Final answer:
Cross-training is the use of several training methods to develop a specific fitness component, often incorporating vigorous and medium intensity exercises.
Step-by-step explanation:
Using several modes of training to develop a specific component of fitness is known as cross-training. This approach involves integrating diverse exercises or activities to improve a particular aspect of physical fitness. For example, cross-training for endurance might include a pattern of physical exercise that combines short periods of vigorous muscular work with longer periods of medium and varied muscular work. By incorporating different types of workouts, individuals can target specific fitness goals while reducing the risk of injury and improving overall performance.