Food is eaten and  converted to fuel/waste  fuel is transported in the blood and can be used direct from the blood (glucose, free fatty acids) or stored for future use (glycogen in muscles,triglycerides in fat cells)  These fuels provide the energy needed for the re- synthesis of ATP in the aerobic energy system (glycogen is also used in anaerobic glycolysis ie:the Lactic Acid System)

 is stored in muscles  is made up of one adenosine molecule and three phosphate molecules  the splitting of one of the phosphate molecules produces the energy required for muscular contraction and leaves behind ADP and one free phosphate

 are there to re-connect the free phosphate OR create a new phosphate to replace the one used. So the energy systems re- synthesise ATP  the blood borne and stored fuels are used to provide the energy for that re-synthesis (glucose, free-fatty acids glycogen, triglycerides, creatine-phosphate, adipose fat)

Circulatory/Respiratory systems Volume of left ventricle increases after aerobic training Hypertrophy of the left ventricle occurs after anaerobic training Capillary network of the lungs increases Haemoglobin count (in blood) increases Elasticity of lungs improves Lung volumes increase

Aerobic training effects at the working muscles Capillarisation to muscle increases Mitochondria increase in size and number Myoglobin concentration increases Triglyceride stores increase Glycogen stores increase Oxidative enzymes increase

Anaerobic training effects at the working muscles Hypertrophy of the muscle occurs (mainly reflecting an increase in the size of the fast-twitch fibres) Glycogen stores increase Glycolytic enzymes increase in number Capillarisation increases Phospho-creatine stores increase Muscle stores of adenosine triphosphate increase Production of lactic acid at sub-maximal workloads falls Speed and force of contraction increases Connective tissue strength (tendons and ligaments) increases

Increased lung volume means  more air in lungs therefore more O 2 available to the blood Increased haemoglobin in blood means  greater potential for O 2 absorption into the blood Broadened network of capillaries on lungs means  bigger surface area for direct contact between blood and the O 2 in the lungs

Cardiac hypertrophy means  thicker/stronger heart walls & larger left ventricular chamber  a greater stroke volume  a greater volume of blood can be pumped with the same number of beats  at rest, the heart will beat fewer times Increased stroke volume means  maximum cardiac output (Q) is increased  potential VO 2 maximum increase

Increased myoglobin concentration in the muscles means  greater potential for O 2 extraction from blood, therefore increased a-VO 2 difference Increased size & number of mitochondria in the muscles means  greater potential for aerobic re-synthesis of ATP as there are more aerobic energy production sites and each can produce more Increased glycogen storage in muscles means  more immediately available fuel for ATP re-synthesis (both aerobic & anaerobic)

Increased concentration of glycolytic enzymes means  greater potential for immediate glycolysis (Lactic Acid System)  therefore less demand on PC stores (ATP-PC system)  more efficient activation and ongoing energy production by the Aerobic system

 When we exercise, the most efficient way of re- synthesising ATP is through our aerobic system, where O 2 is used and the muscles during the re-synthesis  The O 2 needed comes from the blood  The changes mentioned provide for …greater O 2 absorption into the blood …and therefore, increased volume of O 2 delivery to muscles …and also, increased extraction of O 2 by the muscles

…and that makes for greater aerobic fitness as shown by a higher VO 2 max

 being able to exercise at the same level of performance for longer periods before fatiguing  being able to work at a higher level of performance for at least the same period of time  being able to work at higher level of performance without crossing the lactate threshold  reducing the need to use the lactic acid system  more efficient energy production at higher levels of performance and therefore less stress on the body  greater potential for using fat as an aerobic fuel source instead of glycogen (glycogen sparing), so also greater potential for extended surges of effort (eg: end of race or late in the match) which rely predominantly on the lactic acid system  being able to recover more efficiently (quicker) in terms of systems returning to resting levels (breathing, HR, fuel storage, ATP levels, blood lactate)