GLOSSARY

The chambers of the heart are its four internal spaces: two atria above that receive blood and two ventricles below that pump blood.

The Four Chambers

• Right atrium: receives deoxygenated blood from the body via the venae cavae and coronary sinus.
• Right ventricle: pumps deoxygenated blood to the lungs via the pulmonary artery.
• Left atrium: receives oxygenated blood from the lungs via the four pulmonary veins.
• Left ventricle: pumps oxygenated blood to the whole body via the aorta; the thickest chamber.

Characteristics

• Atria: thin walls and low pressure; they act mainly as reservoirs and complete ventricular filling, with atrial contraction providing about 20 percent of ventricular filling.
• Ventricles: thick, powerful walls; left ventricular pressure is about 120 mmHg and right ventricular pressure about 25 mmHg.
• Volume: each ventricle pumps about 70 millilitres per beat at rest; the output of the two ventricles must be equal over time.

Relevance to Sport

• Athlete’s heart: endurance training increases mainly ventricular cavity volume and strength training mainly wall thickness, although this distinction is not absolute in reality.
• Atrial fibrillation: very long-standing endurance athletes are at slightly higher risk of this arrhythmia in later life.