Which of the following is an additional benefit of aerobic training?

Aerobic training is known for its variety of health benefits, and one of the notable advantages is its positive impact on the immune system. Engaging in regular aerobic exercise can enhance the body’s ability to fight off infections and diseases. This improvement in immune function is believed to be due to various factors, such as improved circulation, which allows immune cells to travel more efficiently throughout the body, and the reduction of stress hormones that can negatively affect immune response.

In contrast, decreased muscle mass, increased risk of injuries, and reduced flexibility are generally not benefits associated with aerobic training. While excessive aerobic exercise without strength training can lead to muscle loss, a balanced training program includes both aerobic and resistance training to maintain muscle mass. Similarly, while it's possible for any type of exercise to lead to injuries if not performed correctly, a well-structured aerobic regimen typically focuses on safe and effective forms of movement that reduce the risk. Lastly, flexibility is typically improved through specific stretching and flexibility exercises rather than purely aerobic activity. Thus, the enhancement of the immune system is a validated and recognized benefit of consistent aerobic training.