The answer is vigorous because your body needs the oxygen to continue to move your muscles during exercise. talking while in vigorous movement inhibits your oxygen intake which is why physiologicly, u can only say short words or sentences during exercise.
During exercise, it is common breath and heart rate increase because the body requires more oxygen for the muscles and the whole body. Additionally, the higher the effort is the more the heart rate changes. In the case of running or jogging, this physical activity requires considerable effort and due to this, it leads to an important increase in the heart rate or a vigorous heart rate. Indeed during this activity, the heart rate can go as high as 200 bpm (beats per minute) but during rest heart rate is between 60-100 bpm. Thus, heart rate while Stuart and his brother run can be described as vigorous.
