Too much and too little exercise

Biology Unit 5

The effects of too much and too little exercise

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Biology Unit 5
Revision Notes
Topic 7: Run for your life
18. Analyse and interpret data on possible
disadvantages of exercising too much (wear and tear
on joints, suppression of the immune system) and
exercising too little (increased risk of obesity,
coronary heart disease (CHD) and diabetes),
recognising correlation and causal relationships.
Correlation and Causation
Correlation doesn't necessarily mean a connection. If there appears to be a strong correlation
between two factors, a causal link/relationship is more likely if you can provide a biological
explanation for why one factor will affect the other, especially if there aren't many other likely
factors or explanations available.
E.g. there is a positive correlation between the number of shark attacks and the number of ice
creams sold on a beach.
There is no biological explanation for this correlation so there is no direct causal relationship.
In contrast, there is a causal relationship between the number of cigarettes smoked and the number
of deaths due to lung cancer, because there is a strong correlation and a biological explanation about
why smoking could cause lung cancer.
Too little exercise ­ the risks
Effects of a lack of exercise over a prolonged period of time:
Reduced physical endurance, lung capacity, stroke volume and maximum heart rate
Increased resting heart rate, blood pressure and stored body fat
Increased risk of coronary heart disease (CHD), type II diabetes, some cancers, weight gain
and obesity
Impaired immune response due to lack of natural killer cells
Increased levels of LDL (bad cholesterol) and reduced levels of HDL (good cholesterol)
Reduced bone density so risk of osteoporosis increases
Text Book: p. 168 -171

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Biology Unit 5
Revision Notes
Too much exercise ­ the risks
Effects of exercising too much:
There is some evidence of a correlation between intense exercise and the risk of infections
such as colds and sore throats
Suppression of the immune system after extreme exertion
Viruses spread easily from non-athletes to athletes
Travel such as airplanes can increase risk of exposure to pathogens
Intense exercise lowers the numbers and activity of T killer cells and phagocytes, B cells
and also T helper cells
Increases the…read more


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