Effects of exercises on cardiovascular system

The cardiovascular system undergoes various changes if exercises are performed. During exercise, the cardio vascular system begins to meet the increased demands of the body in many ways. The cardio vascular system rushes oxygen to the working muscles, returns the blood to the lungs to be re-oxygenated and delivers fuel [ nutrients and oxygen ] to the active tissues of the body. In fact, the effects of exercise can be studied in the following ways:

1. Immediate effects of exercises
2. Long term effects of exercises

Immediate effects of exercises

When we perform exercises, there are some immediate effects on our cardio vascular system. The immediate effects are stated below:

• Increase in heart rate - Generally the resting heart rate of an adult remains at 72 beats per minute. The elite endurance athletes usually have 28 to 40 beats per minute. Even before the beginning of exercise the heart rate increases in anticipation. It is known as anticipatory response. When an individual starts exercise his heart rate increases as per the intensity and duration of the exercise.

• Increase in stroke volume - Stroke volume is the amount of blood ejected per beat from the left ventricle. It is measured in ml/beat. Stroke volume increase proportionally with exercise intensity. In untrained individuals the stroke volume at rest remains at 50 to 70 ml/beat. It increases up to 110 to 130 ml/beat during intense exercise. The stroke volume of experienced athletes at rest remains at 90 to 110 ml/beat. It increases up 150 to 220 ml/beat during intensive exercise. 

• Increase in cardiac output - Cardiac output is the amount of blood pumped by the heart in one minute. It is measured in litre/minute. Cardiac output is a product of stroke volume and heart rate. If either heart rate or stroke volume increases or both, the cardiac output also increases. The cardiac output increases proportionally with the intensity of exercise. At rest the cardiac output is about 5 litre/minute but during intense exercise it can increase up to 20 to 40 litre/minute.

• Increase in blood flow - The cardio vascular system can redistribute more blood to those tissues which have immediate demand and less blood to those tissues which have less demand for oxygen. Generally, at rest 15 to 20% circulating blood supplies to skeletal muscles. It increases to 80 to 85% of cardiac output during intensive exercise. Blood is moved away from the main organs such as liver, intestines and kidneys. In fact, it is redirected to the skin to enhance heat loss.

MUST SEE: effects of exercise on muscles!

Long term effects of exercises

After performing exercises for long term, certain adaptations take place in our cardio vascular system. These are called long term effects of exercise. The various long term effects of exercises are stated below:

• Increase in the size of heart - When we perform regular exercise the muscles of the heart increase in size and strength. In fact, the left ventricle adapts to the greatest extent. The heart walls grow stronger and thicker. The recent studies show that the myocardial wall thickness also increases. 
  

• Decrease in resting heart rate - Regular exercise decreases the resting heart rate. If a 10 week training programme is given to an individual whose initial resting heart rate is 72beats per minute, after this duration his resting heart rate may reduce upto 10 beats per minute. After regular exercise the heart finally becomes more efficient. It does not require to beat as quickly to supply the body with blood while at rest. It has been noted that highly conditioned athletes can have their resting heart rates in the 30s.

• Stroke volume increases at rest - Regular exercise helps in increasing the stroke volume at rest. The stroke volume at rest remains up to 50-70 ml/beat in untrained individuals, 70-90 ml/beat in trained individuals and 90-110 ml/beat in the elite endurance athletes. 

• Increase in blood volume - Th regular exercises increase the blood volume. In fact, there is an increase in plasma volume which enhance the blood volume. In addition, the body produces a greater number of red blood cells in order to keep the muscles supplied with oxygen during heavy exercises.

• Reduced risk of heart diseases - Regular exercise gradually reduces stress related hormones from circulating in the blood. This increases the blood vessel path, which in turn lowers the risk for the build up of plaque that can lead to coronary heart diseases. Hence, exercises reduce the risk of heart diseases.