AS Level Sport & PE - Applied Physiology & Skills

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Antagonistic Muscle Action

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A pair of muscles working in opposition to control a joint. The **agonist** contracts to cause movement (prime mover), while the **antagonist** relaxes to allow the movement. *Example: During a bicep curl, the biceps are the agonist and the triceps are the antagonist.*

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Fibre Types: Slow vs. Fast Twitch

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**Slow Oxidative (Type I):** Fatigue-resistant, red color (high myoglobin/capillaries), suited for endurance. **Fast Glycolytic (Type IIb):** Fatigable, white color, low capillary density, suited for explosive power/speed. *Example: Marathon runners possess a higher percentage of Type I fibers.*

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Cardiac Drift

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The gradual increase in heart rate during prolonged, steady-state exercise to compensate for a decrease in Stroke Volume (SV). This decrease is often caused by plasma volume loss due to sweating and increased venous pooling.

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Vasodilation vs. Vasoconstriction

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**Vasodilation:** Widening of blood vessels (increased radius) reducing resistance and increasing blood flow to muscles and skin (thermoregulation). **Vasoconstriction:** Narrowing of blood vessels increasing resistance and redirecting blood to vital organs.

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Respiratory Adaptation: The Bohr Effect

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A physiological phenomenon where increased CO2 and decreased pH (acidity) in active muscles facilitate the release of oxygen from hemoglobin. This ensures oxygen is delivered precisely where it is needed most for aerobic respiration.