I think it's the manufacturer <span />
20-40 mins depending on the person....but would not try it but...if you have to...slightly bend your knees to help your blood circulate..that would prevent you from passing out..
Answer:
Subtract your heart's resting rate from your maximum rate. For example, if you are 40 years old, subtract that number from 220; your maximum rate is 180. Next, subtract your resting rate or 80 in this example. Your heart-rate reserve is 100 beats per minute.
<span>The lungs are the respiratory structure that controls breathing. They make up a substantial part of the respiratory system, along with the trachea, the ribs, the intercostal muscles and the diaphragm. Each lung contains small tubes called bronchioles which end in air sacs called alveoli.</span>
