Intense training can lead to elevated levels of cortisol, the body's stress hormone. While cortisol plays a role in metabolism and energy regulation, prolonged high levels can lead to negative consequences, including impaired recovery, increased fatigue, and potential muscle breakdown. Balancing intense workouts with rest days and incorporating stress management techniques, such as mindfulness or adequate sleep, is essential. Monitoring training intensity can help mitigate excessive cortisol responses, ultimately promoting better performance and health outcomes.