the acute response to exercise where the body attempts to cool itself through sweating and dilating (opening) blood vessels, increased heat acclimatisation is discussing the body’s ability to handle this efficiently after a sustained period of exercise.  The body increases it ability to work under high levels of stress through the cardiovascular responses (i.e. increased stroke volume, cardiac hypertrophy) and the respiratory responses (i.e. increased lung capacity)  Bones, muscles, ligaments and tendons adapt to be able to withstand higher levels of stress which means they take longer periods of time to heat up and require the necessary responses (sweating/red skin).