Which of the following best describes the purpose of interval training?

Interval training is a technique that primarily focuses on improving performance by alternating between periods of high-intensity effort and lower-intensity recovery or rest. This method is effective for enhancing cardiovascular fitness and overall athletic performance as it pushes the body to adapt to varying levels of exertion.

In contrast, the other options focus on specific aspects of fitness that are not the main goal of interval training. Building strength through heavy lifting pertains to resistance training rather than the alternating intensity seen in interval workouts. Enhancing flexibility and mobility emphasizes stretching and range of motion, which is different from the intensity changes involved in interval training. Lastly, while interval training can develop aerobic endurance, its purpose is broader and includes performance improvements across various fitness areas, making it more versatile than the singular goal of developing aerobic endurance only.