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Science

Respiration

Effect of exercise on breathing

During exercise, the muscle cells respire more than they do at rest. This means:

  • Oxygen and glucose must be delivered to them more quickly
  • Waste carbon dioxide must be removed more quickly

This is achieved by increasing the breathing rate and heart rate. The increase in heart rate can be detected by measuring the pulse rate. The stroke volume also increases – this is the volume of blood pumped each beat. The total cardiac output can be calculated using the equation:

Cardiac output = stroke volume x heart rate

During hard exercise, the oxygen supply may not be enough for the needs of the muscle cells. When this happens, anaerobic respiration takes place, as well as aerobic respiration.

Fitness versus health

Fit people are able to carry out physical activities more effectively than unfit people. Their pulse rate is likely to return to normal more quickly after exercise.

But being fit is not the same as being healthy. Healthy people are free from disease and infection: they may or may not be fit as well. It is possible to be fit but unhealthy, or healthy but unfit.

Back to Organisms and energy index

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