What would be the control variable?

I am doing a graph about blood pressure. The lab was to find the blood pressure of a person while they were resting. Then find the blood pressure after 5 minutes of exercise. Then find the blood pressure again 2 minutes after that. On the graph, time is on the bottom(independent variable) and blood pressure is on the y-axis(dependent variable). What is my control variable?|||the blood pressure when the person is resting.|||The control would be the blood pressure while the person was resting because a control is a variable that has not been changed or manipulated. The exercise is the independent variable and the blood pressure after the exercise is the dependent variable. Hope that helps|||Yeah the control is the one that you don't alter. The excercise alters the blood pressure so its not controlled|||The amount of time to exercise, rest, ect. It's the one that has to be precise.