Short-Term Effects of Exercise

When you begin exercising, your body responds immediately to meet the increased demand for energy. These responses are called short-term effects (or acute responses) because they happen during and shortly after exercise, and they reverse once you stop and rest. Understanding these effects is essential for the Edexcel GCSE PE specification (1PE0 — Topic 1: Applied Anatomy and Physiology). You must be able to describe each effect and explain why it happens.

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What Are Short-Term Effects?

Short-term effects of exercise are temporary physiological changes that occur in response to physical activity. They begin as soon as you start exercising and return to normal once you stop and recover. They are the body's way of ensuring that the working muscles receive enough oxygen and energy to sustain the activity.

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Key Short-Term Effects

1. Increased Heart Rate (HR)

During exercise, the heart beats faster to pump more blood — and therefore more oxygen and glucose — to the working muscles. At rest, the heart rate of an average adult is approximately 72 bpm. During vigorous exercise it can exceed 180 bpm or more.

Why does it increase?

• Working muscles demand more oxygen and glucose for energy production.
• More carbon dioxide needs to be removed as a waste product.
• The brain detects the increased demand and sends nerve impulses to the heart via the sympathetic nervous system, increasing the rate.
• Hormones such as adrenaline are released, which also increase heart rate.

Condition	Approximate Heart Rate
Rest (untrained adult)	60–80 bpm
Light exercise (walking)	90–110 bpm
Moderate exercise (jogging)	120–160 bpm
Vigorous exercise (sprinting)	170–200+ bpm

2. Increased Breathing Rate and Depth

Both the rate (number of breaths per minute) and depth (tidal volume — the amount of air per breath) increase during exercise.

Why?

• The body needs to take in more oxygen from the atmosphere to supply the working muscles.
• The body needs to expel more carbon dioxide, a waste product of energy production.
• Receptors called chemoreceptors in the brain and blood vessels detect rising CO₂ levels and trigger faster, deeper breathing.

Condition	Breathing Rate (breaths/min)	Tidal Volume (litres)
Rest	12–20	~0.5
Moderate exercise	30–40	~1.5–2.0
Vigorous exercise	40–60+	~2.5–3.0+

3. Increased Body Temperature

Muscles working harder produce more heat as a by-product of energy production. Core body temperature rises from about 37 °C at rest and can exceed 39 °C during intense exercise.

4. Sweating

As body temperature rises, the body activates its cooling mechanism: sweating. Sweat is produced by sweat glands in the skin and is released onto the surface. When sweat evaporates, it takes heat energy with it, cooling the body down. This process is called evaporative cooling.

5. Vasodilation and Skin Redness

Vasodilation is the widening (dilation) of blood vessels near the skin surface. This allows more blood to flow close to the skin, where heat can be lost to the environment by radiation. This is why the skin often appears red or flushed during exercise.

Exam Tip: Make sure you can distinguish between vasodilation (blood vessels widen to lose heat through the skin) and vasoconstriction (blood vessels narrow to conserve heat or redirect blood flow). Edexcel may test both.

6. Muscle Fatigue

During prolonged or high-intensity exercise, muscles begin to fatigue — they become less efficient and the performer feels tired and may experience a burning sensation. Fatigue during anaerobic exercise is largely caused by the build-up of lactic acid. During aerobic exercise, fatigue may result from the depletion of glycogen stores or dehydration.

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How Short-Term Effects Are Linked