Which of these exercises places the highest demands on cardiorespiratory endurance?

Swimming places the highest demands on cardiorespiratory endurance compared to the other exercises listed. This is primarily because swimming requires continuous, rhythmic movement that engages multiple large muscle groups while simultaneously challenging the cardiovascular system to deliver oxygen to the muscles and remove carbon dioxide.

As a full-body workout, swimming involves sustained physical exertion that typically lasts for longer periods without rest, heavily taxing the heart and lungs. It promotes not only muscular strength but also aerobic capacity, significantly enhancing overall stamina and endurance.

In contrast, gymnastics, baseball, and volleyball tend to consist of intermittent bursts of activity rather than steady, prolonged exertion. These sports involve periods of intense effort followed by rest, which do not place as continuous a demand on the cardiorespiratory system as swimming does. Thus, swimming stands out as the exercise that most effectively develops cardiorespiratory endurance.