Component 1: Fitness and Body Systems Study Guide

The cardio-respiratory system, composed of the cardiovascular and respiratory systems, is crucial for supporting physical activity by supplying oxygen to working muscles and removing metabolic waste products like carbon dioxide. The cardiovascular system (heart, blood vessels, and blood) circulates blood throughout the body, delivering oxygen and nutrients and transporting waste. The respiratory system (lungs, airways, and breathing muscles) facilitates gas exchange, taking in atmospheric oxygen and expelling carbon dioxide from the body. During exercise, these systems adapt significantly: heart rate, stroke volume, and breathing rate increase to enhance oxygen delivery and carbon dioxide removal, directly influencing athletic performance, overall health, and training adaptations.

The body primarily uses two energy systems during physical activity: aerobic and anaerobic. Aerobic exercise, meaning 'with oxygen,' relies on oxygen to break down glucose and fat for sustained energy production. This system is efficient for longer-duration activities at moderate intensity, such as long-distance running or swimming. Anaerobic exercise, meaning 'without oxygen,' generates energy rapidly for short bursts of high-intensity activity, like sprinting or weightlifting, by breaking down glucose without oxygen. However, this produces lactic acid, leading to muscle fatigue. Understanding when each system is predominant helps athletes tailor training for specific performance goals, optimise recovery, and promote overall health.