CARDIO CONDTIONING
WE ALL DO 'CARDIO', BUT WHY?
Your heart is a ‘cardiac’ muscle at the centre of your circulatory system. The cardiovascular system consists of a network of blood vessels that carry blood and nutrients to (via the arteries) and from (via the veins) all areas of your body. Your heart is controlled by internal receptors that produce electrical signals to contract and relax the heart. When the walls contract, blood is pumped into your circulatory system.
THE FACTS
At rest, the cardiac output (total volume of blood pumped out of the heart) is about 5 litres per minute. When the heart is pumping at full force, the cardiac output reaches around 20-25 litres per minute.
During exercise, by-products from muscles (lactic acid, hydrogen ions, carbon dioxide) in the blood stimulate the respiratory centres in the brainstem to signal the respiratory muscles to become more active. The primary respiratory muscles are the diaphragm and external intercostals (the thin muscles between each individual rib). All muscles that are attached to the ribcage have the potential to cause a breathing action, including the chest muscles, abdominals and upper neck.
Higher blood pressures during exercise increase the blood flow to the lungs for oxygen exchange to take
