Effects of Exercise on Body Systems

This lesson covers the short-term and long-term effects of exercise on the body systems as required by the OCR GCSE PE specification (J587). You need to understand how the cardiovascular and respiratory systems respond to exercise in the short term (during and immediately after exercise) and the long term (as a result of regular training over weeks and months).

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Short-Term Effects of Exercise

Short-term effects are the immediate changes that occur in the body during exercise and in the period shortly after. These changes are temporary and return to normal during recovery.

Short-Term Effects on the Cardiovascular System

Effect	Explanation
Heart rate increases	The heart beats faster to pump more blood to working muscles
Stroke volume increases	Each beat pumps a greater volume of blood
Cardiac output increases	Q = SV x HR; both increase, so cardiac output rises significantly
Blood redistribution occurs	Blood is redirected from non-essential organs to working muscles via vasodilation and vasoconstriction
Increased oxygen delivery to muscles	More oxygenated blood reaches the working muscles per minute
Increased muscle temperature	Increased blood flow warms the muscles, improving enzyme efficiency and muscle elasticity
Lactic acid production (during anaerobic exercise)	If exercise is intense enough, lactic acid builds up in the muscles

Short-Term Effects on the Respiratory System

Effect	Explanation
Breathing rate increases	More breaths per minute to increase airflow to the lungs
Tidal volume increases	Deeper breaths move more air per breath
Minute ventilation increases	VE = TV x BR; both increase, so total airflow per minute rises
Increased oxygen delivery to alveoli	More O₂ reaches the alveoli for gaseous exchange
Increased CO₂ removal	More CO₂ is exhaled from the alveoli
Bronchodilation	Bronchioles widen to allow more air to reach the alveoli

graph TD
    A["Exercise Begins"] --> B["Cardiovascular<br>Responses"]
    A --> C["Respiratory<br>Responses"]
    B --> D["↑ Heart rate"]
    B --> E["↑ Stroke volume"]
    B --> F["↑ Cardiac output"]
    B --> G["Blood redistribution"]
    B --> H["↑ Muscle temperature"]
    C --> I["↑ Breathing rate"]
    C --> J["↑ Tidal volume"]
    C --> K["↑ Minute ventilation"]

    style A fill:#4a90d9,color:#fff
    style B fill:#e67e22,color:#fff
    style C fill:#27ae60,color:#fff

Exam Tip: When describing short-term effects, always explain the REASON for each change. For example, do not just write "heart rate increases" — write "heart rate increases to pump more oxygenated blood to the working muscles to meet the increased demand for oxygen."

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Long-Term Effects of Exercise (Training Adaptations)

Long-term effects are the permanent or semi-permanent changes that occur in the body as a result of regular training over weeks, months, and years. These are also called training adaptations.

Long-Term Effects on the Cardiovascular System

Effect	Explanation
Cardiac hypertrophy	The heart muscle (especially the left ventricle) grows larger and stronger
Increased resting stroke volume	A larger, stronger heart pumps more blood per beat at rest
Lower resting heart rate (bradycardia)	Because SV is higher, the heart needs fewer beats to pump the same cardiac output at rest
Faster recovery rate	The heart rate returns to resting levels more quickly after exercise
Increased capillarisation	New capillaries grow around the muscles, improving oxygen delivery and waste removal
Increased red blood cell count	More red blood cells means more oxygen can be transported in the blood
Lower resting blood pressure	A more efficient cardiovascular system reduces the strain on blood vessel walls

Long-Term Effects on the Respiratory System