Final answer:
The principles related to improving fitness encompass the intensity, duration, and frequency of exercise, which jointly improve muscular strength, endurance, and cardiovascular health.
Step-by-step explanation:
Principles related to improving fitness include how hard you exercise (intensity), how long you exercise (duration), and how often you exercise (frequency). These elements work together to enhance different aspects of fitness, such as muscular strength, muscular endurance, and cardiovascular health. To see the most effective improvements in fitness, a balanced approach that increases the intensity, increases the frequency, and alters the target of your workouts is typically recommended. Aerobic exercises like cycling, walking, and running are crucial for building endurance and heart health, whereas anaerobic exercises like weightlifting or sprinting primarily increase muscle strength. Finally, flexibility exercises such as stretching are essential for range of motion and injury prevention.