Molly is jogging on the treadmill. After 20 minutes, her heart rate has not increased, she is able to talk, and she is not sweating. If Molly wants to improve her fitness level, what should she do?
Molly could increase her heart rate by turning around and jogging backwards, by jogging on her hands instead of her feet, or by continuing to jog normally but increasing the speed of the treadmill.
