Looking at the graph closely we can see that the heart rate
increases from 0 to 6 min then became steady from 6 to 25 min then finally
decreases from 25 to 30 min. Therefore the correct answer is:
“The heart rate increases for 6
minutes, remains constant for 19 minutes, and then gradually decreases for 5
minutes.”
In real life cardiac exercises, we can
interpret that the period from 0 to 6 min is the period where the person is
still warming up thus leading to an increase in heart rate. At 6 min, the
person is fully warmed up hence reaching a stable heart rate. Then at 25 min,
the person starts cooling down which means that the exercise is ending soon.
