We know that
when we start exercise our hear beats starts increasing gradually
because blood flowing rate becomes higher
and it keeps increasing upto a certain limit
because for normal human beings maximum heart rate is 135 beats per minute
and it remains constant there for few minutes
and as we slow down slowly
It will start decreasing gradually and then becomes normal
we can see the graph
so,
The heart rate increases for 6 minutes, remains constant for 19 minutes, and then gradually decreases for 5 minutes..........Answer
