Heart rates and how/why they change based on a person’s activity level

As we switch from rest to activity, demand for oxygen in our body increases. We burn more energy and more oxygen is needed to perform the task. Also we produce more carbon dioxide that has to be removed from our system. As a result our heart rate will go up,resulting in our blood flowing faster through our system thus providing coverage for extra oxygen and removal of increased amounts carbon dioxide from muscle cells. 
When we go back to rest heart rate will go down back to so called basal heart rate, which is a heart rate of a human while being rested and awake. That value for a healthy person is usually between 60-80 beats per minute.

As we switch from rest to activity, demand for oxygen in our body increases. We burn more energy and more oxygen is needed to perform the task. Also we produce more carbon dioxide that has to be removed from our system. As a result our heart rate will go up,resulting in our blood flowing faster through our system thus providing coverage for extra oxygen and removal of increased amounts carbon dioxide from muscle cells. 

Because it is under the health section, i would say chemo but idk much. i'm pretty sure it's either a machine or a pill. sorry if i am wrong