The number of sports representatives may be **3**. This conclusion is mainly based on that doing exercise can be understood as doing exercise, and the process of doing exercise can be realized by shouting slogans 1, 2, 1, and the continuous pronunciation of 1, 2, 1 is similar to doing exercise. Therefore, engaging in sports can be understood as shouting slogans 1, 2, 1, 1, 2, 1 and the sum is equal to 3, so it is concluded that the number of representatives engaged in sports is 3.